MFJ -1270C System Manual
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MFJ -1270C System Manual

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o 15.838 Class B computing device: information to user.
This equipment generates and uses radio frequency energy and if not installed
and used properly, that is, in strict accordance with the manufacturer's
instructions, may cause interference to radio and television reception. It has
been type tested and found to comply with the limits for a Class B computing
device in accordance with the specifications in subpart J of Part 15 of FCC
Rules, which are designed to provide reasonable protection against such
interference in a residential installation. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does
cause interference to radio or television reception, which can be determined by
turning the equipment off and on, the user is encouraged to try to correct the
interference by one or more of the following measure:
Reorient the receiving antenna
Relocate the computer with respect to the receiver
Move the computer away from the receiver
Plug the computer into a different outlet so that computer and receiver are
on different branch circuits.
If necessary, the user should consult the dealer or an experienced radio/television
technician for additional suggestions. The user may find the following booklet
prepared by the Federal Communications Commission helpful:
"How to Identify and Resolve Radio-TV Interference Problems".
This booklet is available from the U.S. Government Printing Office,
Washington, DC 20402, Stock No. 004-000-00345-4.
Warning-When connecting this device to your computer,
shielded interface cables must be used.

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  • Page 1 o 15.838 Class B computing device: information to user. This equipment generates and uses radio frequency energy and if not installed and used properly, that is, in strict accordance with the manufacturer's instructions, may cause interference to radio and television reception. It has been type tested and found to comply with the limits for a Class B computing device in accordance with the specifications in subpart J of Part 15 of FCC Rules, which are designed to provide reasonable protection against such...
  • Page 2 MFJ ENTERPRISES, INC. Model MFJ-1270C/1274C Packet Radio Controller Revision 10 SYSTEM MANUAL Fourth Edition (c) Copyright 1993, MFJ Enterprises, Inc.
  • Page 3 Requests for permission to copy or for further information should be addressed to MFJ Enterprises, Inc. P. O. Box 494, Mississippi State, MS 39762, USA. The information contained in this document has been carefully checked and is believed to be entirely reliable.

  • Page 4: Table Of Contents

    TABLE OF CONTENTS TABLE OF CONTENTS................iii INTRODUCTION ..................1 Items supplied with MFJ TNC package.........2 Optional items available for the MFJ TNC........3 COMPUTER INTERFACING ..............4 MFJ Terminal Software Starter Packs ...........4 Computer Interfacing with MFJ Starter Packs....5 Computer Interface without MFJ Starter Pack ....5 Serial Port Signals................5...
  • Page 5 First Steps ..................30 Basic Parameters Setup ...........31 Serial Port Configuration ...............31 Parity and Word Length ..........32 Echos ................33 New Lines and Line Wrapping........33 Tuning Indicator (MFJ-1274C) .............34 PACKET OPERATION ...............34 VHF Packet ..............34 A Connecting and Disconnecting Exercise ..35 Digipeating............37 Unsuccessful Connections.........38 Monitoring Channel Activity......39...
  • Page 6 What to Expect ..............95 Packet Picture Transfer..............96 Receiving Packet Pictures on Printer.......97 Packet Picture transfer to the computer screen ....97 Detail HF Packet Operation............98 Radio Setup for HF Packet Operation ......98 HF Packet Operation..............102 MFJ TNC KISS MODE AND HOST MODE .......109...
  • Page 7 Symptom: Modem won't calibrate or key transmitter....221 Symptom: Uncopyable transmitted or received packets ....222 Terminal Interface Troubleshooting.............222 Symptom: MFJ-TNC won't sign on to the terminal.......222 Symptom: The MFJ-TNC appears to be signing on but only gibberish is printed on the terminal..........223...
  • Page 8 MFJ-1270C/1274C MANUAL TABLE OF CONTENTS Symptom: The MFJ-TNC signs on OK but won't accept commands..................223 Symptom: The MFJ-TNC appears to have "locked-up" i.e. not responding to any commands............224 PACKET RADIO PROTOCOL..............225 Explanation of Protocol ..............225 Physical Layer ..............225 Data Link Layer...............226 HDLC Frames ..............226...
  • Page 9 MFJ-1270C/1274C MANUAL TABLE OF CONTENTS viii...

  • Page 10: Introduction

    The EPROM containing the MFJ TNC firmware is 256K bits. It is expandable to 512K bit or 1 Megabits giving the MFJ TNC a lot of room to grow in. A speaker jack lets you plug in a speaker and monitor both transmit and receive audio.

  • Page 11: Items Supplied With Mfj Tnc Package

    MFJ-1270C/1274C MANUAL INTRODUCTION A 20-pin header provided for the MFJ TNC to operate packet at 2400 or 9600 baud packet by simply pluging in an optional modem board. The MFJ-1270CT and the MFJ-1274CT already has a 2400 modem installed. If your MFJ TNC does not have the 2400 modem installed, it can be purchased separately (MFJ- 2400) and installed by you.

  • Page 12: Optional Items Available For The Mfj Tnc

    128K RAM IC for additional mailbox memory MFJ-45C 512K RAM IC for additonal mailbox memory MFJ-2400 2400 bps internal modem for packet MFJ-9600 9600 baud internal modem for packet The above items are available from MFJ dealers or directly from MFJ Enterprises, Inc. Page 3...

  • Page 13: Computer Interfacing

    Commodore C-64, C-128 or the VIC-20. Computer program\, see Terminal program In order to use the MFJ TNC with your computer, the computer must have an RS-232C serial port, or a TTL serial port and a program to support the serial or TTL port.

  • Page 14: Computer Interfacing With Mfj Starter Packs

    (Supports 2-level FAX) Computer Interfacing with MFJ Starter Packs If you are using one of the MFJ Starter Packs, you should use the cable provided to connect the MFJ TNC and your computer. Follow the instruction manual provided with the Starter Pack to operate the terminal program and to connect the MFJ TNC to your computer.
  • Page 15 The common ground for both data lines. Table 2-1. Serial port signals required by MFJ TNC . If your computer is listed below in Table 2-2, refer to the specific information in the following sections to connect your MFJ TNC to your computer. Manufacturer Model...

  • Page 16: Computers With Specific Serial Interfaces

    Note that pin 1 of the DP-9P connector is not connected inside the Macintosh or the MFJ TNC . If you use a shielded serial cable, which we recommend, connect both pin 1s to the shield and connect pin 1 of the MFJ TNC serial connector to Page 7...

  • Page 17: Commodore C64, C128 And Vic-20

    MFJ Enterprises, Inc. or from any MFJ dealer. The Starter Pack includes an interface cable from the MFJ TNC TTL port to the user I/O port on the Commodore computer. A terminal program is also included. To order, specify MFJ-1282 for software on disk or MFJ-1283 for software on tape.

  • Page 18: Ibm Pcjr

    PCjr to a standard RS-232C terminal connector. This cable attaches directly between the MFJ TNC and the PCjr. It is only about 3 inches long, however, so you may want to obtain a male-to- female RS- 232C extension cable, which should be readily available.
  • Page 19 Terminal Equipment (DTE). If this is the case for your computer, you will probably be able to simply wire pin 2 of the MFJ TNC connector to pin 2 of your computer's RS-232C port, pin 3 to pin 3 and pin 7 to pin 7. You can...
  • Page 20 MFJ-1270C/1274C COMPUTER INTERFACING Fig. 2-3. Serial port wiring with jumpers for auxiliary signals. Page 11...

  • Page 21: Other Computers With Non-Standard Serial Ports

    MFJ TNC serial port connector pin 7. The data line that sends data from the computer must be tied to the MFJ TNC connector pin 2. The pin on which your computer receives data on must be tied to the MFJ TNC connector pin 3.

  • Page 22: Apple Macintosh

    For the Apple II family of computers with Apple or third- party serial interface cards, you may use ASCII Express Pro, Hayes Smartcom IIe and DataCapture 4.0 for the MFJ TNC . There are others which may be compatible with the MFJ TNC , but have not been tested.

  • Page 23: Ibm Pcjr

    Also line 200 should read For J=0 to 64:T%(J)=J:NEXT. When making the connecting cable from TTL port of the MFJ TNC to the I/O port of the Commodore computer you may use the wiring information given on page 2-3 in this chapter. However, do not use pin E connection for this program.

  • Page 24: Radio Shack Color Computer

    MFJ TNC Serial Port Pin Functions This section describes the pins used on the MFJ TNC RS-232C serial port connector. It is intended for users with special applications requiring hardware handshaking. This information should not be needed by most users.

  • Page 25: Computer Baud Rate

    Bulletin Board system, since the AX.25 connection, analogous to a modem signal on the telephone, indicates the presence of a user. Shorting pin 1 and 2 of JMP1 on the MFJ TNC board will cause this output to always be true.

  • Page 26: Verifying Serial Port Operation

    Verifying Serial Port Operation Now that you have a terminal program and the hook-up cable for connecting the MFJ TNC to your computer, you are ready to verify that MFJ TNC will communicate with your computer. Turn on your computer. Load and run the terminal program.
  • Page 27 CAUTION: Only one of these switches may be ON at any time. *The MFJ TNC terminal baud rates of 300 and 19,200 is selected by a jumper on JMP 18 on the mother board. For 300 baud set the shorting jumper to position 2-3 and for 19,200 baud set the shorting jumper to position 1-2 (factory default).
  • Page 28 DISPLAY followed by a carriage return. You should see a lengthy list of items on your screen. This verifies the ability of the MFJ TNC to accept and respond to input from your computer. Your serial interface is now working.

  • Page 29: Radio Interfacing

    Pin 3 Push-to-talk, to allow the MFJ TNC to key your transmitter. Pin 4 Receive audio, from your receiver to the MFJ TNC . Pin 5 Squelch input (optional) to allow the MFJ TNC to detect activity on a shared-mode channel.

  • Page 30: Radio Port Connection

    Fig. 3-2 Radio Port Cable with Connector A 5-pin male DIN connector cable are provided with the MFJ TNC for wiring to the microphone connector for your radio. CHECK THIS CABLE WITH AN OHM METER TO IDENTIFY EACH WIRE BEFORE WIRING IT TO THE MIC CONNECTOR THAT FITS YOUR RADIO.
  • Page 31 If your HT has this type of microphone input, you can wire the microphone like the one shown in Fig. 3-3 or you can remove the cover of the MFJ TNC and install a shorting jumper at JMP L. Installing JMP L will eliminating the need of soldering "Cx"...

  • Page 32: Radio Interfacing Methods

    Method 1: Direct Connection to Microphone and Speaker For Method 1, shown in Fig. 3-5, the MFJ TNC 's audio will be fed directly into the microphone connector or similarly connected auxiliary jack, and the output of the MFJ TNC will be adjusted to give a proper modulation level. The receiver audio will be taken from an earphone plug or speaker jack and fed directly to the MFJ TNC .

  • Page 33: Transmit Audio Level Adjustment For Method I Interface

    Transmit Audio Level Adjustment for Method I Interface Connect your MFJ TNC and radio as shown in Fig. 3-5. Turn on the MFJ and computer and start your terminal program. Connect the radio to a dummy load and listen to the transmission with another nearby radio.

  • Page 34: Setting The Receiver Audio Input Level

    Setting the Receiver Audio Input Level The modem in your MFJ TNC is equipped with an advanced phase coherence type data carrier detector (DCD) with a sensitive tuning indicator. These can be used in combination to set the correct receive audio level for the modem and to optimize the DCD characteristics for the HF operation.
  • Page 35 A schematic of an external interface box is shown in Fig. 3-7. An interface box similar to the one shown in Fig. 3-7 is available from MFJ Enterprises, Inc. or from any MFJ dealers. Model No. is MFJ-1272B.

  • Page 36: Transmit Audio Level Adjustment For Interface Method Ii

    MFJ TNC to make adjustment of R(s), then you can increase the output level of the MFJ TNC by the transmit audio control on the left side of the TNC. The transmitting audio output of the radio port is factory set at 250 mV p-p.

  • Page 37: Receiver Audio Setting

    Set the volume control to the minimum volume position. The tuning indicator on the MFJ TNC should drift off to one side of the display and become stationary. It may drift enough to disappear off the end of the display.
  • Page 38 Volume of the monitor speaker can be adjusted by using the "Monitor" control on the left side of the MFJ TNC . If the internal amplifier of the MFJ TNC does not provide adequate volume you may use an external audio amplifier.

  • Page 39: Getting Started

    MFJ TNC . The Command Mode prompt cmd: will appear when the MFJ TNC is in Command Mode and is ready to accept your instructions. Before the MFJ TNC can be fully operational, some of the basic parameters must be set.

  • Page 40: Basic Parameters Setup

    K5FLU. Don't forget the <CR> at the end of the line. Your call sign will be used by the MFJ TNC as its "address." The MFJ TNC responds by telling you the previous value of the MYCALL parameter, and gives you a new Command Mode prompt.

  • Page 41: Parity And Word Length

    (We assume that you have set the baud rate correctly. See Chapter 2 if the baud rate needs to be changed.) The MFJ TNC 's default value is 8 bits and no parity. If your computer receives 8 bits as data, you may have to set space parity, since text may otherwise be interpreted as graphics or other special characters.

  • Page 42: New Lines And Line Wrapping

    (<LF>) whenever it displays a carriage return (<CR>). AUTOLF OFF to keep the MFJ TNC from also adding an <LF>. If you change equipment you may have to set AUTOLF ON to restore the MFJ TNC 's automatic linefeeds.

  • Page 43: Tuning Indicator (Mfj-1274C)

    If you are already familiar with the packet operation, then you may not want to perform this exercise. In this case go the other modes of operation in this chapter. Disconnect your radio from the MFJ TNC and turn off the MFJ TNC. Install the digital loopback jumper, JMP10. The analog loopback jumper, JMP7, should not be installed at the same time.

  • Page 44: A Connecting And Disconnecting Exercise

    To see how this works, you can have the MFJ TNC connect to itself. Since you have set the MFJ TNC up for digital loop-back, it will receive all packets that it sends.
  • Page 45 BREAK signals, you will have to change the character that returns you to Command Mode. See the section on "Special Input Characters," below. Now type a <CTRL-C>. The MFJ TNC doesn't echo the <CTRL- C>, but you should immediately see a Command Mode prompt. To return to Converse Mode, enter the command CONVERS: <CTRL-C>...

  • Page 46: Digipeating

    However there is a station located on the ridge, AD7I, which is in range of both you and N2WX. You direct the MFJ TNC to set up a connection to N2WX using AD7I as an intermediate digipeater as follows: cmd:CONNECT N2WX VIA AD7I You can specify a routing list of up to eight intermediate stations.

  • Page 47: Unsuccessful Connections

    You may have even mis- typed the other call sign. If the MFJ TNC does not get a re- sponse to its first connect packet, it will try again. You can control the number of attempts the MFJ TNC will make with the command RETRY.

  • Page 48: Monitoring Channel Activity

    Monitoring Channel Activity In addition to displaying messages from the station you are connected to, the MFJ TNC can allow you to monitor other packet activity on the channel. You can "read the mail," displaying packets between other stations. The MFJ TNC will also keep track of stations heard during a session.

  • Page 49: Your First Packet Qso

    MFJ TNC . Arrange to have another packet operator get on the air to help you get started. Make sure that your friend will be close enough to ensure solid copy, with no FM "popcorn"...

  • Page 50: Starting The Qso

    MFJ-1270C/1274C MANUAL BASIC OPERATION through the remainder of the examples in this chapter while you try out the MFJ TNC on the air. Starting the QSO You are ready to initiate a connect. For the sake of example, we will continue to use K5FLU in place of your call sign, and we will use WB0QRP for your friend's call.

  • Page 51: Digipeating

    Digipeating Now that you are on the air, you and your friend can try out the MFJ TNC 's digipeating capabilities. This is actually more interesting if you have at least three stations participating, but you can get the feel for it with two stations.

  • Page 52: Monitoring On The Air

    MFJ-1270C/1274C MANUAL BASIC OPERATION Monitoring on the Air This is a good time to try out the MFJ TNC 's monitor functions. While you and your friend are separately connected, type <CTRL-C> cmd:MONITOR ON cmd:MCON ON cmd:CONVERS You will be able to see both your "conversation" and your friend's conversation.
  • Page 53 <DELETE> or <BACKSPACE> characters, you can try both settings of the DELETE command and see which works. When you rub out a mis-typed character, the MFJ TNC will attempt to correct the screen display. This will work for most computers as well as display-type terminals.

  • Page 54: Hf Packet Basic Operation

    The redisplay-line character can be changed to any ASCII character by the command REDISPLA. If the MFJ TNC displays information faster than you can read it before it scrolls off the screen, you can halt the display by typing <CTRL-S>. To resume output from the MFJ TNC to your computer, enter <CTRL-Q>.
  • Page 55 The presence of a lock- detect signal is indicated by the Data Carrier Detect (DCD) LED. Each time DCD goes off the MFJ TNC will start a DWAIT interval which must elapse before the channel is considered to be available.

  • Page 56: Hf Packet Operation Hints

    The MFJ TNC is capable of receiving 2-level FAX. FAX receiving is possible only if you are using an optional terminal progrom provided by the MFJ Starter Pack. The MFJ TNC supports only the Weather FAX mode (120 line per minute) format.

  • Page 57: Fax Frequency

    FAX pictures to disk. FAX pictures saved on disk can be recalled for viewing on the screen at any time. MFJ terminal programs which support 2-level FAX receiving operation are as follows: MFJ-1284 for IBM PC and compatibles in 5-1/4" disk.

  • Page 58: Fax Station Frequencies

    MFJ-1270C/1274C MANUAL BASIC OPERATION FAX STATION FREQUENCIES Service Band Frequency (KHz) Weather 3,357.00 4,268.00 4,975.00 6,946.00 10,865.00 12,125.00 20,015 Photographs 10,680.70 17,673.90 18,434.90, 20,738.00 Other FAX Frequencies The following frequencies were obtained from Popular Communication Magazine: FREQUENCIES(KHz, USB) LOCATIONS 4,271.00 9,890.00 13,510.00 Halifax, Canada 8,502.00 12,750.00...

  • Page 59: Advanced Packet Operation

    Commands and other special keywords are shown in upper case; other text entered to the MFJ TNC is shown in upper and lower case. Special Characters The MFJ TNC recognizes a number of special characters for input editing, flow control, and other control functions.
  • Page 60 You can enter the code for a character in either hex (base 16) or decimal notation. The MFJ TNC displays character codes in hex. A number in hex notation is indicated by beginning the number with a $. The "digits" of a hex number represent multiples of powers of 16.

  • Page 61: Packet Operating Modes

    When the MFJ TNC is in Command Mode, the Command Mode prompt, cmd: is printed at the beginning of each input line. Note, however, that if the MFJ TNC has received and displayed packets, the prompt may have scrolled off the screen.

  • Page 62: Entering Data-Transfer Modes

    There are several ways to enter a data-transfer mode from Command Mode. You can type the command CONVERS or K to enter Converse Mode or the command TRANS or T to enter Transparent Mode, and the MFJ TNC will immediately enter the specified mode. The MFJ TNC will automatically enter a data-transfer mode if you are in Command Mode when a connection is completed.

  • Page 63: Converse Mode

    *** CONNECTED TO: <callsign> message is typed. If NEWMODE is ON, you will enter data- transfer mode immediately, without waiting for a successful connection. Any text sent to the MFJ TNC at this point will be queued up in packets which will wait for a successful connection before being sent.

  • Page 64: Transparent Mode

    REDISPLA re-display current line SENDPAC send current packet START, STOP user's flow control characters (sent to MFJ TNC) XOFF, XON MFJ TNC flow control characters (sent to to terminal) The following commands enable display features which are active in Converse Mode.
  • Page 65 Transparent Mode is a data-transfer mode like Converse Mode. In this mode there are no special characters, everything you type (or everything your compu- ter sends to the MFJ TNC) is sent over the radio exactly as it was received by the MFJ TNC.

  • Page 66: Flow Control

    The MFJ TNC's input buffer may fill up in Command Mode if you try to type too long a command. In Converse Mode the buffer may fill up for any of several reasons: you may be using a faster serial port baud rate than the radio data rate;...

  • Page 67: Xon/Xoff Flow Control

    CTS line. If you find that the MFJ TNC seems to lose data during file transfers, you should immediately suspect a flow control problem.

  • Page 68: Hardware Flow Control

    Transparent Mode. The command XFLOW OFF enables hardware flow control in Converse Mode and Command Mode. Your computer may receive as many as 2 characters after it signals the MFJ TNC to stop sending, since some characters may already be "in route" through serial I/O chips.

  • Page 69: Detail Vhf Packet Operation

    SSID. This is a number from 0 to 15, appended to the call sign with a dash: cmd:MYCALL W3IWI-3 If you don't specify the SSID extension, it will be 0, and the MFJ TNC won't explicitly show SSIDs that are 0. If you want to connect to a station with a SSID...
  • Page 70 *** connect request: <callsign> and send a "busy signal" rejection packet to the other station. If you receive a rejection packet from a station you try to connect to, your MFJ TNC will display *** <callsign> busy...

  • Page 71: Unattended Operations

    The MFJ TNC can operate unattended for extended periods of time. If you would like to have the MFJ TNC operate as a digipeater but not connect with a station, be sure to set DIGIPEAT ON and CONOK OFF. This is probably most useful when setting up a dedicated digipeater in a remote location.

  • Page 72: Packet Timing Functions

    TNCs. The version of AX.25 Level 2 protocol used by the MFJ TNC can be set to Version 2.0 with the command AX25L2V2 ON, or to Version 1.0 with the command AX25L2V2 OFF. Digipeating may not be successful if some MFJ TNCs are running Version 1.0 and some are running...
  • Page 73 The delay between transmitter keyup and the beginning of data transmission is controlled by the command TXDELAY. During the time the MFJ TNC is keying the transmitter but not sending data, it will transmit a synchronizing signal (flags).

  • Page 74: Packet Timing

    In order to avoid unnecessary packet retries, the MFJ TNC implements a collision-avoidance strategy which applies to all packets except those being digipeated. On the second and subsequent transmissions of a particular packet, the MFJ TNC waits an additional random time after detecting a clear channel Page 65...

  • Page 75: Radio Baud Rate

    Wait time = DWAIT * 10 + ( r * TXDELAY ) * 10 where r is a random number from 0 to 15. Thus, if your MFJ TNC is forced to re-transmit packets, you will occasionally hear a fairly long delay before transmission begins.

  • Page 76: Special Protocol Times

    The Bell-202 compatible modem is optimized for a 1200 baud radio data rate. The on-board modem is not useful at rates higher than 1200 baud. The MFJ TNC can provide data signals up to 9600 baud, but an external modem is required for operation above 1200 baud.
  • Page 77 MFJ-1270C/1274C MANUAL ADVANCED OPERATION The MFJ TNC's protocol is designed for setting up "circuits" between two stations. However it can also operate in a mode more suitable for a "net" or "round-table" discussion with several participants, although reliable reception of all transmissions by every station cannot be guaranteed.
  • Page 78 Disconnect acknowledgments are designated <UA>, and DM packets are <DM>. You can cause the MFJ TNC to "filter" certain characters from monitored packets with the command MFILTER. This allows you to remove, for example, form-feeds, bell characters, or extra <LF>s that may be necessary to the stations involved in a connection, but which may interfere with your display.

  • Page 79: Real-Time Clock And Time Stamping

    ADVANCED OPERATION Real-Time Clock and Time Stamping You can enable the MFJ TNC's real-time clock by setting the date and time with the command DAYTIME. Once you have set the clock, you can request the time by entering DAYTIME with no parameters. The format of date and time display is controlled by the command DAYUSA.

  • Page 80: How To Invoke Multi-Connect

    STREAMCALL STREAMDouBLe STREAMSWitch USERS This sets up the MFJ TNC to act just like a "normal" TNC does, that doesn't support multiple connections. The key to obtaining this traditional operation is to set USERS 1. How to Invoke Multi-Connect? If USERS is not 1, you are telling the MFJ TNC to allow multiple connections to your stations from other stations.

  • Page 81: Easy-Mail Mailbox

    MFJ TNC called MAILBOX. Being as the MAILBOX command in your MFJ TNC is already turned on, makes your Mailbox ready for use, as soon as your MFJ TNC is powered on. Anyone who operates AX.25 packet can access your mailbox by establishing a connection to your station by using the standard packet CONNECT command.
  • Page 82 MFJ Enterprises. With this real-time clock module installed in your MFJ TNC, the clock will continues to keep time even with the MFJ TNC turned off. You will not have to set your MFJ TNC's "DAYTIME" every time your MFJ TNC is powered up.
  • Page 83 MFJ-1270C/1274C MANUAL ADVANCED OPERATION commands. So, lets take a look at the functions of the Mailbox commands. The functions are as follows: Logout: This initiates a disconnect sequence from the Mailbox. Edit Message Header: This allows editing of the message header. This is necessary for the Forward and Reverse Forward functions of the Mailbox.
  • Page 84 MFJ-1270C/1274C MANUAL ADVANCED OPERATION will appear in the flag block closest to To: block in the message header. There are different types of flags are as follows: Messages with this flag set are all able to forwarded, providing all other criteria is met for a message to be forwardable). Only messages with the N flag set, trigger the "You have new mail!"...
  • Page 85 MFJ-1270C/1274C MANUAL ADVANCED OPERATION Allows you to kill messages which are addressed to you. This works in conjunction with the Y flag. In order to perform a Global Kill, first of all of the messages to be killed during this must have the Y flag set in the header.
  • Page 86 {0} Mailbox (B,E,H(elp),J,K,L,M,R,S,T) > Thus the {0} indicates the memory bank has been switched to bank #1. NOTE: The "M" function applies only to an MFJ TNC which have expanded mailbox memory. This command lets you read messages addressed to you. When you list the messages in the mailbox you notice an N flag next to the messages which you have not read.

  • Page 87: Mailbox Operation

    MFJ-1270C/1274C MANUAL ADVANCED OPERATION Paging SYSOP; any key aborts The Mailbox will page the SYSOP by ringing the SYSOP's terminal bell 30 times. If the SYSOP is at his or her terminal, the asterisk character will appear on the screen every time the terminal bell (CTRL-G) rings. If the SYSOP does not answer the Mailbox will send the message back to the user saying no answer.
  • Page 88 MFJ-1270C/1274C MANUAL ADVANCED OPERATION Now at this point all of the Mailbox are available to you. You may then type M to switch the memory bank of the Mailbox, K to kill a message, L to list all messages, R to read the messages, S to send a message, B to logout and disconnect from the Mailbox or H for the HELP menu.
  • Page 89 MFJ-1270C/1274C MANUAL ADVANCED OPERATION There are two (2) different ways to kill messages. The first is give in the example below: To kill a message in a particular slot type: K## <CR> Where the ## is the message number you want to kill.
  • Page 90 The From: column will contain the callsign of the person who left the message. The Subject: column will contain a brief message title. Note that the number of slots for an MFJ TNC without expanded memory is 30. For an MFJ TNC with the expanded mailbox memory installed the maximum slots per memory bank is 99.

  • Page 91: Additional Mailbox Features

    MFJ-1270C/1274C MANUAL ADVANCED OPERATION Where ## is the slot number of the message that you wish to read. C. The Mailbox will respond with the message from the slot specified. All messages read will be in the following format. Slot## To:...

  • Page 92: Forwarding

    Other MFJ TNC mailbox features are as follows: Forwarding The MFJ TNC Mailbox now has the ability to Forward mail to most full service and personal mailboxes. This feature allows you to compose your mail on your TNC, at your leisure, and then Forward the resulting messages for eventual delivery.

  • Page 93: Eliciting Reverse Forwards

    Mailbox Edit command. Please refer to the EDIT command in this manual. When the FO CALLSIGN is issued the MFJ TNC will initiate a connect request to the destination BBS. If the connection is successful the your mailbox will proceed to send the message to the destination BBS.

  • Page 94: Remote Sysop

    NTS type messages, and send them to another destination. The MFJ TNC also incorporates a new "bytes free" counter. It is updated as the mailbox fills or empties. It keeps up with the available RAM in multiple memory banks.

  • Page 95: Mailbox Messages

    The STA/MAIL LED of the MFJ TNC serves two functions. It lights when unacknowledged packets are pending during a packet connection. If you have mail waiting, the STA/MAIL LED will flash on and off if the MFJ TNC is not connected to another packet station.
  • Page 96 MFJ-1270C/1274C MANUAL ADVANCED OPERATION None found A parameterless Kill or Read command did not find any messages addressed to the user. No mail A parameterless read command did not find any mail addressed to user or due to mailbox being empty.

  • Page 97: Slotting And Acknowledgment Priority

    ADVANCED OPERATION Slotting and Acknowledgment Priority The SLOTTING AND ACKNOWLEDGMENT PRIORITY feature is installed in the MFJ TNC in an attempt to prevent or minimize packet collisions in a busy channel. Use of the optional SLOTTING and ACKNOWLEDGMENT PRIORITY procedures now in the MFJ TNC firmware significantly improve the reliability of packet radio connections on shared channels.

  • Page 98: Description

    MFJ-1270C/1274C MANUAL ADVANCED OPERATION Description The idea behind the prioritized acknowledgment (ACK) protocol is quite simple. The idea is to give ACKs priority access to the channel so that time is not wasted retrying packets that have already been correctly copied but for whatever reason, the ACK is not received within the time limit defined by the FRACK timer.

  • Page 99: New Parameters

    MFJ-1270C/1274C MANUAL ADVANCED OPERATION checked for sending an ACK. However, in this release DCD will still hold an ACK off the channel. Stations queued up to access the channel but waiting for a channel busy condition (DCD true) to clear, will start a slotted access procedure only AFTER enough time for a response frame to clear the channel has transpired (weather or not the response frame is detectable by the queued up station).
  • Page 100 This enables prioritized acknowledgments if turned on. If ACKprior is turned off and SLots (see below) is set to 0, this modification of the AX.25 protocol is effectively disabled. The MFJ TNC will behave like normal AX.25 protocol. Prioritized acknowledgments and slotted channel access can be enabled or disabled independently of one another.
  • Page 101 SLOTS n 0<=n<=127 This parameter determines how many sides are on the slot time dice. SLOTS represents an n+1 sided dice the MFJ TNC "throws" before transmitting. The SLOTS command allows any number of slots from 1 thru 127 to be defined.

  • Page 102: Other Related Parameters

    MFJ-1270C/1274C MANUAL ADVANCED OPERATION this way, the channel is reliably arbitrated and at the same time the overhead required for the arbitration is minimized so that overall throughput on the channel is maintained. The actual value used will depend on the average number of queued up stations there are on the channel during busy periods.

  • Page 103: Initial Parameter Settings Summary

    MFJ-1270C/1274C MANUAL ADVANCED OPERATION Note that these settings apply when everyone on the channel is running the new protocol. This assumes that all stations on the channel have both DWait and RESPtime set to 0. If you are running the new protocol on a channel where some of the stations have long RESPtime delays, those stations will not be able to successfully communicate with you after connecting.

  • Page 104: What To Expect

    MFJ-1270C/1274C MANUAL ADVANCED OPERATION DEAdtime ACKTime DWait RESPtime MAXframe FRACK What to Expect This modification to the protocol is compatible with stations using the current protocol in the following respect. A station using the new protocol will not degrade the channel for users of the current protocol. So there is nothing wrong with firing up the new stuff on a channel where the majority of the users aren't yet using it.

  • Page 105: Packet Picture Transfer

    MFJ-1284, is used. Receiving Packet Pictures on Printer Packet pictures data transmitted from the connecting packet station are received and data is sent directly to the printer attached to the MFJ TNC, without any Page 96...

  • Page 106: Packet Picture Transfer To The Computer Screen

    Note that you won't be able to call up PKTPIX until the connection is made. You must have the printer powered and selected before MFJ TNC will let you use the PKTPIX command.
  • Page 107 These levels are typically much higher than microphone levels. If you do adjust the output level of the MFJ TNC to a relatively high value for this type of application, do not operate the MFJ TNC with a VHF NBFM radio unless you take steps to assure that the audio level for the FM radio will not produce excessive deviation.
  • Page 108 MFJ-1270C/1274C MANUAL ADVANCED OPERATION to determine the actual operating frequency for band edge or netting purposes. Remember to consider that you will be occupying a few hundred Hz on either side of F(emission). NOTE: Regardless of the type of modem, whether or not the modem has audio...
  • Page 109 MFJ-1270C/1274C MANUAL ADVANCED OPERATION Radios which have provision for an auxiliary "narrow SSB" filter can have the 500 Hz bandwidth filter installed instead of the approximately 1.8 KHz wide "narrow" SSB filter. This will allow direct selection of the narrow filter for AFSK work when in SSB mode.

  • Page 110: Hf Packet Operation

    MFJ-1270C/1274C MANUAL ADVANCED OPERATION Make sure the MFJ TNC is in HF Packet mode and that the HF Packet modem has been selected. Set the audio output level so that the tuning indicator is responding to the background noise coming through the filter. This can be verified by observing whether or not the tuning indicator "follows"...
  • Page 111 This further degrades the effectiveness of CSMA. The DCD circuit in the MFJ TNC has been optimized for the HF packet mode. It can be adjusted to ignore background noise while still being able to promptly respond to a valid data carrier. It has a "hang time" feature that prevents DCD dropouts when short multipath hits occur or collisions put phase discontinuities in the received data carrier.
  • Page 112 The actual mechanics of operating the MFJ TNC in the HF packet mode are the same as for the VHF packet mode. The main differences that will be apparent to you will be the slower baud rates, the higher incidence of propagation related effects and QRM, and the requirement for accurate tuning.
  • Page 113 Find a clear frequency and monitor it for long enough to make sure it really is clear. Set "UNProto" to CQ if it isn't already. This is the default field for this parameter. Command the MFJ TNC into converse mode by typing either: K<CR> CONV <CR> Page 104...
  • Page 114 For as many <CR>s as you typed. Your friend will have little trouble finding you and tuning you in for the QSO. After the MFJ TNC finishes sending the string of CQ packets, listen for 5 to 10 seconds to allow a station to attempt to connect with you. If you don't get any nibbles, send another string of CQ packets.
  • Page 115 Occasionally strike a <CR> (2 a minute or so if DCD lets your packets clear the channel that fast) and wait for the MFJ TNC to get an opportunity to squeeze the packet into the activity on the channel. Allow some time after your packet has been sent for someone to attempt a connect with you and then send another CQ packet by typing a <CR>.
  • Page 116 0 (off) AX25V2 (off) CHECK 0 (off) CMSG (off) RETRY 0 (try forever , but NOT if unattended operation. This allows YOU to be the one to decide when or whether to give up rather than the MFJ Page 107...

  • Page 117: Mfj Tnc Kiss Mode And Host Mode

    MFJ TNC's digital system noise seen at the demodulator input. MFJ TNC KISS MODE AND HOST MODE One unique feature offered by the MFJ TNC is that it can be switched into KISS mode to run programs such as TCP/IP.

  • Page 118: Kiss Interface For Tcp/Ip

    Additional modification or replacement of firmware is not necessary. KISS enables the MFJ TNC to act as a modem for a host computer. Turning KISS on allows the MFJ TNC to run programs such as TCP/IP, MSYS and other programs which use the Serial Link Interface Protocal (SLIP).

  • Page 119: Operation Commands

    You will probably never change some of these parameters; however, one of MFJ's goals is to allow each user maximum flexibility to adapt the MFJ TNC to his environment.

  • Page 120: Command Name

    This reminds you of what you have done, and indicates that the value has been successfully changed. If you type something the MFJ TNC can't understand you will get an error message. If you type an unrecognized command, you will see the message ?EH.

  • Page 121: Default

    MFJ-1270C/1274C MANUAL COMMANDS For commands that set values, the MFJ TNC assumes a "most often used" or default condition. The defaults are the values stored in EPROM which are loaded into RAM when the system is first powered up, or when you give the RESET command.

  • Page 122: Parameters

    MFJ-1270C/1274C MANUAL COMMANDS command LCALLS. The second and later items in the list are optional, and you may separate the list items with blank spaces or with commas. These examples may help you to understand the explanations above. BEACON EVERY|AFTER n...
  • Page 123 Turning ACKPRIORiyty ON to enable prioritized acknowledgement. If ACKprior is turned off and SLots (see SLots) is set to 0, the modified AX.25 protocol is effectively disabled. The MFJ TNC will behave like normal AX.25 protocol. Page 114...
  • Page 124 0 - 250, in 10 ms intervals. The ACKTIME parameter controls a delay that occurs whenever any packets have been received by the MFJ TNC that are not addressed to the MFJ TNC. ACKTIME should be calculated by the radio channel baud rate, and by the keyup and keydown (TXDELAY and fixed timer, in TNC) delays.
  • Page 125 AUTOLF controls the display of carriage return characters received in packets as well as echoing those that are typed in. If the MFJ TNC's sign-on message lines appear to be typed over each other, you should set AUTOLF ON. If the MFJ TNC sign-on message appears to be double- spaced, you should set AUTOLF OFF.
  • Page 126 ASCII files, you should set AWLEN 7. If 8 bit words are transmitted to the MFJ TNC in Command Mode or Converse Mode, the eighth bit is normally removed, leaving a standard ASCII character, regardless of the setting of AWLEN.
  • Page 127 MFJ-1270C/1274C MANUAL COMMANDS When AX25L2V2 is ON, the MFJ TNC answers L2 UI frames with P and C set with either: RR if connected (regardless of rcvr flow control state), or DM if not connected. If retry limit is exceeded, or the MFJ TNC receives a "disconnected" response to a poll, the connection is ended.
  • Page 128 Note that the TAPR TNC 1 and other TNCs using the same version 3.x firmware interpret n in 120 ms intervals. The value you set on MFJ TNC for AXHANG will thus be 6/5 the value used by a TNC 1 user for the same hang time (when converting, round down to the nearest integer).
  • Page 129 MFJ-1270C/1274C MANUAL COMMANDS The connect request message is omitted during BBSMSGS mode. This should be most useful for preventing corruption of messages when forwarding with small frames. BEACON EVERY|AFTER n Mode: Packet Default: EVERY 0 Parameters: EVERY Send beacon at regular intervals.
  • Page 130 Puts MFJ TNC into Host Mode Takes MFJ TNC out of Host Mode When the BLP command is turned ON, the MFJ TNC is put into Host Mode. After you turn BLP ON and enter transparent mode the host code will run. Once...
  • Page 131 MFJ-1270C/1274C MANUAL COMMANDS You MUST set CONMODE to TRANS else the first time you're connected you'll lose the DLC connection! This is actually putting the MFJ TNC into Transparent mode. PARITY 0 The Parity must be set to 0 for Host Mode operations.
  • Page 132 MFJ-1270C/1274C MANUAL COMMANDS For example, a Bulletin Board program might set the beacon text to a message like this, updating the text after each connection: Mailbox on line. Messages for WB9FLW, AD7I, K9NG. To clear the BTEXT text without issuing the RESET command, use a % or &...
  • Page 133 MFJ-1270C/1274C MANUAL COMMANDS CALIBRA Mode: All CALIBRA is an immediate command, and is used to transfer control to the modem calibration routine. Calibration may be performed at any time without altering the current link state. Briefly, the commands available in the calibration routine are: <SPACE>...
  • Page 134 MFJ-1270C/1274C MANUAL COMMANDS CANLINE n Mode: Packet Default: $18 <CTRL-X> Parameters: 0 - $7F, specifying an ASCII character string code. This command is used to change the cancel-line input editing command character. The parameter n is the ASCII code for the character you want to type in order to cancel an input line.
  • Page 135 <BELL>*** Connected to: <callsign> When CBELL is ON a tone will also be heard on the external speaker. A speaker must be connected to the SPEAKER jack in the rear panel of the MFJ TNC, in order to hear this tone.
  • Page 136 In order to prevent this sort of lockup, the MFJ TNC will try to clean up the link if the specified time elapses without any packets being heard from the other TNC. The operation of this feature depends on the setting of AX25L2V2.
  • Page 137 The current stream may be connected to and disconnected from other stations. This command, when switched ON, forces the MFJ TNC to always maintain the current connection, even when frames to the other station exceed RETRY attempts to get an acknowledgment. RESTART and power off/on cycling will not affect this connected state.
  • Page 138 For example, if you have left your station running even though you don't want to operate just now, you might want to set CMSG ON to let people know that you can't talk when they connect to your MFJ TNC. When you are ready to operate, you would set CMSG OFF.
  • Page 139 This command controls whether the MFJ TNC will initiate a disconnect sequence after it is connected to. If CMSG is OFF, or CTEXT has no connected text, the MFJ TNC initiates a disconnect immediately upon receiving information or acknowledgement frames from the other station.
  • Page 140 If you initiate a connection with the CONNECT command, the control of Converse or Transparent Mode is determined by NEWMODE. If the MFJ TNC is already in Converse or Transparent Mode when the connection is completed, the mode will not be changed. If you have typed part of a command line when the connection is completed, the mode change will not take place until you complete the command or cancel the line.
  • Page 141 Converse Mode or Transparent Mode when the connection is successfully com- pleted. An error message is returned if the MFJ TNC is in a connected state, or is already attempting to connect or disconnect. If no response to the connect request occurs after the number of attempts specified by RETRY, the command is aborted and a message is typed.
  • Page 142 Stations attempting to connect to your MFJ TNC will be able to see that the station is up but not available for connection (it might still be useful as a digipeater).
  • Page 143 CONVERS Mode: All CONVERS is an immediate command, and will cause the MFJ TNC to exit from Command Mode into Converse Mode. Any link connections are not affected. Once in Converse Mode, everything you type is packetized and transmitted over the radio.
  • Page 144 If CR is OFF, the send-packet character is interpreted solely as a command to the MFJ TNC, not as data to be included in the packet, and furthermore, it will not be echoed to the terminal.
  • Page 145 MFJ-1270C/1274C MANUAL COMMANDS text Any combination of characters and spaces, up to a maximum length of 120 characters. CTEXT specifies the text of the packet to be sent after a connection is made, if CMSG is ON. The default text is an empty string, i.e., no message.
  • Page 146 The MFJ TNC's time is updated continuously as long as it is powered up. You must reset the date and time each time you turn on the MFJ TNC. If you don't do this, the commands CONSTAMP and MSTAMP will not enable time stamping.
  • Page 147 Date is displayed in the format mm/dd/yy. Date is displayed in the format dd-mm-yy. This command determines the format for the MFJ TNC's display of the date. If DAYUSA is ON, the standard U.S. format is used; if DAYUSA is OFF, the standard European format is used.
  • Page 148 MFJ-1270C/1274C MANUAL COMMANDS to come on the air properly after assertion of PTT (TXDelay) and the time required for the local station's squelch (if used) and TNC DCD circuits to allow generation of a "DCD true" signal in the local TNC. Ideally, once the proper value for this timer is ascertained, all stations on the channel will use the same value.
  • Page 149 If the retry count is exceeded while waiting for the other side to acknowledge, the MFJ TNC moves to the disconnected state. If a disconnect command is entered while the MFJ TNC is...
  • Page 150 MONITOR displays monitor parameters TIMING displays timing parameters HEALTH displays 25 counters* *The twenty five counters in the MFJ TNC are 16 bits wide, and are ALWAYS initialized to 0000 on power up or "RESTART". Page 141...
  • Page 151 MFJ-1270C/1274C MANUAL COMMANDS ASYFRERR: This is a health counter reflecting the number of hardware-detected asynchronous framing errors. Framing errors are not fatal. They merely indicate that the terminal attached to your MFJ TNC is not configured correctly with regard AWLEN/PARITY.
  • Page 152 The count may be useful in gauging system throughput. RCVDSABM: Each received SABM frame addressed to the MFJ TNC causes this counter to be increased by one. RXABORT: RXABORT is a count of the number of hardware- detected HDLC abort events.
  • Page 153 0 - 250, Specifying default wait time in 10 ms intervals. This value is used to avoid collisions with digipeated packets. The MFJ TNC will wait the default wait time after last hearing data on the channel before it begins its own keyup sequence, unless the MFJ TNC is waiting to transmit digipeated packets.
  • Page 154 `by the MFJ TNC. Characters are not echoed. This command controls local echoing by the MFJ TNC when it is in Command or Converse Mode. Local echoing is disabled in Transparent Mode. If you don't see your input on the display, you should set ECHO ON. If you see two copies of every character you type, you should set ECHO OFF.
  • Page 155 (rather than character translation) in monitored packets. FIRMRNR ON|OFF Mode: Packet Default: OFF FIRMRNR controls the handling of busy states by the MFJ TNC. Setting FIRMRNR ON improves channel efficiency, but is incompatible with earlier TNC-2 releases. The incompatibility is a result of vague protocol specifications.
  • Page 156 1 - 15, Specifying frame acknowledgment timeout in 1 second intervals. After transmitting a packet requiring acknowledgment, the MFJ TNC will wait for the specified frame acknowledgment timeout before incrementing the retry counter and sending the frame again. If the packet address includes relay requests, the...
  • Page 157 Full duplex mode is enabled. Full duplex mode is disabled. When full duplex mode is disabled, the MFJ TNC makes use of the Data Carrier Detect signal from the modem to avoid collisions, and acknowledges multiple packets in a single transmission with a single acknowledgment. When full duplex mode is enabled, the MFJ TNC ignores the DCD signal and acknowledges packets individually.
  • Page 158 Default: OFF Parameters: The MFJ TNC will "dither" the CON and STA LEDs. The MFJ TNC will control the CON and STA LEDs in normally. This command allows the user to redefine the functions of the two CPU controllable LEDs (i.e. the STAtus and CONnect LEDs).
  • Page 159 This command is used to enable or disable the sending of identification packets by the MFJ TNC. If HID is OFF, the MFJ TNC will never send an identification packet. If HID is ON, the MFJ TNC will send an identification packet every 9.5 minutes if the station is digipeating packets.
  • Page 160 The KISS interface is installed in firmware of the MFJ TNC. KISS enables the MFJ TNC to act as a modem for a host computer. Turning KISS ON allows the MFJ TNC to run programs such as TCP/IP and other programs which use the Serial Link Interface Protocol (SLIP).
  • Page 161 MFJ-1270C/1274C MANUAL COMMANDS If KISS is turned ON and you have problem revert the MFJ TNC back to normal AX.25 operation with the above procedure, you can also turn KISS OFF by removing JMP5 on the mother board. Reinstall JMP5 after a few minutes.
  • Page 162 If your computer or terminal does not accept lower case characters it may react badly if the MFJ TNC sends such characters to it. This command allows you to translate all lower case characters received in packets, as well as messages from the MFJ TNC, to upper case.
  • Page 163 MFJ-1270C/1274C MANUAL COMMANDS When LFADD is ON and the ASCII or Packet mode is selected, MFJ TNC will append an ASCII line feed character, $0A, to the transmission immediately after a carriage return is sent. LFADD should usually be switched OFF as the vast majority of TNCs (including the MFJ TNC) are configured to automatically go to a new line whenever a carriage return is printed.
  • Page 164 MFJ-1270C/1274C MANUAL COMMANDS the Y flag. K ## Kills the message in slot nn, depending of the setting of the Y flag. Remote users may only kill message addressed to them or originated by them. the local SYSOP,however, can kill all messages.
  • Page 165 OFF, only otherwise eligible packets (as determined by the BUDLIST and LCALLS commands) sent by other TNCs in the unconnected mode are displayed. This is the normal manner of operation when this MFJ TNC is being used to talk to a group of TNCs all of which are unconnected.
  • Page 166 Signifying a number of packets. MAXFRAME sets an upper limit on the number of unacknowledged packets which the MFJ TNC can have outstanding at any one time. This is also the maximum number of contiguous packets which can be sent during any given transmission.
  • Page 167 Monitor mode is off while the MFJ TNC is connected. If MCON is ON, the MONITOR command will enable monitoring while your MFJ TNC is connected to another TNC. If MCON is OFF, the display of monitored packets is suspended when a connect occurs, and is resumed when the TNC is disconnected.
  • Page 168 MHEARD Mode: Packet MHEARD is an immediate command. It causes the MFJ TNC to display the list of stations that have been heard since the last time the command MHCLEAR was given. Stations that are heard through digipeaters are marked with a * in the heard log.
  • Page 169 Mode: All MODE is a immediate command. The MODE command selects which mode the MFJ TNC will be operating in. The MODE command is followed by two characters which denote the mode selected. See Chapter 4 for a more detailed discussion of the MODE command.
  • Page 170 Monitoring of all packet activity is enabled. Monitoring of all packet activity is disabled. If MONITOR is ON and the MFJ TNC is not in Transparent Mode, packets not addressed to your MFJ TNC may be displayed. The addresses in the packet are displayed along with the data portion of the packet, e.g.:...
  • Page 171 MFJ-1270C/1274C MANUAL COMMANDS The format of the monitor display is controlled by HEADERLN. If you want to see the station addresses on a separate line from the text, you can set HEADERLN ON. MRPT enables monitoring of the digipeater route as well as source and destination addresses for each packet.
  • Page 172 MFJ-1270C/1274C MANUAL COMMANDS MSTAMP ON|OFF Mode: Packet Default: OFF Parameters: Monitored frames are time stamped. Monitored frames are not time stamped. This command enables time stamping of monitored packets. The date and time information is then available for use for automatic logging of packet activity or other computer applications.
  • Page 173 Callsign of your MFJ TNC. 0 - 15, an optionally specified sub-station ID (SSID). This command tells the MFJ TNC what its callsign is. This callsign will be placed in the FROM address field for all packets originated by your MFJ TNC. It will accept frames with this callsign in the TO field and relay frames with this callsign in the digipeat field.
  • Page 174 Switching to data transfer mode occurs at time of connection and no return to command mode occurs at disconnection. The NEWMODE command may be used to select the way the MFJ TNC behaves when connections are made and broken. Page 165...
  • Page 175 MFJ-1270C/1274C MANUAL COMMANDS If NEWMODE is OFF, the MFJ TNC will remain in Command Mode after you issue a CONNECT command until a connection is actually established. When the connection is established, the MFJ TNC will enter Converse Mode or Transparent Mode, depending on the setting of CONMODE.
  • Page 176 The MFJ TNC will switch modes in accordance with the setting of NEWMODE. When NOMODE is ON, the MFJ TNC will never change between CONVERSE or TRANSPARENT mode to COMMAND mode (or vice-versa) on its own. Only user commands (CONV, TRANS, or ^C) may change the type in mode.
  • Page 177 MFJ-1270C/1274C MANUAL COMMANDS NUCR ON|OFF Mode: Packet Default: OFF Parameters: <NULL> characters are sent to the terminal following <CR> characters. <NULL> characters are not sent to the terminal following <CR> characters. This command causes transmission of <NULL> characters (ASCII code $00), producing an effective delay following any <CR>...
  • Page 178 0 - 255, Specifying the maximum length of the data portion of a packet. The value 0 is equivalent to 256. The MFJ TNC will automatically transmit a packet when the number of input bytes for a packet reaches n. This value is used in both Converse and Transparent Modes.
  • Page 179 MFJ-1270C/1274C MANUAL COMMANDS PACTIME EVERY|AFTER n Mode: Packet Default: AFTER 10 Parameters: 0 - 250, Specifying 100 ms intervals. EVERY Packet timeout occurs every n*100 milliseconds. AFTER Packet timeout occurs when n*100 milliseconds elapse with no input from the computer or terminal.
  • Page 180 MFJ-1270C/1274C MANUAL COMMANDS PASS n Mode: Packet Default: $16 <CTRL-V> Parameter: 0 - $7F, Specifying an ASCII character code. This command selects the ASCII character used for the "pass" input editing command. The parameter n is the ASCII code for the character you want to type in order to include the following character in a packet or text string.
  • Page 181 Packets are accepted for display despite CRC errors if they consist of an even multiple of 8 bits and up to 339 bytes. The MFJ TNC will attempt to decode the address field and display the callsign(s) in the standard monitor format, followed by the text of the packet.
  • Page 182 The effect of this command is the same as turning the MFJ TNC OFF then ON again. RESTART does not cause a reset of the parameters in bbRAM. See also the RESET command.
  • Page 183 MFJ-1270C/1274C MANUAL COMMANDS You can type this character to cause the MFJ TNC to retype a line you have begun. When you type the redisplay-line character, the following things happen: First, type-in flow control is temporarily released (if it was enabled). This displays any incoming packets that are pending.
  • Page 184 The time between retries is specified by the command FRACK. A value of 0 for n specifies an infinite number of retries. If the number of retries is exceeded, the MFJ TNC goes to the disconnected state (with an informative message if not in Transparent Mode). See also the FRACK command.
  • Page 185 Correct operation of RXBLOCK is dependent on the AWLEN parameter getting set to 8 (bits) since the character FF hex marks the beginning of a received data unit header. When RXBLOCK is ON, data from other stations will be sent from the MFJ TNC in the following format: -----------------------------------------------------------------------------------------------...
  • Page 186 MFJ-1270C/1274C MANUAL COMMANDS RXCAL is an immediate command. When invoked, the MFJ TNC generates test signals (based on CALSET -- see below) that are used by the internal tuning software to align the demodulator components. To use the RXCAL feature, Align the modulator components as described in the owners manual.
  • Page 187 This is a map of the physical locations of the adjustment potentiometers on the MFJ TNC circuit board. They are shown as they appear when looking down on top of the board with the board oriented so that the rear panel connectors are to the left.
  • Page 188 MFJ-1270C/1274C MANUAL COMMANDS RVfALWAY ON|OFF Mode: Mailbox Default: ON Parameters: ON Initiates forwards and reverse forwards of all forwardable messages. OFF Mailbox ignores Forward and NODEforw commands. The setting of RVFALWAY(s) controls whether the TNC will initiate forward events (FORWARD, NODEFORW) in the absence of forwardable messages. If OFF, the TNC will ignore FORWARD and NODEFORW commands entered in the absence of forwardable messages.
  • Page 189 MFJ-1270C/1274C MANUAL COMMANDS For ordinary conversation, you will probably set SENDPAC $0D and CR ON. This causes packets to be set at natural intervals, and causes the <CR> to be included in the packet. If you have set CPACTIME ON, you will probably set SENDPAC to some value not ordinarily used (say, <CTRL-A>), and set CR OFF.
  • Page 190 MFJ TNC to the terminal. You can enter the code in either hex or decimal. This is the character you will type to halt the MFJ TNC's typing so that you can read text before it scrolls off your display.
  • Page 191 MFJ-1270C/1274C MANUAL COMMANDS If the same character is used for both the User Restart and User Stop characters the MFJ TNC will alternately start and stop transmission upon receipt of the character. STREAMCA ON|OFF Mode: Packet Default: OFF Parameters: Callsign of other station displayed.
  • Page 192 When operating with multiple connections, this is useful for differentiating between STREAMSWitch characters received from other stations and STREAMSWitch characters internally generated by your MFJ TNC. NOTE: The STREAMSWitch character must NOT be one of the stream letters (A - J) for this command to function properly.
  • Page 193 Parameters: $FF, usually specifying an ASCII character code. This command selects the character used by both the MFJ TNC and the user that a new "stream" (connection channel) is being addressed. The character can be PASSed in CONVERS mode. It is always ignored as a user-initiated stream switch in TRANSPARENT mode, and flows through as data.
  • Page 194 MFJ-1270C/1274C MANUAL COMMANDS 0 - 60, Specifying 1 minute intervals The TIMEDMIN parameter is compared against the minutes register of the real time clock to determine when the TIMEDCMD string is sent to the command interpreter. Setting this parameter to 60 disables the feature. Combined with the TIMEDCMD string, the user may configure his TNC to perform hourly automatic forwards and reverse forwards.
  • Page 195 TRANS Mode: Packet Immediate Command This is an immediate command. It causes the MFJ TNC to exit from Command Mode into Transparent Mode. The current link state is not affected. Transparent Mode is primarily useful for computer communications. In this mode, the "human interface"...
  • Page 196 When used with no argument: if the MFJ TNC has an outstanding unack- nowledged frame, it will return the current number of tries; if the MFJ TNC has no outstanding unacknowledged frames, it will return the number of tries required to obtain an acknowledgment for the previous frame.
  • Page 197 Parameters: 0 - 120, Specifying 10 ms intervals. This value tells the MFJ TNC how long to wait after keying up the transmitter before sending data. Some startup time is required by all transmitters to put a signal on the air; some need more, some need less. In general, crystal controlled...
  • Page 198 Note that the TAPR TNC 1 and other TNCs using the same firmware interpret n in 40 ms intervals. The value of TXDELAY on MFJ TNC will thus be 4 times the value used by a TNC 1 user to give the same delay time.
  • Page 199 Unless TRFLOW is also ON, only hardware flow control is available to the computer or terminal to control output from the MFJ TNC. Note that if the MFJ TNC Restart and MFJ TNC Stop characters are set to $00, hardware flow control will always be selected regardless of the setting of TXFLOW.
  • Page 200 TXUIFRAME ON|OFF Mode: Packet Default: ON TXUIFRAME is used to tell the MFJ TNC what to do with unconnected information left in its buffers. When this parameter is ON, all unconnected data are transmitted as "UI" (unconnected) frames. This command should be OFF for bulletin-board stations as it precludes the unnecessary transmission of text that occurs when the BBS user disconnects -and- unacknowledged packets remain.
  • Page 201 XON/XOFF flow control is disabled and hardware flow control is enabled. If XFLOW is ON, the computer or terminal is assumed to respond to the MFJ TNC Restart and MFJ TNC Stop characters set by XON and XOFF. If XFLOW is OFF, the MFJ TNC will communicate flow control commands via RTS.
  • Page 202 MFJ TNC generates and sends packets as requested, but does not key the radio PTT line. You might use this command to insure that your MFJ TNC does not transmit in your absence if you leave it operating to monitor packet activity. This command can also be used for testing using loopback or direct wire connections when PTT operation is not relevant.
  • Page 203 This character would ordinarily be set to <CTRL-Q> for computer data transfers. If you are operating your station in Converse Mode, and there is some chance that you might fill up the MFJ TNC's buffers, you might set this character to <CTRL- G> ($07), which rings a bell on many terminals.
  • Page 204 Checksum XXX cmd: This is the sign-on message that appears when you turn ON your MFJ TNC or when you issue the RESET command. The release number will be updated whenever the firmware is changed. The checksum is a hex number which you can compare against the correct checksum given for the firmware version you are using.
  • Page 205 MESSAGES Mode. You can type the redisplay-line character (set by REDISPLA) to retype the prompt. Whenever you change the setting of one of the MFJ-TNC's parameters, the previous value will be displayed. This confirms that the MFJ TNC properly interpreted your command, and reminds you of what you have done.

  • Page 206: Mailbox Messages

    MFJ-1270C/1274C MANUAL MESSAGES Cannot, not yours This message occurs when a remote user attempts to kill a message which isnot his, or he tries to read personal message by or for someone else. The SYSOP can read or KILL any message in the Mailbox system.

  • Page 207: Command Mode Error Messages

    MESSAGES Command Mode Error Messages If you make a mistake typing a command to the MFJ-TNC, an error message will be printed. You may see any of the fol- lowing messages depending on the type of error you have made.
  • Page 208 MFJ-1270C/1274C MANUAL MESSAGES ?not enough You didn't give enough arguments for a command that expects several parameters. ?not while connected You attempted to change MYCALL or AX25L2V2 while in a connected or connecting state. ?range A numeric argument for a command was too large.

  • Page 209: Link Status Messages

    You can always interrogate the link status by giving the CONNECT command without parameters. If you attempt a connection when your MFJ TNC is not in the disconnected state, the MFJ TNC will display the link status but will take no other action. The following messages appear in response to the CONNECT command.
  • Page 210 The MFJ TNC will inform you whenever the link status changes. The link status may change in response to a command you give the MFJ TNC (CONNECT or DISCONNE), a connect or disconnect request packet from another station, a disconnect due to the retry count being exceeded, an automatic time-out disconnect (CHECK), or a protocol error.
  • Page 211 This message indicates that your connect request was rejected by a DM packet (busy signal) from the other station. The MFJ TNC will reject a connect request if CONOK is OFF, or if it is already connected to another station, or the connect request is from a station with a totally blank callsign.
  • Page 212 MFJ-1270C/1274C MANUAL HARDWARE HARDWARE This chapter details the specifications and the functional description of the MFJ- TNC hardware design. MFJ-TNC Specifications Processor CMOS Z-80A Clocks Processor master clock input frequency: 4.9152 MHz User Port Clock: Switch selectable at 16x baud rate.

  • Page 213: Hardware

    (character delete, line delete, input packet delete, output packet delete and redisplay input) via special characters trapped by the MFJ TNC. Escape to command mode via special character or BREAK signal. Optional use of packet completion timer as in Transparent mode.

  • Page 214: General Description

    The battery back-up feature enables the MFJ-TNC to "remember" these values when power is off so you don't have to enter them every time you want to operate.

  • Page 215: Oscillator

    MFJ-1270C/1274C MANUAL HARDWARE Dividers and Baud-rate Generator U10e, U10f, U4a, U4b, U1, U30 ad U31 provide clock outputs derived from the oscillator. Electronics switches within U30 and U31 provide all the terminal baud rate and the RF baud rate under software command.

  • Page 216: Serial Interface

    MFJ-1270C/1274C MANUAL HARDWARE permanent storage of user-supplied information (such as your callsign). Selector U12b acts as a RAM address decoder, with RAM starting at address 8000 hex. The sections of CMOS switch U13 are used to insure that the RAM is not selected when main power is removed.
  • Page 217 TNC is switched off. JMP5 provides a means of disconnecting the negative side of the lithium battery for MFJ-TNC maintenance. U2 and associated components form a charge-pump voltage inverter which generates an unregulated negative supply for the RS-232C drivers.

  • Page 218: Modem

    DTR is asserted. If the terminal is not ready to receive data, it should negate (make false) DTR to the MFJ- TNC . Thus, data flow from the MFJ-TNC to the terminal is controlled by the use of the DTR line.
  • Page 219 7- or 8-bit character lengths. Setting these terminal parameters is discussed in Chapter 4. If you want to interface your MFJ-TNC with a device configured as DCE, such as a telephone modem or another TNC, a so-called "null modem" cable may be constructed to interchange the data and handshake signals.

  • Page 220: Jumper Functions

    MFJ-1270C/1274C MANUAL HARDWARE Table 8-1: Jumper Function Jumper # Position Function JMP1 Pin 1 & 2 !DCD (RS-232C) stays on Pin 2 & 3 !DCD (RS-232C) stays off OFF (default) !DCD reflects connect status JMP2 Pin 1&2 (default) 4.92 MHz CPU clock Pin 2 &...
  • Page 221 You will not have to reset the clock everytime you turn the MFJ-TNC on. MFJ provides the user with a TTL Level Input/Output port. This port is usable with computers which cannot make use of the Serial Input/Output RS-232c port.
  • Page 222 External Modem Interface Connector - J14 Modem Disconnect Header- J4 The modem disconnect header, J4, on the MFJ-TNC PC board is provided for using an external modem with the MFJ-TNC. This allows use of higher-speed modems, such as 9600 baud, or more sophisticated, higher-performance modems for OSCAR or other uses.
  • Page 223 SIO RTS Output This signal is used for transmitter activation. The SIO will pull this output low when the MFJ-TNC wants to transmit; otherwise it will remain high. This pin is normally jumpered to pin 6 when the on-board modem is used.
  • Page 224 This pin is normally jumpered to pin 13 when the on-board modem is used. Pin 15 MFJ-TNC Ground Reference This pin ties to the MFJ-TNC digital ground system, at the SIO. Pin 16 Turbo LED output This pin is used to connect the Turbo LED on the mother board to the external modem board.

  • Page 225: Hf Tuning Indicator

    RFI protection. HF Tuning Indicator The MFJ-TNC has a built-in tuning indicator for HF operation. It is set for a center frequency of 2210 Hz. The incoming audio frequency is centered at 2210 Hz. This is indicated by one or two of the center most LEDs brightly lit. When you are tuned to a lower center frequency, the LED to the left of center lights.
  • Page 226 TROUBLESHOOTING WARNING: Never remove or insert an IC with power on! Your MFJ-TNC is a complex piece of electronic equipment. Servicing must be approached in a logical manner. The best preparation for troubleshooting is to study the detailed hardware description in Chapter 7. While it is not possible to present all possible problems, symptoms and probable cures, this section of the manual will give direction to troubleshooting based on our experience.

  • Page 227: Troubleshooting

    MFJ-1270C/1274C MANUAL TROUBLESHOOTING pin 5. If -V is more negative than - 7 volts (i.e., normal), but the -5 volt regulated voltage is wrong, check the negative regulator components U3, Q2, R5, R6, R7, R8, CR6, C10, C11 and C158. If both -V and the -5 volt regulated voltage are wrong, look for shorts.

  • Page 228: Symptom: Tnc Appears Dead

    TROUBLESHOOTING While the steps described above may seem obvious, careful inspection often will point to the problem or give significant clues as to the probable area of the MFJ- most suspect. After the above inspection has been completed and apparent problems are dealt with, it is time to proceed to more specific analysis.

  • Page 229: Symptom: Modem Won't Calibrate Or Key Transmitter

    MFJ-1270C/1274C MANUAL TROUBLESHOOTING U21 pin 36, and the INT line on pin 16. Each of these lines should show activity, and if any line is quiet this is a sign of trouble. Logic lines that show no activity may often be traced to a short on the pc board, probably due to a solder splash or bridge.

  • Page 230: Terminal Interface Troubleshooting

    Make sure that JMP 8 is ON. Terminal Interface Troubleshooting If you can't get the MFJ-TNC to sign on and accept data from your terminal or computer, the problem may be in the RS-232C interface. The troubleshooting guide below is provided as an aid to help in resolving problems that may be related to the RS-232C port.

  • Page 231: Symptom: The Mfj-Tnc Signs On Ok But Won't Accept Commands

    This indicates that some combination of the data rate (baud rate), parity option, or number of start and stop bits are not set the same at the MFJ-TNC and at the terminal. If possible, set your terminal to 1200 baud. Also verify that the terminal is set for eight data bits, no parity, and 1 stop bit.

  • Page 232: Symptom: The Mfj-Tnc Appears To Have "Locked-Up" I.e. Not

    This may be due to some invalid parameters having been stored in the memory. Try turning the MFJ-TNC off and disconnect JMP 5 on the MFJ-TNC board. This will disconnect the memory back-up circuit and allow the memory to be erased.

  • Page 233: Packet Radio Protocol

    RF links. The physical layer of the MFJ-TNC is described in Chapter 7, Hardware. It is compatible with the various TNCs currently available to radio Amateurs. The actual modem interface is compatible with the Bell 202 standard which is similar to the CCITT V.23 standard.

  • Page 234: Data Link Layer

    MFJ-1270C/1274C MANUAL PACKET PROTOCOL with the Bell 202 standard should be compatible with the MFJ-TNC, at least at level one of the ISO reference model. Data Link Layer The duty of the Data Link layer is to supply an error-free stream of data to higher levels.

  • Page 235: Ax.25 Level Two

    FCS. There is virtually no chance of an undetected bad frame using this method. This satisfies the level two task of bad data detection. The communications chip used in the MFJ-TNC is a Zilog 8440 SIO operating in conjunction with a two-chip "state machine" which is used to recover the data clock.
  • Page 236 It is used for beacon frames, for automatic identification packets, and for sending information frames when the MFJ-TNC is not connected to another TNC, e.g., CQ and QST activities. The exact specifications for AX.25 are supplied in the ARRL publication Amateur Packet-Radio Link-Layer Protocol, AX.25 Version 2.0.
  • Page 237 MFJ-1270C/1274C MANUAL PACKET PROTOCOL Code Abbrv Frame Type Receive Ready Receive Not Ready Reject Unnumbered Information Disconnected mode SABM Connect request DISC Disconnect request Unnumbered Acknowledge FRMR Frame reject even Any frame ending in an even number (including $A, $C, and $E) is an information frame.

  • Page 238: Channel Use And Timing Functions

    (The RF carrier is not normally detected; however, an input is available on the MFJ- radio interface connectors to allow such an input.) In order to make...
  • Page 239 MFJ-1270C/1274C MANUAL PACKET PROTOCOL activity, frame length, whether the packet is being digipeated, and other time- related factors. If no ACK is received, the packet must be re-sent. If the unACKed frame was lost due to a collision, the assumption is that there is at...

  • Page 240: Channel Flow Control

    Whenever a TNC transmitting data received from the serial port over the link runs out of temporary buffer space, the serial port will be halted by an XOFF character or CTS signal. In the MFJ-TNC implementation this happens whenever there are 7 packets built and less than 210 characters left in the buffer for input from the serial port.
  • Page 241 MFJ-1270C/1274C MANUAL APPENDIX A: RADIO HOOKUP Page 232...

  • Page 242: Radio Hookup

    NOTE: The radio connection information listed in the above chart is believed to be accurate. However, you should CHECK the ACCURACY of this information with the INSTRUCTION MANUAL of your radio. MFJ Enterprises, Inc. is not responsible for any inaccuracy of information listed in the above chart.

  • Page 243: Modem Calibration

    MFJ-1270C/1274C MANUAL APPENDIX B: CALIBRATION MODEM CALIBRATION The MFJ TNC is factory calibrated to operate to within factory guidelines. If it becomes necessary to re-calibrate the modem, then the following procedure is provided. Modulator and Demodulator Frequency Calibration Here we present two (2) Modulator and Demodulator calibration methods.

  • Page 244: Method Ii

    MFJ-1270C/1274C MANUAL APPENDIX B: CALIBRATION Test equipment needed: Frequency Counter and probe and oscilloscope with probe. Install push-on jumpers on JMP 4 and JMP 7. Verify a push-on jumper is installed on JMP 8. In the following procedure all frequencies are to be set to within +/- 2 HZ.

  • Page 245: Set Modulator Tones Using Built-In Calibration Software

    This tells the CPU what tone frequency you are trying to achieve. A table of CALSET numbers to use for the various "standard" modem tone frequencies will be included at the end of this procedure. Command the MFJ-TNC into calibrate mode by typing "CALI followed by a <CR>". Page 236...

  • Page 246: Demodulator Center Frequency Alignment

    U16, pin 9 reads + 5 volts. 14. Adjust R105 carefully until both the "CON" and "STA" LEDs on the front panel of the MFJ-TNC are lit. One of the leds may flicker slightly. This is normal. 15. Type a "Q". This exits the MFJ-TNC from calibrate mode to command mode.

  • Page 247: Tuning Indicator Alignment

    MFJ-1270C/1274C MANUAL APPENDIX B: CALIBRATION NOTE: The threshold control on the MFJ-TNC must be set to a position which will allow the DCD circuit to function properly. A setting approximately 1/3 to 1/2 of the total range starting from maximum CCW should be adequate.

  • Page 248: Mfj-Tnc Adjustment Location Map

    This is a map of the physical locations of the adjustment potentiometers on the MFJ-TNC circuit board. They are shown as they appear when looking down on top of the board with the board oriented so that the rear panel connectors are to the left.
  • Page 249 MFJ-1270C/1274C MANUAL APPENDIX B: CALIBRATION Calset Values for Various Modulator Tone frequencies Tone CALSET # Adjust Modem / Remarks 2125 R106 HF Packet Fc = 2210 Hz 2295 R105 170 Hz shift 1300 Packet / Fc = 1700 Hz, 800 Hz shift.

  • Page 250: Audio Output Calibration

    Transmit audio adjustment is accessible from the outside thru screw driver adjustment holes on the left side of the MFJ-TNC. It is not necessary to remove the cover. Most often audio output level of the MFJ-TNC can be set simply by monitoring the transmitting audio with a connecting station.
  • Page 251 MFJ-1270C/1274C MANUAL APPENDIX C: AUDIO OUTPUT 10. Press the space bar and again measure the peak to peak voltage at J9 pin 4.The audio level should not change.(Both mark and space audio should be at the same level.) 11. Remove the jumpers from JMP 4 and JMP7.

  • Page 252: Hf Radio Alignment

    APPENDIX D: ALIGNMENT HF RADIO ALIGNMENT If you have determined that it is necessary to realign the MFJ-TNC modem center frequency to your radio filter center frequency, one of the following 2 methods should be used to make the radio filter center frequency (Fc) determination.
  • Page 253 MFJ-1270C/1274C MANUAL APPENDIX D: ALIGNMENT Measure this tone frequency with the counter. Record this value as F(low). Slowly and carefully tune the receiver so that the tone frequency is increasing. Find the point where the signal is reduced by 1 S-UNIT from the peak value reached near the center of the filter passband.

  • Page 254: Mfj-Tnc 2400 Packet Operation

    The MFJ-TNC will be set to 2400 packet operation. The TURBO LED will light. Note that if your MFJ- TNC is not equipped with the 2400 modem, the TURBO LED will not function and you will not be able to operate 2400 packet.

  • Page 255: Transmit Audio Setting

    2400 modem board. Transmit audio for the 1278BT is pre-set at the factory to match the audio level of the 1200 modem on the MFJ-TNC mother board. Once the 1200 and the 2400 transmit audio are set to the same level, then you may adjust the audio level going into your radio by using the "Transmit Audio"...

  • Page 256: Jumper Functions And Locations

    MFJ-1270C/1274C MANUAL APPENDIX F: JUMPERS JUMPER FUNCTIONS AND LOCATIONS The MFJ-TNC mother board has many jumper connectors. Each jumper connector has a special function. The Jumper Function chart in this appendix will help in identifying each jumper function. Figure G-1 will help in locating the jumper connectors easily.
  • Page 257 Speaker Connect Tone Enable Speaker Connect Tone Disable When JMP23 is shorted, it will RESET the MFJ-TNC. This means that all parameters will be reset to the default values. This is the same as removing the bbRAM battery except it is much quicker. DO NOT SHORT THIS JUMPER...
  • Page 258 MFJ-1270C/1274C MANUAL APPENDIX F: JUMPERS Fig. G-1: Jumper Connector Location Page 249...

  • Page 259: Command Summary

    AUTOLF ON|OFF Packet Determines the way the <CR>characters are displayed. 6-13 AWLEN Defines the word length used by the MFJ TNC 's RS- 6-14 232 port. AX25L2V2 ON|OFF Packet Determines the use of AX.25 Level 2 Ver. 2 or Ver. 1 6-15 Protocol.
  • Page 260 M-Packet Determines whether or not the MFJ TNC deletes a 6-63 message after it has been forwarded. KISS ON|OFF Packet Allows the MFJ TNC to works as a modem for 6-64 special programs such as TCP/IP. LCALLS call none Packet...
  • Page 261 Determines whether the lower or upper case 6-66 characters are set. LFADD ON|OFF packet Enables the MFJ TNC to go to the next line when a 6-66 <CR> character is received. LFIGNORE ON|OFF Packet Line feeds are ignored except in transparent mode.
  • Page 262 Invokes efficient key up technique in transmitted 6-125 packet to increase throughput. TXDELAY Packet Tells the MFJ TNC how long to wait after keying 6-127 up the transmitter before sending data. TXDELAYC Packet Controls a new timer that runs after the regular...
  • Page 263 Commands Parameters Default Mode Function Page TXUIFRAME ON|OFF Packet Used to tell the MFJ TNC what to do with 6-130 the unconnected information left in its buffer. UNPROTO call1 Packet Sets the digipeat and destination address 6-130 fields of packets sent in the unconnected mode.
  • Page 264 MFJ-1270C/1274C MANUAL INDEX Chapter 16 Page 29...

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