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- Page 1 Digital488 IEEE 488 to Digital Interface INSTRUCTION MANUAL IOtech, Inc. • 25971 Cannon Road • Cleveland, Ohio 44146 • (440) 439-4091...
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Page 2: Warranty Information
Copyright, Trademark, and Licensing Notice All IOtech documentation, software, and hardware are copyright with all rights reserved. No part of this product may be copied, reproduced or transmitted by any mechanical, photographic, electronic, or other method without IOtech’s prior written consent. IOtech product names are trademarked; other product names, as applicable, are trademarks of their respective holders. - Page 3 Digital488 Digital488OEM Instruction Manual 110-0920 Revision 4.2 November 1990 IOtech, Inc 25971 Cannon Road Cleveland, Ohio 44146 (440) 439-4091...
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Page 5: Table Of Contents
Table of Contents Section1 Introduction Page General Description Available Accessories1.2 Specifications Abbreviations Section 2 Getting Started Page Inspection Configuration 2.2.1 IEEE Address Selection 2.2.2 IEEE Bus Output Terminator Selection 2.3 Digital Input/Output Ports 2.3.1 Logic Levels 2.3.2 Digital I/O Port Pin Outs 2.3.3 Control Lines 2.3.3.1... - Page 6 Table of Contents Section 3 Command Descriptions Page Configure (Cn) Data (D...Z) Data Ready (Rn) End or Identify (Kn) Execute (X) 3.10 Format (Fn) 3.11 Handshake (Hn) 3.18 Inhibit (Qn) 3.19 Invert (In) 3.20 Port (Pn) 3.21 Service Request Mask (Mn) 3.22 Serial Poll Status Byte 3.24...
- Page 7 Parallel Poll 4.11 Section 5 Service Information Page Factory Service Theory of Operation Digital488 Mother Board Component Layout 5.3 Digital488 I/O Board Component Layout Digital488OEM Component Layout Digital488 Parts List Digital488OEM Parts List Appendix A Digital488 Command Summary Appendix B...
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Page 9: Section1
Introduction 1.1 General Description The Digital488 is a digital input and output interface to the IEEE 488 bus. Each unit has 40 TTL level digital I/O lines, which are divided into 5 eight-bit ports. Each port is software programmable as input or output. The Digital488OEM is a board level interface with the same capabilities as the Digital488. -
Page 10: Available Accessories1.2
Section 1 Introduction 1.2 Available Accessories Additional accessories that can be ordered for the Digital488 include: CA-7-1 1.5 foot IEEE 488 Cable CA-7-2 6 foot IEEE 488 Cable CA-7-3 6 foot shielded IEEE 488 Cable CA-7-4 6 foot reverse entry IEEE 488 Cable CA-8-50†... -
Page 11: Specifications
Section 1 Introduction 1.3 Specifications Digital488 Specifications Digital I/O Terminal Installation Category: Standard: Not Applicable. CE: Category 1. Transistor-Transistor Logic (TTL) Levels: Outputs will drive 2 TTL loads. Connector: One 50-pin card edge (mating connector supplied). IEEE 488 &$87,21 The IEEE 488 terminal must only be used to control a non-isolated IEEE 488 system. - Page 12 Do not use this interface outdoors! The interface is intended for indoor use only! Outdoor conditions could result in equipment failure, bodily injury, or death! &$87,21 Do not connect AC power line directly to the Digital488. Direct AC connection will damage equipment. 1.3b...
- Page 13 Section 1 Introduction Digital488/OEM Specifications :$51,1* Do not use this interface outdoors! The interface is intended for indoor use only! Outdoor conditions could result in equipment failure, bodily injury, or death! &$87,21 Never disassemble the interface case while it is connected to the AC power line!
- Page 14 Section 1 Introduction General Configuration: Five 8-bit ports, programmable as inputs or outputs. Also included are programmable handshake lines, data latching capability, Clear and Trigger outputs, and a Service Request (SRQ) input. Dimensions: 205 mm deep x 115 mm wide x 28 mm high (8" x 4.5" x 1.1"). Weight: 0.23 kg.
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Page 15: Abbreviations
Section 1 Introduction 1.4 Abbreviations The following IEEE 488 abbreviations are used throughout this manual. addr n IEEE bus address "n" Attention line Controller Active Carriage Return data Data String Device Clear Group Execute Trigger Go To Local Listener Active Listen Address Group Line Feed Local Lock Out... -
Page 17: Getting Started
† Supplied with Digital488 Only and not the Digital488OEM 2.2 Configuration The Digital488 has one internal 8 position switch which determines the unit's IEEE address and its default IEEE bus output terminator. The switch is only read when the unit is powered on, and should only be set prior to applying power. The following figure illustrates the factory default setting for SW1. - Page 18 AC line and from the interface. Disconnect any IEEE or digital I/O cables prior to disassembly. WARNING Never open the Digital488 case while it is connected to the AC line. Failure to observe the warning may result in equipment failure, personal injury or death.
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Page 19: Ieee Bus Output Terminator Selection
Carriage Return - Line Feed with EOI asserted. The Digital488 ignores all terminators received from the bus controller. Only the Execute command (X) is used to signal the Digital488 that a command string has been completed. -
Page 20: Digital Input/Output Ports
Getting Started 2.3 Digital Input/Output Ports The Digital488 has 40 data lines which can be programmed in groups of 8 as either input or output. At power on, all 40 bits are in the input mode. Each 8 bit group is one port, beginning with Port 1 as the least significant 8 bits, and Port 5 as the most significant 8 bits. - Page 21 Section 2 Getting Started Digital488OEM I/O Connector Pin Out Not Used External Data Ready (I) Common (GND) Inhibit (O) Data Strobe (O) Digital I/O Bits 1 thru 40 PC Board Edge Clear (O) +5 Volts = Input Trigger (O) [ 50 mA Max!] = Output Service (I) Not Used...
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Page 22: Control Lines
I/O COMMON (Gnd). 2.3.3 Control Lines Five control lines enable handshaking of digital I/O data transfer to the Digital488. They are automatically activated with the corresponding I/O activity and can also be independently activated with the Handshake (Hn) command. 2.3.3.1 Clear (Pin 41) -
Page 23: Data Strobe
Refer to the following diagram for timing relationships. When using the EDR line with the R1 command, data is not read when the Digital488 is addressed to talk as with R0. The Digital488 will only output data when the EDR line transitions. -
Page 24: Inhibit
[Fn] modes except high speed binary [F5]. In this mode, it is asserted for the first data read after the Digital488 is addressed to talk. On the last data byte transfer, the data is read again with Inhibit asserted in anticipation of another data transfer. -
Page 25: Trigger
The Digital488 implements many of the capabilities defined by the IEEE 488 1978 specification. These are discussed in the following sections. Those bus uniline and multiline commands that the Digital488 does not support or respond to include: Remote Enable (REN) -
Page 26: My Talk Address (Mta)
If Inhibit is used to sequence external hardware, this line will pulse N+1 times; where N is the number of total (5 byte) data transfers. In this format the Digital488 does not have to be re-addressed to talk to read the ports multiple times. -
Page 27: My Listen Address (Mla)
In the high speed binary format (F5), the command interpreter is disabled. The Digital488 treats all bytes received as data to be output to the Digital I/O ports. Each time it receives five bytes or detects EOI it pulses the Data Strobe for approximately 15 microseconds. -
Page 28: Interface Clear (Ifc)
When the serial poll byte is accepted by the controller, any pending SRQs are cleared. The Digital488 will continue to try to output its serial poll response until it is serial poll disabled by the controller. -
Page 29: Installation
RAM self check. At the end of this self check all indicators should turn off except POWER. If you obtain the above response then your Digital488 is alive and well. If all LEDs remain on, then a ROM error has occurred. If all LEDs continue to flash (except the power LED), then a RAM error has occurred. -
Page 31: Command Descriptions
Examples are given for many of the commands using a Hewlett-Packard 85 computer in the immediate mode. It is implied that each command is terminated by the 'END LINE' key on the HP-85 in order to execute the command. The Digital488 bus address should be set to 18 for all examples. -
Page 32: Bit Set (An)
Configure command to be valid. The Strobe output line is not pulsed when the Bit Set command is sent. Bit n (1 thru 40) is set to logic one Example: reset the Digital488 CLEAR 718 configure all ports as output OUTPUT 718;"C5X"... -
Page 33: Bit Clear (Bn)
Configure command in order to be valid. The Strobe output line is not pulsed when the Bit Clear command is sent. Bit n (1 thru 40) is cleared to a logic 0 Example: reset the Digital488 CLEAR 718 configure all ports as output OUTPUT 718;"C5X"... -
Page 34: Bus Input/Output (Gn)
Bus Input/Output The Bus Output command determines whether input port data, output port data or both will be transmitted on the bus when the Digital488 is addressed to talk. The amount of data sent is dependent on the Pn command. -
Page 35: Configure Cn
Mode n (0 thru 5) defines which ports are input and output Port in = programmed as an input port out = programmed as an output port Example: reset the Digital488 CLEAR 718 select port 1 as output, ports 2 thru 5 OUTPUT 718;"C1X" as inputs... -
Page 36: Data (D
55 to port 1 read data from port 1 ENTER 718; A$ DISP A$ display shows 55 select all ports OUTPUT 718;"P0X" send data to all 40 bits OUTPUT 718;"D1234567890ZX" ENTER 718;A$ read data from the Digital488 display shows 1234567890 DISP A$... - Page 37 Section 3 Command Descriptions send 12 bits of data to the least significant bits OUTPUT 718;"D123ZX" ENTER 718; A$ read data from the Digital488 display shows 0000000123 DISP A$ set port 5 only OUTPUT 718;"P5D21ZX" select all ports OUTPUT 718;"P0X"...
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Page 38: Data Ready (Rn)
In the default mode (R0) data is read when the Digital488 is addressed to talk. In the R1 mode, it will wait for the selected External Data Ready (EDR) transition before reading the data and formatting it for output. -
Page 39: End Or Identify (Kn)
EOI mode by programming the Digital488 from the bus. In the K0 mode, the EOI line is asserted by the Digital488 on the last byte of every bus output string. In the K1 mode the EOI function is disabled (except when using the binary modes [F4 and F5] ). -
Page 40: Execute (X)
Command Descriptions Execute Commands sent to the Digital488 will result in no action until the unit is instructed to execute these commands. This is done by sending an X, usually as the last character of a command string. Commands sent without an X are stored in the internal buffer until an X is received. -
Page 41: Format Fn
If the data sent is greater than the number of bits programmed for output or selected by the Pn command, the Digital488 will generate a conflict error and ignore the entire command string. The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the selected port(s). - Page 42 If the data sent is greater than the number of bits programmed for output or selected by the Pn command, the Digital488 will generate a conflict error and ignore the entire command string.
- Page 43 The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the selected port(s). When the Digital488 is addressed to talk (R0) it asserts Inhibit, reads the data from all ports, unasserts Inhibit and outputs the number of characters determined by the Gn and Pn commands.
- Page 44 Gn and Pn commands. Leading zeros are not suppressed and the bus terminators are appended to the output. After output the Digital488 must be re-addressed to talk to perform subsequent reads. EDR (R1) may also be used to capture data in this format.
- Page 45 If the data sent is greater than the number of bits programmed for output or selected by the Pn command, the Digital488 will generate a conflict error and ignore the entire command string. The Data Strobe output is pulse for approximately 50 microseconds after new data is output on the selected port(s).
- Page 46 In the F5 high speed binary format, the command interpreter is disabled. When addressed to listen, the Digital488 treats all bytes received as data to be output to the Digital I/O ports. Each time it receives five bytes or detects EOI asserted, it pulses the Data Strobe for approximately 15 microseconds.
- Page 47 Section 3 Command Descriptions The only programmable method to exit the F5 high speed binary format is device clear (DCL) or Selected Device Clear (SDC). When received, it enables the command interpreter and changes the format to F0. All other parameters remain unchanged. In addition, the Clear output line is not pulsed by DCL or SDC when the interface is in F5.
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Page 48: Handshake Hn
Handshake The Handshake control command enables software control of the handshake lines, independent of any other I/O operations. When the Digital488 receives an Hn command, the respective handshake line is pulsed for approximately 50 microseconds. It returns to its steady- state condition after pulsing. -
Page 49: Inhibit (Qn)
I/O activities. The 'set' and 'clear' levels of the Inhibit line are determined by the Invert command. Clear the Inhibit line (return to unasserted state) Set the Inhibit line (place in the asserted state) Example: reset the Digital488 CLEAR 718 set the Inhibit line OUTPUT 718;"Q1X" 3.19... -
Page 50: Invert (In)
Data Strobe output is active low Clear output is active low Data is low true EDR input is falling-edge sensitive Service input is falling-edge sensitive Example: reset the Digital488 CLEAR 718 select EDR and Service input as OUTPUT 718;"I32XI64X" falling-edge sensitive Note: performs the same function as above OUTPUT 718;"I96X"... -
Page 51: Port Pn
It is recommend that the Bus Output command be used with the PO mode to determine which ports will be output when the Digital488 is addressed to talk. Data in modes P1 throuth P5 will be input or output in groups of eight bits. -
Page 52: Service Request Mask (Mn)
Command Descriptions Service Request Mask (SRQ) The Service Request (SRQ) mode is used by the Digital488 to alert the controller to one of several conditions described below. Multiple SRQ conditions can be enabled simultaneously by issuing them sepatately or by combining them in one command. - Page 53 M8 will generate a Service Request when the Digital488 self-test fails. Refer to the Test command (T0) description for details on self-tests. M16 will generate a Service Request when the Digital488 has completed the execution of a set of commands from the bus controller. This is used by the controller to assure the completion of a set of commands before sending a subsequent set of commands.
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Page 54: Serial Poll Status Byte
The status of DIO4 is determined after the Test command (T0X) is sent to the Digital488. If the self test passes, the DIO4 bit will remain a zero. If the self test fails, DIO4 will be set to a logic 1. - Page 55 ERROR and SRQ LEDs should illuminate display should be 84 (64+16+4) SPOLL (718) 64 denotes the Digital488 was the source of the SRQ. 16 denotes the Digital488 is READY for more commands. 4 denotes a Bus error. When serial polled,the SRQ LED will turn off.
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Page 56: Status Un
Send the Digital488 status when next addressed to talk Send the status of bit n (1 thru 40) when next addressed to talk The format of the status byte returned by the Digital488 after receiving a U0 command is as follows: *.*C#E#F#G#I###K#M###P#R#Y#... - Page 57 Section 3 Command Descriptions Below is a summary of the Status (U0) information. Configuration All ports are inputs Port 1 is an output, ports 2 thru 5 are inputs Ports 1 and 2 are outputs, ports 3 thru 5 are inputs Ports 1 thru 3 are outputs, ports 4 and 5 are inputs Ports 1 thru 4 are outputs, port 5 is an input All ports are outputs...
- Page 58 Section 3 Command Descriptions End Or Identify EOI enabled EOI disabled Service Request SRQ is disabled SRQ on Service input transition SRQ on EDR input transition SRQ on Bus error SRQ on Test error SRQ on Ready Note: the status indication reflects the sum of all received Service Request commands. Selected Port All ports selected Port 1 selected...
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Page 59: Terminator Yn
Section 3 Command Descriptions Terminator The IEEE 488 bus terminator defaults at power-on to the settings on Switch S1 It also may be programmed for any combination of Carriage Return (CR) and Line Feed (LF). The Y0 mode is the most commonly accepted terminator, CR-LF. Y1 reverses the sequence to send LF-CR. -
Page 60: Test (T0)
The Test command is used to verify hardware and LED operation. Perform RAM and ROM test The T0 command will cause the Digital488 to initiate a ROM/RAM test. If the test is successful, all LEDs will flash for one-half second. If a test fails, the Error LED will remain illuminated. -
Page 61: Ieee 488 Primer
4.1 HISTORY The IEEE 488 bus is an instrumentation communication bus adopted by the Institute of Electrical and Electronic Engineers in 1975 and revised in 1978. The Digital488 conforms to this most recent revision designated IEEE 488-1978. Prior to the adoption of this standard, most instrumentation manufacturers offered their own versions of computer interfaces. - Page 62 Section 4 IEEE 488 Primer At a committee meeting, everyone present usually listens. This is not the case with the GPIB. The Active Controller selects which devices will listen and commands all other devices to ignore what is being transmitted. A device is instructed to listen by being Addressed to Listen.
- Page 63 Section 4 IEEE 488 Primer...
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Page 64: Send It To My Address
Section 4 IEEE 488 Primer 4.3 SEND IT TO MY ADDRESS In the previous discussion, the terms Addressed to Talk and Addressed to Listen were used. These terms require some clarification. The IEEE 488 standard permits up to 15 devices to be configured within one system. -
Page 65: Interface Clear (Ifc)
Section 4 IEEE 488 Primer 4.4.2 Interface Clear (IFC) The IFC line is used only by the System Controller. It is used to place all bus devices in a known state. Although device configurations vary, the IFC command usually places the devices in the Talk and Listen Idle states (neither Active Talker nor Active Listener). -
Page 66: Handshake Lines
Section 4 IEEE 488 Primer 4.5 HANDSHAKE LINES The GPIB uses three handshake lines in an "I'm ready - Here's the data - I've got it" sequence. This handshake protocol assures reliable data transfer, at the rate determined by the slowest Listener. One line is controlled by the Talker, while the other two are shared by all Active Listeners. -
Page 67: Data Lines
Section 4 IEEE 488 Primer 4.6 DATA LINES The GPIB provides eight data lines for a bit parallel/byte serial data transfer. These eight data lines use the convention of DIO1 through DIO8 instead of the binary designation of D0 to D7. The data lines are bidirectional and are active low. 4.7 MULTILINE COMMANDS Multiline (bus) commands are sent by the Active Controller over the data bus with ATN asserted. -
Page 68: Listen Address Group (Lag)
Section 4 IEEE 488 Primer 4.7.2 Listen Address Group (LAG) There are 31 (0 to 30) listen addresses associated with this group. The 3 most significant bits of the data bus are set to 001 while the 5 least significant bits are the address of the device being told to listen. -
Page 69: Selected Device Clear (Sdc)
Section 4 IEEE 488 Primer 4.7.8 Selected Device Clear (SDC) This causes a single device to be initialized to a pre-defined or power up state. ($04) 4.7.9 Serial Poll Disable (SPD) The SPD command disables all devices from sending their Serial Poll status byte. -
Page 70: Parallel Poll Configure (Ppc)
Section 4 IEEE 488 Primer 4.7.14 Parallel Poll Configure (PPC) This configures devices capable of performing a Parallel Poll as to which data bit they are to assert in response to a Parallel Poll. ($05) 4.7.15 Parallel Poll Unconfigure (PPU) This disables all devices from responding to a Parallel Poll. -
Page 71: Serial Poll
Section 4 IEEE 488 Primer 4.8.1 Serial Poll Suppose the Controller receives a service request. For this example, let's assume there are several devices which could assert SRQ. The Controller issues an SPE (Serial Poll enable) command to each device sequentially. -
Page 73: Service Information
5.2 Theory of Operation The Heart of the Digital488 is a 6809 microprocessor [U101] supported by 8K bytes of firmware EPROM [U102 (2764)] and 8K bytes of static RAM [U103 (6264)]. A Versatile Interface Adapter [U104 (65B22)] is used to generate real-time interrupts for the firmware operating system. -
Page 77: Digital488 Parts List
Section 5 Service Information 5.6 Digital488 Replaceable Parts List Schematic Part Number Description C101-C108 C-5-.1 Ceramic, 25v C110,C113 C-5-.1 Ceramic, 25v C117,C118 C-5-15p Ceramic, 25v C124 C-2-10 Electrolytic, 25v C201-C205 C-5-.1 Ceramic, 25v C123 C-5-1 Ceramic, 25v D101 RF-1 Small Signal Diode... - Page 78 R103 RN-2-470 470½ x 5 SIP S101 SW-6-8 8 Pole DIP U101 IC-1 MC68B09P Microprocessor U102 Digital488-600 Programmed EPROM U103 IC-41 6264-15 8K x 8 CMOS SRAM U104 IC-23 65B22 Versitile Interface Adapter U105 Digital488-601 Programming Equation - 16L8 PAL...
- Page 79 Appendix A Digital488 Command Summary Command Code Description Bit Set Set bit n (1 thru 40) Bit Clear Clear bit n (1 thru 40) Bus Output Input and Output port data sent on talk Only Input port data sent on talk...
- Page 80 Appendix A Digital488 Command Summary Command Code Description Inhibit Clear Inhibit line Set Inhibit line Invert All control line outputs are active high Inhibit output is active low Trigger output is active low Data Strobe output is active low Clear output is active low...
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