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Allen-Bradley 1779-KFMR User Manual

Data highway ii synchronous-device interface
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Allen Bradley

User Manual

Data Highway II
Synchronous-
Device Interface
(Cat. No. 1779-KFM,
KFMR)

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Summary of Contents for Allen-Bradley 1779-KFMR

  • Page 1: User Manual

    Allen Bradley User Manual Data Highway II Synchronous- Device Interface (Cat. No. 1779-KFM, KFMR)

  • Page 2: Table Of Contents

    Table of Contents Using This Manual ....... Manual's Purpose ........Audience .
  • Page 3 Table of Contents Installing the 1779 KFM Interface ....Chapter Objectives ........Planning the Layout .
  • Page 4 Table of Contents Data Highway Message Set ......Chapter Objectives ........Selecting Data Highway Messages .
  • Page 5 Table of Contents Status Codes ........What This Appendix Contains .

  • Page 6: Using This Manual

    Manual's Purpose This manual tells you about the Synchronous-Device/DHII Interface (Cat. No. 1779-KFM) and the Redundant Synchronous-Device/DHII Interface (Cat. No. 1779-KFMR). This manual tells you how to install and use a 1779-KFM interface in a Data Highway II communication network.

  • Page 7: Manual Organization

    Chapter 1 Using This Manual Manual Organization This manual is organized into the following chapters: Chapter Title What's Covered Using This Manual The manual's purpose, its audience, its vocabulary, and its organization. Introducing the 1779 KFM Interface An overview of the 1779 KFM interface, its function, its application, and the messages that it is capable of sending and receiving.

  • Page 8: Introducing The 1779 Kfm Interface

    One Power-Supply Board (Cat. No. 1779-PH2) One Host Board (Cat. No. 1779-JFM) One Media Access Control Board (Cat. No. 1779-JMA) A redundant 1779-KFMR interface has a Redundant Media Access Control Board (Cat. No. 1779-JMAR) instead of a Media Access Control board.
  • Page 9 Chapter 2 Introducing the 1779 KFM Interface Figure 2.1 1779 KFM Interface with Removable Frame Separated from Stationary Frame Stationary Frame Removable Frame...

  • Page 10: What Is Its Function

    Chapter 2 Introducing the 1779 KFM Interface Figure 2.2 Rear View of the Removable Frame Assembly Shield Power Supply Host Board Board Board 12617 What Is Its Function? The 1779-KFM interface functions as a communication interface between a synchronous RS-422/449 compatible intelligent device (host device) and other nodes of a Data Highway II link (Figure 2.3).

  • Page 11: Compatible Host Devices

    The DATA HWY II jack provides dropline cable connection to a tap on a Data Highway II link. A redundant 1779-KFMR interface has a second DATA HWY II jack for a redundant set of cabling for the link. Your Data Highway II cable redundant interface module (Cat.
  • Page 12 AC POWER ON User-Supplied ACCESS Cable AC POWER SLOW BLOW FUSE 2A, 250V EXTENDED RS-449 115V AC/230V AC CHANNEL Host CONFIG INTERNALLY SWITCH Computer SELECTABLE DATA HWY II PORT L2/N DATA HWY II PORT CAT. NO. 1779-KFMR DHII MEDIUM-SPEED COMPUTER INTERFACE...

  • Page 13: Node Interfaces

    Asynchronous-Device/DHII Interface (Cat. No. 1779-KFL) Redundant Asynchronous-Device/DHII Interface (Cat. No. 1779-KFLR) Synchronous-Device/DHII Interface (Cat. No. 1779-KFM) Redundant Synchronous-Device/DHII Interface (Cat. No. 1779-KFMR) PLC-2/DHII Interface (Cat. No. 1779-KP2) Redundant PLC-2/DHII Interface (Cat. No. 1779-KP2R) PLC-3/DHII Interface (Cat. No. 1779-KP3) Redundant PLC-3/DHII Interface (Cat. No. 1779-KP3R)
  • Page 14 Chapter 2 Introducing the 1779 KFM Interface In each case, the device is the host for the interface. A host device is a node on one end of its host/interface link, and its interface to the Data Highway II link is a node on the other end of the host/interface link. However, to the other nodes of the Data Highway II link, the host device and its interface, combined, are accessed as a single node of the Data Highway II link.
  • Page 15 Chapter 2 Introducing the 1779 KFM Interface Programming The program in a host device at one node can initiate a transfer of a message to or from any other node in the network. Programming a host computer for communication through a 1779-KFM interface is described in later chapters.
  • Page 16 (local tap or extended tap). For example, with RG-11-type coaxial cable approved by Allen-Bradley, local taps, and 52 nodes in a link, the trunkline length can be up to 4,100 cable-feet.

  • Page 17: Media Access Method

    Chapter 2 Introducing the 1779 KFM Interface Media Access Method Because the Data Highway II link has a carrier-band bus medium, only one node can transmit at a time. However, each node in a Data Highway II link has a regularly scheduled opportunity to access the medium to transmit messages to other nodes.

  • Page 18: Command/Reply

    Chapter 2 Introducing the 1779 KFM Interface Command/Reply Communication is always initiated by a node transmitting a command message. Only the node holding the token can initiate communication by transmitting a command message. When a node transmits a command to read an immediate-access block, the node receiving the command immediately transmits a reply message while the initiating node still holds the token.
  • Page 19 Chapter 2 Introducing the 1779 KFM Interface If the local node transmits a command to write with no reply, the remote node never transmits a reply (Figure 2.6). If the local node transmits a command to write with reply, when the remote node interface receives the token, it transmits a reply message to indicate whether it was able to successfully write into the host’s memory (Figure 2.7).
  • Page 20 Chapter 2 Introducing the 1779 KFM Interface node. The local node interface then verifies that the data it received is identical to what it had transmitted (Figure 2.8). Figure 2.8 Write Verified Message Transfer Command Message - Block of data to write into host at Node 2 Node Node...

  • Page 21: Message Priority

    Chapter 2 Introducing the 1779 KFM Interface Message Priority The two categories of message priority are: Supervisory Time-Critical (Time-critical commands are a subset of supervisory commands.) A write verified command always has supervisory priority. A command to read an immediate-access block always has time-critical priority. For each of the other types of commands, you can specify them to have either time-critical priority or supervisory priority.

  • Page 22: Message Sets Available

    Chapter 2 Introducing the 1779 KFM Interface Message Sets Available On a Data Highway II network, with a synchronous-device/DHII interface, you can communicate with other nodes through messages of the following message sets: Data Highway Time-Critical Remote Command Control Packet Assembler/Disassembler (PAD) Station Management In Chapter 7, we provide a comparison of these various message sets.

  • Page 23: Summary

    Chapter 2 Introducing the 1779 KFM Interface Figure 2.9 Redundant Cabling Configuration for a Data Highway II Link Trunkline Cabling System A Trunkline Dropline Dropline Redundant Redundant Redundant Node Node Node Interface Interface Interface Dropline Dropline Trunkline Cabling System B Trunkline Summary Now that you have been introduced to the 1779-KFM interface and...

  • Page 24: Installing Cabling Hardware For The Data Highway Ii Link

    Chapter Installing Cabling Hardware for the Data Highway II Link Chapter Objectives This chapter explains how to install cabling hardware for a Data Highway II link and contains information on: Identifying the Hardware Planning the Cabling Configuration Installing Taps Installing the Trunkline Installing Droplines Identifying the Hardware To install a Data Highway II link, you will need the following cabling...

  • Page 25: Coaxial Cable

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Coaxial Cable The coaxial cable for the trunkline has both a foil and a braided wire outer conductor (Figure 3.1). Figure 3.1 Coaxial Cable Braid Foil Inner Conductor Insulation Insulating Jacket...
  • Page 26 Chapter 3 Installing Cabling Hardware for the Data Highway II Link Local Tap Each node on a Data Highway II link requires a local tap. Each local tap has two trunkline jacks, a dropline jack, and a cap for covering the dropline jack when you do not have a dropline connected.

  • Page 27: Crimping Tool

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Crimping Tool You will need the crimping tool for fastening the cable plugs to the trunkline cable segments (Figure 3.3). Figure 3.3 Crimping Tool Terminator At each end of the trunkline, you connect a terminator to the unused trunkline jack on a tap (Figure 3.4).

  • Page 28: Planning Your Cabling Configuration

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Planning Your Cabling Before installing any hardware, carefully plan your cabling configuration. Configuration The general cabling configuration of a Data Highway II link is shown in Figure 3.5. Figure 3.5 Cabling Configuration for a Data Highway II Link Trunkline Terminator...
  • Page 29 Chapter 3 Installing Cabling Hardware for the Data Highway II Link You can calculate the length limit (in cable-feet) for the trunkline cable with the formula: Trunkline Length = 8,000 - (No. of Local Taps x 75) For example, if your link requires 24 taps, the trunkline length is limited to 6,200 cable-feet.
  • Page 30 Chapter 3 Installing Cabling Hardware for the Data Highway II Link Figure 3.7 Minimum Bend Radius for Trunkline (6 Inches) 6 inch Plan your dropline cable routing so that the cable will have no sharper bend than a minimum 3-inch bend radius (Figure 3.8). Figure 3.8 Minimum Bend Radius for Dropline (3 Inches) 3 inch...
  • Page 31 Chapter 3 Installing Cabling Hardware for the Data Highway II Link Figure 3.9 Local Tap Mounting Dimensions Use No. 5 Mounting Bolts (2 Places) 2.1 in. (54 mm) 1.5 in. (38 mm) 1.0 in. (25 mm) 3.1 in. (79 mm) 0.2 in.
  • Page 32 Chapter 3 Installing Cabling Hardware for the Data Highway II Link Figure 3.10 Local Tap Mounted Below a Node Interface Node Trunkline Interface Use conduit for the first 20 feet from enclosure. Enclosure Wall Dropline Figure 3.11 shows an example of taps mounted beside a node interface. The trunkline cables run straight out through the top of the enclosure.

  • Page 33: Installing Taps

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Planning Cable Routing Follow these cable routing recommendations for protecting the coaxial cable from electrical interference: If the cable must cross power feed lines, it should do so only at right angles.

  • Page 34: Cutting The Cable

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Figure 3.12 Local Tap with Cap on Dropline Jack Put cap on dropline jack. Installing the Trunkline Because the trunkline can vary greatly from one Data Highway II configuration to the next, you have to construct your own trunkline. The trunkline actually consists of a number of cable segments.

  • Page 35: Attaching The Plugs

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Attaching the Plugs After cutting the cable segments to the desired lengths, attach a plug to each end of each segment. Figure 3.13 illustrates the steps given here for attaching the plugs: Slide the plug sleeve over the end of the cable segment.
  • Page 36 Chapter 3 Installing Cabling Hardware for the Data Highway II Link Figure 3.13 Attaching a Plug to a Trunkline Segment 0.7 in. Coaxial Cable 0.3 in. 0.2 in. Steps 1 through 4 Plug Sleeve Plug Pin Steps 5 and 6 Braid Steps 7 and 8 Plug Body...

  • Page 37: Plugging Into The Tap

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Plugging into the Tap At the tap at each of the two physical ends of the link, plug the trunkline segment into one trunkline jack of the tap. Plug a terminator into the other trunkline jack of the tap (Figure 3.14).

  • Page 38: Installing Droplines

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Figure 3.15 Connecting Trunkline Segments to a Local Tap Trunkline Trunkline Segment Segment Dropline To guard against the minimum bend radius being violated or a cable being pulled out of its plug, secure each cable in place with some form of strain-relief device.

  • Page 39: Chapter Summary

    Chapter 3 Installing Cabling Hardware for the Data Highway II Link Figure 3.16 Connecting a Dropline to the KFM Node Interface Cap and chain must not touch a conductive surface. Dropline Hardware Manufacturers' Here are the addresses and phone numbers of the manufacturers listed in Addresses and Phone Numbers “Identifying the Hardware”: Alpha Wire Corporation...

  • Page 40: Installing The 1779 Kfm Interface

    Chapter Installing the 1779 KFM Interface Chapter Objectives This chapter presents procedures for: Planning the Layout Mounting the 1779-KFM Interface Setting Switches Connecting Communication Cables Connecting Power and Ground Planning the Layout The maximum distance between components is limited by cable length. You must plan the layout so that the 1779-KFM interface is within 4,000 cable-feet of the host computer.
  • Page 41 Chapter 4 Installing the 1779 KFM Interface To allow necessary air flow for cooling of components, refer to Figure 4.1 and follow these rules: Do not mount an I/O chassis above a processor chassis. Minimum vertical separation between chassis and to top and bottom of the enclosure is six inches, with no chassis mounted above the 60 C air temperature level (Figure 4.1).

  • Page 42: Mounting The 1779 Kfm Interface 4

    EXTENDED RS-449 115V AC/230V AC CHANNEL CONFIG INTERNALLY SWITCH SELECTABLE DATA HWY II PORT L2/N DATA HWY II PORT CAT. NO. 1779-KFMR DHII MEDIUM-SPEED COMPUTER INTERFACE 6.5 in. (165 mm) Clearance depth including cable connectors is 11 inches (28 cm).

  • Page 43: Setting Link Address

    Chapter 4 Installing the 1779 KFM Interface Setting Link Address On the front of the 1779-KFM interface is a set of three link-address thumbwheel switches (Figure 4.3). Set these switches to designate the link address of the node. The top switch represents the most-significant digit (MSD).
  • Page 44 Chapter 4 Installing the 1779 KFM Interface The switches are in three switch assemblies. In this publication, we show and describe switches as being ON or OFF. Printed on the actual switch assemblies are the words ON and OFF or the word OPEN. OPEN corresponds to OFF.
  • Page 45 Chapter 4 Installing the 1779 KFM Interface Figure 4.4 Host Board Switches 1779 KFM/KFMR LEGEND Option Enabled Option Disabled White Is Depressed MODE SUPERVISORY NATIVE PROTOCOL Reserved Reserved Execute Diagnostic Commands Reserved Reserved PRIVILEGE OPTIONS Reserved Reserved Reserved Initiate Network Parameter Changes Reserved PROTECTION OPTIONS Accepts Network Parameter Changes...
  • Page 46 Chapter 4 Installing the 1779 KFM Interface Execute Diagnostic Commands When the 1779-KFM interface receives a diagnostic command from its host device, it transmits the command over the Data Highway II link to the destination station. However, when the interface receives a diagnostic command from a remote node of the Data Highway II link, its actions are conditioned by the setting of the diagnostic commands switch.

  • Page 47: Setting Mac Board Switches

    Chapter 4 Installing the 1779 KFM Interface Data Transmission Rate Set the data transmission rate switches to select the data transmission rate on the RS-422/499 link to the host device. Set These To Select This Data Transmission Rate (in Bits/s) Switches 9.6K 19.2K...
  • Page 48 Chapter 4 Installing the 1779 KFM Interface While holding the removable frame at the top and bottom, lift it up an inch and then out away from the stationary frame. Locate the switches at the rear edge of the MAC board (middle board) between the bottom two ribbon cables (Figure 4.6).

  • Page 49: Connecting Communication Cables 4

    Chapter 4 Installing the 1779 KFM Interface Connecting Communication After you have set the host-board switches to select the type of operation Cables you want, you can begin connecting the communication cables necessary for your application. You must connect the cable from the interface to the host device before power up to prevent a fault condition.
  • Page 50 ACCESS User-Supplied Cable AC POWER SLOW BLOW FUSE 2A, 250V EXTENDED RS-449 115V AC/230V AC CHANNEL CONFIG INTERNALLY Host SWITCH SELECTABLE Computer DATA HWY II PORT L2/N DATA HWY II PORT CAT. NO. 1779-KFMR DHII MEDIUM-SPEED COMPUTER INTERFACE 4 11...
  • Page 51 Chapter 4 Installing the 1779 KFM Interface Figure 4.8 Wiring Diagram for the Cable to the Host Device RS 449 Connector of RS 449 Connector of 1779 KFM Interface (DCE) Host Device (DTE) Shield Do Not Connect To Tap Pull the removable frame out to the switch-setting position before connecting to the tap.
  • Page 52 AC POWER ON ACCESS AC POWER SLOW BLOW FUSE 2A, 250V EXTENDED RS-449 115V AC/230V AC CHANNEL CONFIG INTERNALLY Host SWITCH SELECTABLE Computer DATA HWY II PORT L2/N DATA HWY II PORT CAT. NO. 1779-KFMR DHII MEDIUM-SPEED COMPUTER INTERFACE Dropline 4 13...

  • Page 53: Connecting Power And Ground

    Chapter 4 Installing the 1779 KFM Interface Connecting Power and Ground To connect the 1779-KFM interface to power and ground, follow these steps: Pull the removable frame out to the switch-setting position. This exposes the power-selection switch on the right side of the removable frame assembly (Figure 4.10).
  • Page 54 Chapter 4 Installing the 1779 KFM Interface Connect the GND post on the removable frame to the central ground bus. The central ground bus must connect to the grounding electrode system through a grounding electrode conductor. The interface is shipped to you with a wire connecting the post to the stationary frame and another wire connecting the post to the GND terminal of the terminal block.

  • Page 55: Power Distribution

    The power consumed by the 1779-KFM interface is 50W. Multiply the power requirements of the Allen-Bradley power supplies by 2.5 and add all other power requirements (input circuits, output circuits) to determine the required rating of the transformer. The power requirements must take into consideration the surge currents of devices controlled by the controller.

  • Page 56: Summary

    85 volts. The power supply will sense this as a low voltage and shut down the interface prematurely. Allen-Bradley power supplies have circuits which suppress electromagnetic interference from other equipment. For installations near particularly bad electrical noise generators, an isolation transformer can provide further suppression of electromagnetic interference from other equipment.

  • Page 57: Operation And Troubleshooting

    Indicators The 1779-KFM interface has 21 LED indicators on its front panel. The 1779-KFMR interface has the same indicators plus the redundant-warning indicator and the port-ready, signal-quality, and tap-fail indicators for the redundant port. These indicators provide you with the following...
  • Page 58 DC POWER ON AC POWER ON DH II ACCESS AC POWER SLOW BLOW FUSE 2A, 250V EXTENDED RS-449 CHANNEL 115V AC/230V AC CONFIG INTERNALLY SWITCH SELECTABLE DATA HWY II PORT L2/N DATA HWY II PORT CAT. NO. 1779-KFMR DHII MEDIUM-SPEED COMPUTER INTERFACE...
  • Page 59 Chapter 5 Operation and Troubleshooting When This Indicator: Then: NODE PASS On Green The host and MAC boards performed and passed self diagnostic tests. HOST FAULT On Red The host board has either (1) failed the self diagnostic test or (2) faulted while in operation. NODE TEST On Yellow The host and MAC boards are performing self diagnostic tests.

  • Page 60: Operation Switches

    Chapter 5 Operation and Troubleshooting Operation Switches The interface has three switches on its front panel for you to use in operating the interface (Figure 5.1). AC POWER Switch EXIT REQUEST Switch TEST/RUN/RESET Switch AC Power Switch The AC POWER switch is a toggle switch. In the ON position, this switch connects power from the input power terminals, through the fuse, to the power-supply circuits.

  • Page 61: Operating The 1779 Kfm Interface

    Chapter 5 Operation and Troubleshooting In the RUN mode, the interface can communicate with other nodes of the Data Highway II link. When you power up the interface in RUN mode, it goes through a reset cycle and a 15-second self-diagnostic test cycle before seeking membership in a logical ring on the Data Highway II link.

  • Page 62: Replacing Boards

    Chapter 5 Operation and Troubleshooting transmitting HDLC flag sequences which are indicated by the TRANSMIT indicator turning on half-intensity yellow. Whenever you want to turn off interface power or switch out of RUN mode, press the EXIT REQUEST switch first. This exit request saves the other nodes time they would otherwise waste trying to pass the token to a node that they can’t find.
  • Page 63 Chapter 5 Operation and Troubleshooting Remove the AC power connections from L1 and L2/N and the ground connection from the GND post on the interface. Disconnect the green conductor that grounds the stationary frame to the ground post on the removable frame (Figure 5.2). Figure 5.2 Green Conductor Connecting the Stationary Frame to the Ground Post on the Removable Frame...
  • Page 64 Chapter 5 Operation and Troubleshooting Figure 5.3 Rear View of the Removable Frame Assembly Shield Ribbon Cables Power Supply Host Board Board Board 12617A 10. On the top two ribbon-cable connectors, locate the levers for locking and ejecting the connectors (Figure 5.4).
  • Page 65 Chapter 5 Operation and Troubleshooting Figure 5.4 Locking/Ejecting Levers on Connectors Levers 11. Push the levers apart with your thumbs to eject the cable from the connector on the board. 12. Remove all three ribbon cables. 13. Remove five screws to remove the power-supply board. 14.
  • Page 66 Chapter 5 Operation and Troubleshooting 16. With the screws removed, you can slide the faulted board straight out the back of the removable frame. 17. Replace the faulted board with a spare. 18. Replace the mounting screws. 19. Reconnect the three ribbon cables to the back of the boards. CAUTION: Do not misalign the pins when connecting the bottom ribbon cable (Figure 5.5).
  • Page 67 Chapter 5 Operation and Troubleshooting 20. Slide the removable frame back onto the stationary frame. 21. Tighten the four thumbscrews on the front of the interface. The thumbscrews must be tight to ensure that AC power is not interrupted by the interlock switch on the power-supply board. 22.

  • Page 68: Troubleshooting The Interface

    Chapter 5 Operation and Troubleshooting Troubleshooting the Interface When you suspect that the interface is not functioning properly, follow these steps (Figure 5.6). Figure 5.6 Troubleshooting Flowchart Problem Suspected Check: AC POWER Switch Fuse AC Power Source Interlock Switch Step 1 POWER Power-Supply Board Set the AC power switch to...

  • Page 69: Chapter Summary

    Chapter 5 Operation and Troubleshooting Check the AC POWER ON indicator. OFF — If off, check the AC POWER switch setting, fuse, AC source voltage, and interlock switch. If you still haven’t found the source of the problem, try replacing the power-supply board. ON —...

  • Page 70: Hdlc Data Link Layer

    Chapter HDLC Data Link Layer Chapter Objectives This chapter describes the HDLC frames, the fields within the frames, and the sequences of transmitting and receiving frames at the data-link layer for communication along the RS-422/449 link between the host computer and the 1779-KFM interface.

  • Page 71: Data Link Control Method

    Chapter 6 HDLC Data Link Layer Data Link Control Method We define the method of data-link control from several perspectives. On the RS-422/449 link, the computer and the 1779-KFM interface are combined stations that form a balanced configuration for two-way simultaneous operation.
  • Page 72 Chapter 6 HDLC Data Link Layer Physical Circuit AB carries command and response frames from A to B. Physical Circuit BA carries command and response frames from B and A. A frame often carries both a command and a response. Therefore, the transmitter is responsible for sending all frames.

  • Page 73: States And Modes

    Chapter 6 HDLC Data Link Layer Logical States and Modes The host computer and the 1779-KFM interface communicate with each other in three logical states: Data Transfer State (DTS) — While in the data transfer state, a node may transmit and receive data. In this state, the nodes are always in the asynchronous balanced mode (ABM).
  • Page 74 Chapter 6 HDLC Data Link Layer Where the fields of the frame are as follows: FLG is the flag sequence field (one byte). ADR is the RS-422/449 link address field (one byte). CTL is the control field (one byte). DATA is the data field (variable length). FCS is the frame check sequence field (two bytes).
  • Page 75 Chapter 6 HDLC Data Link Layer Address Field The address field contains the link-level address on the RS-422/449 link. The addresses of the two nodes on this link are: Address Node 1779 KFM Interface Computer The address in this field denotes the receiver on this link which is receiving and responding to a link-level command.
  • Page 76 Chapter 6 HDLC Data Link Layer Frame Check Sequence Field All frames include a 16-bit frame check sequence (FCS) field just prior to the closing flag. The FCS is also referred to as the cyclic redundancy code (CRC). The FCS provides a high level of data security. The FCS can detect: All Single-Bit and Double-Bit Errors All Errors of Odd Numbers of Bits...
  • Page 77 Chapter 6 HDLC Data Link Layer When the transmitting node sends five contiguous ones anywhere between the opening flag and the closing flag of a frame, it automatically inserts an extra zero bit. The insertion of the zero bit thus applies to the contents of the address, control, data, and FCS fields.
  • Page 78 Chapter 6 HDLC Data Link Layer Continuing with the example, consider a node receiving the following bit stream from across the link: 0101 11110 1001 1011 11101 11110 1011 11100 The previously inserted zeros would be deleted as follows: Zeros Deleted 0101 1111 1001...

  • Page 79: Control Field Formats 6

    Chapter 6 HDLC Data Link Layer The Address 3 would be: Time 1 1 0 0 0 0 0 0 In the control field, the order of bit transmission for sequence-number values and command/response codes is low bit first. In the FCS field, the order of bit transmission is high bit first. In the data field, the order of bit transmission is not determined by or relevant to the HDLC data-link layer.
  • Page 80 Chapter 6 HDLC Data Link Layer of data frames, and indicating temporary interruption of capability to receive data frames. The functions of N(R) and P/F are independent. Use the unnumbered format to provide additional link control functions. This format contains no sequence numbers; therefore, it has a 5-bit sub-field for a command/response code.

  • Page 81: States And Modes 6

    Chapter 6 HDLC Data Link Layer A node may be busy transmitting a long data frame while it is receiving a series of short data frames. After the node finishes transmitting the long data frame, it could then acknowledge the complete series of received data frames by transmitting a response frame with N(R) set equal to the current R value.
  • Page 82 Chapter 6 HDLC Data Link Layer transmit a response frame without being polled. The characteristics of a response are determined by the type of respond opportunity, the state of the node, and the mode within the state of the node. Asynchronous Respond Opportunity With two-way simultaneous transmission, each node always has an asynchronous respond opportunity (ARO).
  • Page 83 Chapter 6 HDLC Data Link Layer While in the LDS, the response capability of the node is logically disconnected from the data link; no data frames or supervisory response frames are transmitted or accepted. The response capability is limited to transmitting a disconnected mode (DM) response frame at each respond opportunity and accepting a set asynchronous balanced mode (SABM) command frame.

  • Page 84: Commands And Responses

    Chapter 6 HDLC Data Link Layer Data Transfer State While in the data transfer state (DTS), a node is fully operational and can transmit and receive data transfer, supervisory, and unnumbered format frames. In this state, the nodes are always in the asynchronous balanced mode (ABM).
  • Page 85 Chapter 6 HDLC Data Link Layer Time Control Field Bit No. N (S) N (R) Receive Sequence Number Modulo 8 Command: 1 = Poll Response: 1 = Final Send Sequence Number Modulo 8 Designates Data Transfer Format The data frame control field contains two sequence numbers: N(S) is the send sequence number which indicates the sequence number of the data frame containing the N(S).
  • Page 86 Chapter 6 HDLC Data Link Layer frame nor does it increment its receive variable (R) upon accepting a supervisory frame. The encoding of the control field in the supervisory format is as follows: Time Control Field Bit No. N (R) Code Designates Receive Sequence...
  • Page 87 Chapter 6 HDLC Data Link Layer Unnumbered Format Unnumbered commands are used to change mode. Unnumbered responses are used to acknowledge the change in mode. Unnumbered frames do not contain a data field. Therefore, a node does not increment its send variable (S) upon the transmission of an unnumbered frame nor does it increment its receive variable (R) upon accepting an unnumbered frame.

  • Page 88: Exception Condition Reporting And Recovery

    Chapter 6 HDLC Data Link Layer enter the ABM when it receives a SABM command, it transmits a disconnect mode (DM) response. From the time that one node sends a SABM command until the other node sends a response, the nodes are in the initialization state (IS). When a node transmits a SABM command or accepts a SABM command, it sets to zero its send and receive variables.

  • Page 89: Timeout Functions 6

    Chapter 6 HDLC Data Link Layer the node continues to be busy, it must respond with an RNR frame to each data or RR frame it receives. When a node receives an RNR frame, it will cease transmitting data frames at the earliest possible time by completing or aborting the frame it has in process.
  • Page 90 Chapter 6 HDLC Data Link Layer A node receiving REJ initiates sequential retransmission of data frames starting with the data frame indicated by the N(R) contained in the REJ frame. Timeout Recovery If, due to a transmission error, a node does not receive (or receives and discards) a single data frame or the last frames in a sequence of data frames, it will not detect an out-of-sequence exception;...

  • Page 91: Timeout Functions

    Chapter 6 HDLC Data Link Layer Mode Setting Contention A mode-setting contention situation exists when a node issues a mode-setting command and, before receiving an appropriate response (UA or DM), receives a mode-setting command from the other mode. Contention situations fall into one of the two following categories: When the send and receive mode-setting commands are the same, each node shall send a UA response at the earliest respond opportunity.
  • Page 92 Chapter 6 HDLC Data Link Layer Figure 6.4 represents the protocol environment with the source and transmitter at one end of the link and the receiver and sink at the other end of the link. Figure 6.4 Protocol Environment Network Packet Path 1 Network Packet SOURCE...
  • Page 93 Chapter 6 HDLC Data Link Layer Figure 6.6 shows a receive not ready (RNR) response to the initial message transmission because the message sink is full. After the message sink is no longer full, a retransmission of the message causes a receive ready (RR) response.

  • Page 94: Monitoring Transmissions

    Chapter 6 HDLC Data Link Layer Figure 6.8 shows an RR response which the transmitter has to discard. However, after the next data frame, the RR response serves as an acknowledgment for both data frames. Therefore, no frames are retransmitted. Figure 6.8 Message Transfer with an RR Response Discarded SOURCE...
  • Page 95 Chapter 6 HDLC Data Link Layer This data frame has an address of 1, a send sequence number of 3, and a receive sequence number of 7. The notation we use here to represent a supervisory frame is: 3,RR4 This receive ready frame has an address of 3 and a receive sequence number of 4.

  • Page 96: Summary

    Chapter 6 HDLC Data Link Layer This next example shows a large data frame being transmitted on one circuit, while several data frames are being transmitted on the other circuit. Then, while the 1,RR1 frame acknowledges one data frame, the 3,RR1 frame acknowledges seven data frames.

  • Page 97: Introduction To Message Sets

    Chapter Introduction to Message Sets Chapter Objectives In this chapter, you will read about the different message sets from which you can choose for sending and receiving messages between your host device and the 1779-KFM interface for communication across the Data Highway II network.
  • Page 98 Chapter 7 Introduction to Message Sets Time Critical Message Set You can send and receive time-critical messages between your host device and the 1779-KFM interface only if you select the Native mode. Time-critical messages can read from and write to host devices at remote stations.
  • Page 99 Chapter 7 Introduction to Message Sets PAD Message Set You can send and receive PAD messages between your host device and the 1779-KFM interface only if you select either the Native or PAD mode. The message header format depends upon which of these two modes you select.

  • Page 100: Network Through Application Layer

    Chapter 7 Introduction to Message Sets Network through Application In the communication protocols for the message sets we describe in the Layer following chapters, there are differences in the layers above the HDLC data-link layer. However, there are functions of these layers (network layer through application layer) that apply to all message-set protocols.
  • Page 101 Chapter 7 Introduction to Message Sets Program and Message Types The network protocol was designed on the assumption that application programs are of two types: command initiators and command executors. Corresponding to this division there are two message types: Command Messages — Initiated by command initiators and carried over the network to a command executor.

  • Page 102: Command Initiators/Executors

    Chapter 7 Introduction to Message Sets Command Initiators/Executors The application layer contains the command initiators and command executors. Command Initiators Create the command message and pass it on down for the network layer. Maintain the sequence number and timeout. Accept the reply message. Cancel the timeout and sequence number.

  • Page 103: Data Highway Message Set

    Chapter Data Highway Message Set Chapter Objectives In this chapter, you will read about the Data Highway message set. This chapter includes a description of the fields in each protocol layer above the data-link layer. It also describes each Data Highway message and the fields each message requires.
  • Page 104 Chapter 8 Figure 8.1 Data Highway General Format Native Fields Figure 8.1 shows the format of the Data Highway message packet, including the Native fields. These fields are common to all message transmissions in the Native mode. Here we describe these Native fields: Command Native Fields: Reply Native Fields:...
  • Page 105 Chapter 8 SEL (Select) — This one-byte field specifies the message set within the Native mode and distinguishes commands from replies. For Data Highway command messages, the hexadecimal value in this byte must be 03. For Data Highway reply messages, the hexadecimal value in this byte is 83.
  • Page 106 Chapter 8 In a command packet, these LINK, NODE, and USER fields combine to fully specify the network address of the remote station that is to receive the packet. In a reply packet, these fields specify the network address of the remote station sending the reply.
  • Page 107 Chapter 8 We show both the application-layer fields and the Data Highway fields to indicate where the application-layer fields fit into the message packet. Command Format: Success Reply Format: Error Reply Format: CMD (Command) and FNC (Function) — The low nibble of the CMD byte is an application-layer field.
  • Page 108 Chapter 8 If You Want This Command: Use This Command Code: Use This Function Code: Diagnostic Commands Basic Commands PLC 2 Commands PLC 3 Commands...
  • Page 109 Chapter 8 STS (Status) — The high nibble of the STS (status) byte is supplied by the application layer. In command messages the STS byte is set to 0. In reply messages, the STS field is used for reporting either application or network error codes.

  • Page 110: Diagnostic Message Formats

    Chapter 8 Diagnostic Message Formats In “Application Fields,” we described the Data Highway message fields defined at the application layer. Here, we describe the format of each specific type of diagnostic command message and reply message at the application layer. In each of these formats, we also show the Data Highway Fields to indicate where the application-layer fields fit in the message packet.
  • Page 111 Chapter 8 Diagnostic Read Use this command to read up to 244 bytes of data from the PROM or RAM of the interface. You can use it to read the interface’s diagnostic timers and counters. Use the diagnostic status command to obtain the starting address of the diagnostic counters.
  • Page 112 Chapter 8 The status information you receive in the DATA field varies depending on the type of interface supplying the information. Describes Information You Will This Table: Receive from This Interface:...
  • Page 113 Chapter 8 Table 8.A Status Information (in Hex) Received from a 1779 KP2 Interface Byte Value Meaning Mode of Programmable Controller Interface Type and Processor Type Interface Type Start of Program Diagnostic Counters Revision and Series Level of the 1779 KP2 Switch Settings Direct/Indirect Connection...
  • Page 114 Chapter 8 Table 8.B Status Information (in Hex) Received from a 1779 KP3 interface Byte Value Meaning Mode of Programmable Controller Interface Type and Processor Type Interface Type Current Context Module Number Mode Control Word Diagnostic Counters Revision and Series Level of the 1779 KP3 Last Word Used in Memory...
  • Page 115 Chapter 8 Table 8.C Status Information (in Hex) Received from a 1779 KFL Interface Byte Value Meaning Processor Type Interface Type Diagnostic Counters Revision and Series Level of the 1779 KFL Channel 1 Communication Parameters Channel 1 Mode and Protocol Channel 2 Communication Parameters Channel 2 Mode and...
  • Page 116 Chapter 8 Table 8.D Status Information (in Hex) Received from a 1779 KFM Interface Byte Value Meaning Processor Type Interface Type Diagnostic Counters Revision and Series Level of the 1779 KFM Communication Parameters Mode...
  • Page 117 Chapter 8 Set Response Timeout Use this command to set the maximum amount of time an interface will wait for a response to a message it sends to a host device. The time base is 40 ms, so a value of 19 hex sets the timer to 1 second. You can send this command to 1779-KFL interfaces only.
  • Page 118 Chapter 8 Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. Set ENQs Use this command to set the maximum number of ENQuiries an interface will send to a host if that host does not respond to a message from the interface.

  • Page 119: Basic Message Formats

    Chapter 8 Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. Reset Counters Use this command to reset to zero all the diagnostic counters and timers in an interface. Use the diagnostic status command to find the starting address for a block of counters and timers.
  • Page 120 Chapter 8 Protected Write Bit Use this command to set or reset specified bits within specified bytes within limited areas of data table memory in a programmable controller. Your access can be limited by memory access rungs in the communication zone of the controller’s ladder-diagram program.
  • Page 121 Chapter 8 Protected Write Block Use this command to write a block of data into limited areas of data table memory in a programmable controller. Your access can be limited by memory access rungs in the communication zone of the controller’s ladder-diagram program.
  • Page 122 Chapter 8 storage area of a programmable controller’s data table, and have the controller only read the byte, not control it. Command Format: Success Reply Format: Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. Unprotected Read Block Use this command to read a block of data from any area of data table memory in a programmable controller.

  • Page 123: Plc 2 Message Formats

    Chapter 8 Unprotected Write Block Use this command to write a block of data into any contiguous area of the data table in a programmable controller. Use the address (L ADDR) field to specify the logical byte address of where to start to write this block of data.
  • Page 124 Chapter 8 Enter Download Mode The enter download mode command puts the PLC-2 processor into the download mode. Use this command on a PLC-2 station before attempting to send any physical write commands to the station. Command Format: Reply Format: Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte.
  • Page 125 Chapter 8 Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. Exit Download/Upload Mode This command takes the PLC-2 processor out of the upload or download mode. Use this command to restart the PLC-2 processor after performing an upload or download operation.
  • Page 126 Chapter 8 Command Format: Success Reply Format: Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. Physical Read This command reads a block of data from the controller’s data table or program memory. Only use this command together with other commands in an upload or download procedure (“PLC-2 Upload/Download Procedures”).

  • Page 127: Plc 2 Upload/Download Procedures

    Chapter 8 Set Data Table Size This command sets the data table size for the PLC-2 processor. Before you send this command, you must send an enter download mode command (“Enter Download Mode”). Use this command immediately before performing any physical writes on the PLC-2 processor. For the DATA field in this command, enter the number of bytes of memory that you want to allocate to the PLC-2 data table.
  • Page 128 Chapter 8 access to the PLC-2 memory during a download if your download procedure follows this order: Enter Download Mode Set Data Table Size (if Required) Physical Write Physical Write Physical Read (Verification) Exit Download/Upload Mode If you download a program that requires a change in data table size, send a set data table size command before sending physical write commands containing the new program.
  • Page 129 Chapter 8 Program scan is inhibited. Programming terminal access is inhibited. A PLC-2/05, PLC-2/15, PLC-2/16, PLC-2/17, or PLC-2/30 processor is put into the program-load mode. With the last-state switch at each I/O chassis set to OFF, the outputs turn off. The outputs of a PLC-2/20 or Mini-PLC-2 processor remain enabled if the mode-select switch is in the RUN or RUN/PROG position.

  • Page 130: Plc 3 Message Packets

    Chapter 8 Timeout A two-minute timer will start when the 1779-KP2 interface receives an enter upload mode command or an enter download mode command. The timer will restart each time a command in the upload or download procedure is received. If the timer times out, the interface exits the mode as if an exit download/upload command were received.
  • Page 131 Chapter 8 Only a computer can initiate privileged commands. The primary function of these commands is to upload and download PLC-3 memory. In “Application Fields,” we showed the error-reply format. For PLC-3 messages, the error-reply message may have an additional field. If the STS field value is F0, an EXT STS field is added following the TNS field.
  • Page 132 Chapter 8 Command Format: Success Reply Format: Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. Read Block Use this command to read a block of words from the destination. Use the address (L ADDR) field to specify a starting logical word address; keep the address constant throughout a complete transaction.
  • Page 133 Chapter 8 Write Bit This command modifies the bits of the word specified by a logical address. This address must point to a word within a file. Unlike the unprotected and protected bit writes in the basic commands, this command can change the bits in a single word only. Command Format: Success Reply Format: Unless otherwise stated, values shown are in hexadecimal, and each block...
  • Page 134 Chapter 8 Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. Read File Use this command to read a file at the destination. Use the address (L ADDR) field to specify a logical file address. In the first packet of a transaction, the packet-offset value is 00.
  • Page 135 Chapter 8 Command Format: Success Reply Format: Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. Upload Privilege Use this command only as one step in the upload procedure described in “PLC-3 Upload/Download Procedures.” When the PLC-3 station returns a success reply, your computer has a privilege to upload from the PLC-3 memory.
  • Page 136 Chapter 8 memory. If your station has the upload privilege for a PLC-3 station, the shutdown command will cause the PLC-3 processor to turn off all outputs and go into the program-load mode. Command Format: Success Reply Format: Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte.
  • Page 137 Chapter 8 Physical Read Use this command only as one step in an upload procedure described in “PLC-3 Upload/Download Procedures.” Use the value in the address field (P ADDR) to specify the physical address of the start of the block of data to be read from the memory at the destination for this message packet.

  • Page 138: Plc 3 Upload/Download Procedures

    Chapter 8 Unless otherwise stated, values shown are in hexadecimal, and each block shown represents one byte. PLC 3 Upload/Download A common application for communication with a PLC-3 station is to Procedures upload and download the contents of the PLC-3 memory. To upload or download a PLC-3 memory, you must follow the procedures listed here.

  • Page 139: Chapter Summary

    Chapter 8 Diagnostic Status (to Detect the Last Memory Address Used) Upload Privilege Shutdown Physical Read Physical Read Restart Timeout A three-minute timer will start when the 1779-KP3 interface receives an upload-privilege command or a download-privilege command. The timer will restart each time a command in the upload or download procedure is received.

  • Page 140: Time Critical Message Set

    Chapter Time Critical Message Set Chapter Objectives In this chapter, you will read about the time-critical message set. This chapter includes a description of each field of each protocol layer above the HDLC data-link layer for time-critical messages. Selecting Time Critical Message Time-critical messages can read from and write to host devices at remote Sets stations.
  • Page 141 Chapter 9 below the application layer of the communication software, the data field is passed up to the next higher layer where additional fields are defined. Figure 9.1 Time Critical General Format Native Fields Figure 9.1 shows the time-critical message packet format including the Native fields.
  • Page 142 Chapter 9 Command Native Fields: Reply Native Fields: SEL (Select) — This one-byte field specifies the message set within the Native mode and distinguishes commands from replies. For time-critical command messages, the hexadecimal value in this byte is 0B. For time-critical reply messages, the hexadecimal value in this byte is 8B.
  • Page 143 Chapter 9 NODE — This one-byte field specifies the destination node (001 — 376 octal) for this packet within the destination link. The value of this field corresponds to the octal value you select with the LINK-ADDRESS thumbwheel switches at each node interface. USER —...
  • Page 144 Chapter 9 70 — Read Immediate-Access Block 72 — Read Block 73 — Write Bit with Reply 74 — Write Bit with No Reply 75 — Write Block with Reply 76 — Write Block with No Reply 77 — Unprotected Write Byte Command 78 —...

  • Page 145: Application Message Formats

    Chapter 9 command specifies a word address. This field is in each command message except a command to read an immediate-access block. The size of this field is variable (2 through 11 bytes). The first byte specifies the levels of addressing that are specified in the remaining bytes of the field. Refer to Appendix B for an explanation of logical addressing.
  • Page 146 Chapter 9 Command Format: In the reply, if the STS field has a value of 00, that indicates a successful- transaction reply which has a data field. The data field is the specified immediate-access block. The size of the block is determined by the programmable controller that generates it.
  • Page 147 Chapter 9 Read Block Use this command to read a block of data from the data table of the destination host’s memory. The maximum data field size is 38 bytes. Command Format: In the reply, if the STS field has a value of 00, that indicates a successful- transaction reply which has a data field (38 bytes max).
  • Page 148 Chapter 9 Write Bit With Reply Use this command to set or reset specified bits within specified words in the data table of the destination host’s memory. The fields following the CMD field consist of three-field blocks, each of which contains a logical-address field, followed by a two-byte AND-mask field and then a two-byte OR-mask field.
  • Page 149 Chapter 9 Reply Format: Write Bit with No Reply Use this command to set or reset specified bits within specified words in the data table of the destination host’s memory. The fields following the CMD field consist of three-field blocks, each of which contains a logical-address field, followed by a two-byte AND-mask field and then a two-byte OR-mask field.
  • Page 150 Chapter 9 The destination station does not send a reply to this command. Therefore, this command uses less network time than the write bit with reply command. However, with no reply, you have no assurance that the command is actually executed at the destination station. Write Block with Reply Use this command to write a block of data into the data table of the destination host’s memory.

  • Page 151: Summary

    Chapter 9 Command Format: The destination station does not send a reply to this command. Therefore, this command uses less network time than the write bit with reply command. However, with no reply, you have no assurance that the command is actually executed at the destination station. Summary In this chapter, you read about the time-critical message set.

  • Page 152: Remote Command Control Message Set

    Chapter Remote Command Control Message Set Chapter Objectives In this chapter, you will read about the remote command control message set. This chapter includes a description of each field of each protocol layer above the HDLC data-link layer for remote command control messages.
  • Page 153 Chapter 10 Remote Command 6 then remains stored at Node 2. Later, Node 1 sends a command to Node 2 to initiate Remote Command 6. Node 2 initiates Remote Command 6 by reading the data from Block A in the host PLC-3 memory, and then sending that data in write block command to Node 3.
  • Page 154 Chapter 10 At that point, a copy of Block A is in PLC-2/30 memory at Node 3. To enable the 1779-KFM interface to send and receive remote command control messages, you must set the communication-mode switches on the host board to select the Native mode. (Refer to Chapter 4 for switch-setting procedures).

  • Page 155: Packet Format

    Chapter 10 Packet Format To distinguish the remote command from the remote command control message containing it, we will often refer to the remote command control message as the RC control message. Figure 10.1 shows a data frame containing a remote command control packet in four layers: Fields of the remote command sent to be stored at the remote station (application layer).
  • Page 156 Chapter 10 Messages are initiated at the application layer and are placed into packets in the network layer. For outgoing messages, the packet from the network layer is passed down to the HDLC data-link layer and is sent out as the data field of the data frame.
  • Page 157 Chapter 10 RC Control Header Fields Figure 10.1 shows the format of the RC control message packet including the RC header fields. The RC control header fields are those header fields common to all RC control message set transmissions. Here we describe these RC control header fields: STS (RC Control Message Status) —...
  • Page 158 Chapter 10 command initiator of your host computer match each command with the corresponding reply. LINK — This one-byte field specifies the destination Data Highway II link (000 — 377 octal) within the network for this RC control message packet. With only one Data Highway II link in the network, enter the LINK-field value 000 octal.
  • Page 159 Chapter 10 message; it is not in the corresponding RC control reply message. The possible command-field hexadecimal values are: 00 — Store Remote Command 01 — Read Remote Command 02 — Initiate Remote Command 03 — Delete Remote Command 04 — Store/Initiate/Delete Remote Command RCQ (Remote Command Quantity) —...
  • Page 160 Chapter 10 Read — This three-bit sub-field specifies which stations are allowed to read the remote command. Code Stations Allowed Store — This three-bit sub-field specifies which stations are allowed to send a command to store a new remote command under this same ID without first deleting this remote command.
  • Page 161 Chapter 10 PWD (Password) — This four-bit sub-field specifies the code that must be used if the remote command is stored with one of the other protection sub-fields set to restrict access to anyone with the password. The password sub-field is in each RC control command. The complete remote command protection field is only in the store RC command and the read RC reply packet.
  • Page 162 Chapter 10 Write block is a protected command. That is, if its destination is a PLC-2 programmable controller, it can only access an area of data table memory designated by a memory access rung. LINK — This two-byte field specifies the destination Data Highway II link (000 —...

  • Page 163: Specific Message Formats

    Chapter 10 D SIZE (Destination Size) — This field specifies the number of bytes in the block of memory affected at the ultimate destination station which executes the remote command. The size value must be even (02 through FF hexadecimal). D ADDR (Destination Address) —...
  • Page 164 Chapter 10 Reply Format: Read Remote Command Use this command to determine what remote command is stored at a remote programmable controller station under a specific remote command identification (RCID). Command Format: If the STS field in the reply header has a value of 00, that indicates a transaction-completed reply which has message fields for the application layer.
  • Page 165 Chapter 10 Error Reply Format: Initiate Remote Command Use this command to trigger a remote programmable controller station into initiating remote commands stored there. You can trigger the initiation of 122 remote commands maximum with one command. In the RCQ field, enter the number of remote commands to be initiated. Provide a separate pair of RCID and PWD fields for each remote command to be initiated.
  • Page 166 Chapter 10 If the STS field in the reply header has a value other than 00, that indicates an error reply which has no message fields for the application layer. Error Reply Format: Delete Remote Command Use this command to delete a remote command stored at a remote programmable controller station.

  • Page 167: Summary

    Chapter 10 Store/Initiate/Delete Remote Command Use this command to cause a remote programmable controller station to store, initiate, and then delete a remote command in immediate succession. Command Format: The reply has no message fields for the application layer. However, the STS field in the header indicates a successful transaction (00) or an error code.

  • Page 168: Pad Message Set

    Chapter PAD Message Set Chapter Objectives In this chapter, you will read about the PAD message set. This chapter includes a description of each field of each protocol layer above the HDLC data-link layer for PAD messages. Selecting PAD PAD messages let devices communicate over the Data Highway II network in a packet assembler/disassembler message format.
  • Page 169 Chapter 11 PAD Message Set passed up from and down to the HDLC data-link layer. At each layer below the application layer to the communication software, the data field is passed up to the next higher layer where additional fields are defined. Figure 11.1 PAD Format in Native Mode Data (Any Format)
  • Page 170 Chapter 11 PAD Message Set Command Native Fields: Reply Native Fields: SEL (Select) — This one-byte field specifies the message set within the Native mode. For PAD command messages, the hexadecimal value in this field is 06. For PAD reply messages, the hexadecimal value in this field is SSQ (Sub-Sequence Number) —...
  • Page 171 Chapter 11 PAD Message Set TNS (Transaction) — This two-byte field indicates which PAD message transaction is taking place. A complete transaction consists of the command packet and the corresponding reply packet. When the host computer initiates a transaction, it must increment the TNS value to distinguish the packets of the current transaction from the packets of the previous transaction.

  • Page 172: Using Native Mode Pad Messages

    Chapter 11 PAD Message Set Using Native Mode PAD When you send or receive a PAD command in the Native mode, it Messages contains all of the fields shown in Figure 11.1. The hexadecimal value of the SEL field is 06. The STS value is 00. The TNS value distinguishes it from other PAD commands generated by its message initiator.

  • Page 173: Packet Format For Pad Mode

    Chapter 11 PAD Message Set corresponding reply packets. The STS value is either 00 to indicate a successful transaction completion or a non-zero value to indicate an error. If you initiate a series of PAD command packets without waiting for each reply, there is no guarantee that the command packets will be delivered at the destination in the same order in which you sent them.

  • Page 174: Summary

    Chapter 11 PAD Message Set A host device for a 1779-KFM interface can send PAD messages to and receive PAD messages from a host device for a 1779-KFL or 1779-KFM interface at another Data Highway II station. The host device at the other station could be a dumb terminal, a robot, or a computer.

  • Page 175: Station Management Message Set

    Chapter Station Management Message Set Chapter Objectives In this chapter, you will read about: The fields you must include in station management messages. The network parameters you can control using station-management commands. The message format of each station-management command and reply. Selecting Station Management Station management messages let you configure and alter the network Messages...
  • Page 176 Chapter 12 Figure 12.1 Station Management General Format Native Fields Figure 12.1 shows the station management message packet format including the Native fields. The Native fields are those fields common to all message transmissions in the Native mode. Here we describe these Native fields.
  • Page 177 Chapter 12 SEL (Select) — This one-byte field specifies the message set within the Native mode and distinguishes error replies from commands and other replies. For station-management commands, their transaction-completed replies, and their command-error replies, the hexadecimal value in this byte is 08.
  • Page 178 Chapter 12 Below, we explain what each field specifies: UL (Use Layer) — This one-byte field specifies whether the command sets a parameter in the local node interface or in a remote node interface. If you want to set a parameter at the local node, enter a UL value of 0. If you want to set a parameter at a remote node of the local Data Highway II link, enter a UL value of 2.
  • Page 179 Chapter 12 Application Fields Figure 12.1 shows the station management message packet format including the application fields. The application fields are those station management message fields defined at the application layer. The application fields you use in a station management message will vary depending on the message you send.

  • Page 180: Application Message Formats

    Chapter 12 DATA — This variable-length field is preceded by a one-byte SIZ field. The SIZ field specifies how many bytes of data you are sending or receiving. The Data Size column in Table 12.A tells you the size of the data field you need to send.
  • Page 181 Chapter 12 Table 12.A Station Management Parameters Parameter Target Data Size Parameter Layer Value (in Bytes) Default Data (Hex) (Hex) (Decimal) (Hex) For All Interfaces For 1779 KFL Interfaces Only For 1779 KFL or KFM Interfaces Only For 1779 KFM Interfaces Only...
  • Page 182 Chapter 12 Token-Hold Factor — Determines the amount of time a node will hold the token and thus be able to transmit messages. Valid entries are 1 through 256 (1 through FF hex). The token-hold factor is a multiple of the token-hold time.
  • Page 183 Chapter 12 Remote-TC-Reply Timer — Determines the amount of time a KFL or KFM will wait for a time-critical reply message from a remote station before sending an error message to its host device. Data field is two bytes long. Time base 10 ms. Valid entries are 01 (10 ms) to FF FF hex (10 min.
  • Page 184 Chapter 12 Time-Critical Retries — Determines the number of times the interface will attempt time-critical commands that have not been successful. Data field is one byte long. Default is zero, valid entries are 00 to FF. Supervisory Retries — Determines the number of times the interface will attempt supervisory commands that have not been successful.
  • Page 185 Chapter 12 Table 12.B Node Management Parameters Location ID Data Size Default Data Parameter (LID) (Hex) (Bytes) (Decimal) (Bytes) (Hex) For All Interfaces For 1779 KFL Only For 1779 KFL, KFM Only For 1779 KFM Only...
  • Page 186 Chapter 12 Node management error codes are explained in Table 12.C. They are returned in the extended error status byte that follows the TNS byte in the reply. The status byte will contain an E0 (hex) if an error has occurred. Table 12.C Extended Status Error Codes Code...
  • Page 187 Chapter 12 For the read values command, you must include a DATA SIZE+1 field. To specify the value in this field, determine the number of bytes required for the parameter value you are reading and add one byte. The total is the value you specify.
  • Page 188 Chapter 12 Command Format: The reply to a set values request returns only the CMD field with a value of 81 hex, preceded by the reply header fields we described earlier. Remember that the reply header does not include a PWD field. Success Reply Format: Unless otherwise stated, each block shown represents one byte.

  • Page 189: Error Reply Messages

    Chapter 12 Error Reply Messages This section shows the error-reply messages you may receive after you send a station management command message. When sending a station-management command, you can experience two kinds of errors: Protocol Errors Command Errors Format Error Reply Message A format error occurs when the packet you send from the host computer to the KFM contains an error.
  • Page 190 Chapter 12 Command Error Reply Message Command errors occur when the KFM accepts the message from its host computer, but the destination interface cannot carry it out. Information about the error appears in the fields of the reply message. Here is the format of a command-error-reply message: Command Error Reply Format: The CMD-field value of 86 identifies this as a command-error message.

  • Page 191: Summary

    Chapter 12 OC (Operation Count) — This one-byte field is a zero-based index that points to an operation in the command, indicating that it was the operation being performed when the error was discovered. The value returned here will be 00 because you can only send one operation in a station-management command.

  • Page 192: Status Codes

    Appendix Status Codes What This Appendix Contains This appendix lists the hexadecimal codes that may appear in the status (STS), and extended status (EXT STS) fields of Data Highway II reply messages. The codes you receive can vary depending on which mode the interface is in and which type of command you sent.
  • Page 193 Appendix A Table A.A Hexadecimal Status Codes You May Receive in the STS Field of a Reply Message Status Code Meaning...
  • Page 194 Appendix A If a PLC-3 controller returns a value of F0 in the STS field, an additional field (EXT STS) will contain specific error code. Table A.B lists EXT STS codes for replies from PLC-3 controllers. Table A.B Hexadecimal Extended Status Codes You May Receive in the EXT STS Field of a Data Highway Message Set Reply from a PLC 3 Controller EXT STS Code...
  • Page 195 Appendix A Table A.D Hexadecimal Status Codes You May Receive in the STS Field of a Remote Command Control Reply Showing the Status of the Execution of the RC Control Command Status Code Meaning initiate...

  • Page 196: Data Manipulation

    This appendix describes how to address PLC-2 and PLC-3 programmable controllers. It also describes the order of data transmission. Addressing PLC 2 and PLC 3 The memory address of an Allen-Bradley programmable controller may Controllers take one of two forms—a logical address or a physical address.
  • Page 197 Appendix B Use this type of addressing when you send these commands to a PLC-2 station: Protected Write Block Protected Write Bit Unprotected Read Block Unprotected Write Block Unprotected Write Bit All Time-Critical Commands All Remote Command Control Commands When you send a time-critical or remote command control message to a PLC-2 station, the address field (L ADDR) has a variable length of two to four bytes.

  • Page 198: Plc 3 Logical Addressing

    Appendix B PLC 3 Logical Addressing Use the PLC-3 logical addressing format to send these PLC-3-type commands: Write Block Read Block Write Bit Write File Read File All Time-Critical Commands All Remote Command Control Commands You can use this format to specify up to six levels of PLC-3 extended addressing.
  • Page 199 Appendix B In Figure B.1, the Level 4 address is 260 (decimal), which is too large to fit in one byte. Therefore, a byte of all ones is used to delimit the two-byte address field for this level. The value 260 is then coded low byte first.
  • Page 200 Appendix B Figure B.2 PLC 3 Extended Addressing SYSTEM STATUS Context Section Word SYSTEM POINTERS Context Section Word MODULE STATUS Module Type Thumbwheel Switch Module Data DATA TABLE Context Section File Structure Word USER PROGRAM Context Section Rung Instruction Word MESSAGES Context Section...

  • Page 201: Physical Addressing

    Appendix B Physical Addressing Physical addressing is the type of addressing a computer would use with one of these physical commands: Physical Read (PLC-2 and PLC-3 Controllers) Physical Write (PLC-2 and PLC-3 Controllers) Diagnostic Read In particular, you would use physical addressing to upload or download programmable controller memory.

  • Page 202: Plc 3 Physical Addressing

    Appendix B PLC 3 Physical Addressing The physical addressing format applies to physical read and physical write commands. Physical word addresses run in sequence, starting with zero (0) for the first word of programmable controller memory. Physical addresses occupy 2 words (4 bytes), in the following bit format: In this format, A1 through A24 represent the 1 to 24 bits of the physical address.
  • Page 203 Appendix B This does not present a problem at programmable controller nodes on the link because programmable controllers always store and retrieve their data in this same order of low byte first. It can, however, require you to do some extra computer application programming to maintain the proper byte and word order in programmable controller data stored in a computer.
  • Page 204 Appendix B Figure B.4 Result of Transmitting Low Byte First PC Word 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00 0 1 1 1 0 1 1 0 16 Bit Computer Word with Right to Left Byte and Bit Order 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 0 1 1 1 0 1 1 0 16 Bit Computer Word with Left to Right Byte and Bit Order...

  • Page 205: Specifications

    Appendix Specifications Specifications Function Interfaces an intelligent asynchronous device to a Data Highway II link. Communication Channel to Host Device Type: RS-422/449 Communication Rates: 9.6K, 19.2K, 38.4K, 57.6K, 76.8K, or 115.2K bits/s Communication Channel to Data Highway II Type: Carrier Band Communication Rate: 1 million bits/s Power Requirements Voltage: 115V/230V AC Configurable...

  • Page 206: Error Counters

    Appendix Error Counters Chapter Objectives Error counters can provide you with a statistical summary of your network’s activity. At each Data Highway II interface (except the 1779-KP5 Data Highway II/Data Highway Plus interface), a set of counters is stored in memory to keep track of that node. You can access these counters by using the following command format: Each counter takes up four bytes.
  • Page 207 Appendix D The reply will come in the following format: size address size address Refer to Chapter 9 (“Diagnostic Read” section) in the 1779-KFL Asynchronous Interface User’s Manual for more information.
  • Page 208 Appendix D Table D.A Error Counters This Counter # And Is Accessible in the 1779 (Hex): Counts the Number of: KP2: KP3: KFL: KFM: Data Highway Commands PAD Commands Remote Command Blocks Time Critical Commands...

  • Page 209: Supervisory Message Format

    Appendix D Supervisory Message Format The message format for supervisory mode is shown below:...
  • Page 210 Index Attaching the Plugs on the Trunkline, 3 12 Operating the 1779-KFL Interface, Operation Switches, Connecting Communications Cables, 4 10 Connecting Power and Ground, 4 14 Planning the Layout for Installing the KFL, Cutting the Trunkline Cable, 3 11 Plugging into the Tap, 3 14 Power Distribution, 4 16...

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