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Allen-Bradley Data Highway II PLC-2 User Manual
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Allen-Bradley Data Highway II PLC-2 User Manual

Allen-Bradley Data Highway II PLC-2 User Manual

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Allen Bradley

User Manual

Data Highway II
PLC-2 Family
Interface
(Cat. No. 1779-KP2,
KP2R)

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Summary of Contents for Allen-Bradley Data Highway II PLC-2

  • Page 1: User Manual

    Allen Bradley User Manual Data Highway II PLC-2 Family Interface (Cat. No. 1779-KP2, KP2R)
  • Page 2 Table of Contents Using This Manual ....... Introducing the PLC 2/DHII Interface .

  • Page 3: Table Of Contents

    Table of Contents Installing the PLC 2/DHII Interface ....Programming the Local Host ..... . . Operation and Troubleshooting .

  • Page 4: Using This Manual

    PLC-2/DHII interface. Therefore, when we refer to the PLC-2/DHII interface in this manual, it applies to both. We only mention the redundant PLC-2/DHII interface in describing a difference. When referring to an Allen-Bradley programmable controller in this manual, we use the Allen-Bradley registered trademark PLC programmable controllers.
  • Page 5 PLC 2 family processor. Operation and Troubleshooting Operating and troubleshooting your KP2 interface. Chapter Summary This chapter told you about this manual. In the next chapter we introduce the Data Highway II PLC-2 Family Interface (Cat. No. 1779-KP2, -KP2R).
  • Page 6 Chapter Introducing the PLC 2/DHII Interface Chapter Objectives This chapter gives you an overview of the 1779-KP2 interface, its function, its application in a communication network, and the types of messages it sends and receives. What Is the PLC 2/DHII The PLC-2/DHII interface is a standalone unit consisting of: Interface? One Stationary Frame...
  • Page 7 Chapter 2 Introducing the PLC 2/DHII Interface Figure 2.1 PLC 2/DHII Interface with Removable Frame Separated from Stationary Frame Stationary Frame Removable Frame...
  • Page 8 Chapter 2 Introducing the PLC 2/DHII Interface Figure 2.2 Rear View of the Removable Frame Assembly Shield Power Supply Host Board Board Board 12617 What Is Its Function? The PLC-2/DHII interface functions as a communication interface between a PLC-2 family processor (host processor) and other nodes of a Data Highway II link (Figure 2.3).
  • Page 9 Chapter 2 Introducing the PLC 2/DHII Interface Compatible Processors The PLC-2/DHII interface is compatible with these PLC-2 family processors: Mini-PLC-2 Processor (Cat. No. 1772-LN1, -LN2, -LN3) Mini-PLC-2/05 Processor (Cat. No. 1772-LS,-LSP) Mini-PLC-2/15 Processor (Cat. No. 1772-LV) PLC-2/20 Processor (Cat. No. 1772-LP1, -LP2) PLC-2/30 Processor (Cat.
  • Page 10 Chapter 2 Introducing the PLC 2/DHII Interface Node Interfaces You can use these node interfaces on a Data Highway II link: Asynchronous Foreign-Device/DHII Interface (Cat. No. 1779-KFL) Redundant Asynchronous Foreign-Device/DHII Interface (Cat. No. 1779-KFLR) Synchronous Foreign-Device/DHII Interface (Cat. No. 1779-KFM) Redundant Synchronous Foreign-Device/DHII Interface (Cat.
  • Page 11 Chapter 2 Introducing the PLC 2/DHII Interface Stations/Nodes At each node interface, you must assign a unique link address to each node of the link. A host (computer or PLC processor, for example) and its interface to the Data Highway II link make up a station. A station is an input/output point in the communication system.
  • Page 12 Chapter 2 Introducing the PLC 2/DHII 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. We describe programming a host device for communication through a 1779-KFL interface in later chapters.
  • Page 13 Chapter 2 Introducing the PLC 2/DHII Interface Host/Interface Links In many applications, it is essential for nodes in a Data Highway II link to communicate with devices such as: Computers Color-Graphic Terminals Dumb Terminals Robots Computerized Numerical Controls (CNC) These devices must communicate through a local host/interface link and a node interface to the Data Highway II link to communicate with other nodes on the Data Highway link (Figure 2.5).
  • Page 14 Chapter 2 Introducing the PLC 2/DHII Interface enters a data field, the interface assembles the data field into the proper packet for the network to deliver the message to the computer. The PAD protocol is also useful for devices, such as robots, which have a fixed protocol.
  • Page 15 Chapter 2 Introducing the PLC 2/DHII Interface Bridges to Other Data Highway II At this time, the Data Highway II network does not have bridges to join Links Data Highway II links. However, we have designed the Data Highway II network with the flexibility to accommodate bridges at a later date.
  • Page 16 Chapter 2 Introducing the PLC 2/DHII Interface Reading a Block of Data You can generate two types of commands to read a block of data: Read Block Read Immediate-Access Block When a node interface receives a read block command from another node, it reads the specified area of the host’s memory;...
  • Page 17 Chapter 2 Introducing the PLC 2/DHII Interface Figure 2.6 Write with No Reply Message Transfer Command Message — Block of data to write into host at Node 2 Node Node Figure 2.7 Write with Reply Message Transfer Command Message — Block of data to write into host at Node 2 Node Node...
  • Page 18 Chapter 2 Introducing the PLC 2/DHII Interface Figure 2.8 Write Verified Message Transfer Command Message — Block of data to write into host at Node 2 Node Node Reply Message — Status of whether the write was successful Command Message — Read from host at Node 2 Reply Message —...
  • Page 19 Chapter 2 Introducing the PLC 2/DHII Interface Message Priority The two categories of message priority are: Supervisory Time-Critical You determine the priority of messages when you select the command you want to send. Most of the commands available have supervisory priority. (A write verified command always has supervisory priority.) However, certain read and write commands have time-critical priority.
  • Page 20 Chapter 2 Introducing the PLC 2/DHII Interface Generated Commands You can program the PLC-2/DHII interface to generate the following types of commands: Read Commands: - Read Block Write Bit Commands: - Protected Write Bit with No Reply - Protected Write Bit with Reply - Unprotected Write Bit with Reply - Protected and Verified Write Bit Write Block Commands:...
  • Page 21 Chapter 2 Introducing the PLC 2/DHII Interface Other Data Transfer There are more data transfer commands available on Data Highway II that can be generated with the KP2. They increase in complexity with the processor used. They still move data from one place to another, but they have different formats.
  • Page 22 Chapter 2 Introducing the PLC 2/DHII Interface Station Management The station-management commands change network parameters. Redundant Cabling If you install the redundant version of each node interface, you can install a second complete cabling system for the Data Highway II link (Figure 2.9).
  • Page 23 Chapter 2 Introducing the PLC 2/DHII Interface A Second Link You can provide two separate communication links for a PLC-2 family processor. For example, you can connect a 1771-KA2 module and a 1779-KP2 interface to provide both a Data Highway link and a Data Highway II link respectively through which the PLC-2 family processor can communicate (Figure 2.10).
  • Page 24 Chapter Installing Data Highway II Link Cabling Hardware Chapter Objectives In this chapter we explain how to install cabling hardware for a Data Highway II link. We tell you how to: Identify Hardware Plan Your Cabling Configuration Install - Taps - Trunkline - Droplines Identifying Hardware...
  • Page 25 Chapter 3 Installing Data Highway II Link Cabling Hardware Coaxial Cable Use RG-11 type coaxial cable for the trunkline. The RG-11 type coaxial cable has both a foil and a braided wire outer conductor (Figure 3.1). Figure 3.1 Coaxial Cable Braid Foil Inner Conductor...
  • Page 26 Chapter 3 Installing Data Highway II Link Cabling Hardware Figure 3.2 Local Tap Cable Plugs (2) Sleeve Body Trunkline Jack Dropline Jack Straight Plug Right-Angle Plug Dropline Cable Assembly Crimping Tool You will need the crimping tool for fastening the cable plugs to the trunkline cable segments (Figure 3.3).
  • Page 27 Chapter 3 Installing Data Highway II Link Cabling Hardware Terminator At each end of the trunkline, you will need a terminator to connect to a trunkline jack of the tap (Figure 3.4). Figure 3.4 Terminator Planning Cabling Configuration Before you install any hardware, carefully plan your cabling configuration.
  • Page 28 Chapter 3 Installing Data Highway II Link Cabling Hardware Figure 3.5 Cabling Configuration of a Data Highway II Link Trunkline Terminator Terminator Dropline Node Interface Figure 3.6 Relationship between Trunkline Length and Number of Nodes with Local Taps Length of Trunkline in Feet Number of Nodes with Local Taps...
  • Page 29 Chapter 3 Installing Data Highway II Link Cabling Hardware Bend Radius of Cables If you bend a coaxial cable sharper than the recommended minimum bend radius, you may decrease the reliability of the link. Plan your trunkline cable routing so that the cable will have no sharper bend than a minimum 6-inch bend radius (Figure 3.7).
  • Page 30 Chapter 3 Installing Data Highway II Link Cabling Hardware Tap Mounting Layout Figure 3.9 shows the mounting dimensions of a tap. However, you can mount a tap in any position or orientation. Mount each tap in a position convenient for your trunkline cable routing which will not violate the 6-inch minimum bend radius.
  • Page 31 Chapter 3 Installing Data Highway II Link Cabling Hardware bottom or left side of the node interface. Avoid routing the dropline cable over AC power terminals on the node interface. The PLC-3 interface module (1779-KP3) requires further restrictions because it is inside of the PLC-3 processor chassis. Mount the tap a maximum of 5 inches from the chassis.
  • Page 32 Chapter 3 Installing Data Highway II Link Cabling Hardware Figure 3.11 Local Taps Mounted Beside a Node Interface Use conduit for Trunkline the first 20 ft. from enclosure. Top of Enclosure Node Interface Droplines 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 33 Chapter 3 Installing Data Highway II Link Cabling Hardware Conduits Conduits provide protection from physical damage as well as an additional layer of protection from electrical interference for a coaxial cable. Route the trunkline cable through conduit for the first 20 feet above the enclosure.
  • Page 34 Chapter 3 Installing Data Highway II Link Cabling Hardware Figure 3.12 Cap on Dropline Jack of Tap without a Node Interface 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.
  • Page 35 Chapter 3 Installing Data Highway II Link Cabling Hardware Attaching 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 Data Highway II Link Cabling Hardware Figure 3.13 Attaching the Cable Plugs 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 Steps 9 and 10 Crimped Sleeve...
  • Page 37 Chapter 3 Installing Data Highway II Link Cabling Hardware 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 Chapter 3 Installing Data Highway II Link Cabling Hardware Figure 3.15 Trunkline Segments Connected to a Tap that Is Not at an End of the Link Trunkline Trunkline Segment Segment Dropline Installing Droplines After mounting the node interface (Chapter 4), pull the node interface out to the switch-setting position before connecting the tap to the node interface.
  • Page 39 Chapter 3 Installing Data Highway II Link Cabling Hardware Figure 3.16 Connecting the Dropline from the Node Interface to the Tap Node Interface Cap and Chain must not touch a conductive surface. Dropline Chapter Summary Once you have installed the Data Highway II link cabling hardware, you are ready to install the node interfaces.

  • Page 40: Installing The Plc 2/Dhii Interface

    Chapter Installing the PLC 2/DHII Interface Chapter Objectives This chapter presents procedures for: Planning the Layout Mounting the PLC-2/DHII Interface Setting Switches Connecting Communication Cables Connecting Power Read this chapter before you install the KP2 interface module. We provide steps for you to follow for proper installation. Failure to follow the steps provided may result in equipment damage.
  • Page 41 Chapter 4 Installing the PLC 2/DHII 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. Provide 6 inches minimum vertical separation between chassis and to top and bottom of the enclosure, with no chassis mounted above the C air temperature level (Figure 4.1).
  • Page 42 Chapter 4 Installing the PLC 2/DHII Interface Figure 4.1 Minimum Spacing for Necessary Air Flow for Cooling 2/30 C (140 F) at any point immediately below any chassis. This may limit how high chassis can be mounted in an enclosure. The temperature of the air must not excceed 60 10913 I...
  • Page 43 Chapter 4 Installing the PLC 2/DHII Interface Mounting the PLC 2/DHII Figure 4.2 shows the mounting dimensions for the PLC-2/DHII interface. Interface After drilling and tapping Interface the three holes in the enclosure backpanel, start the mounting bolt into the bottom hole. You can then hold the interface in place, resting it on the bottom bolt, while you start the top mounting bolts.
  • Page 44 Chapter 4 Installing the PLC 2/DHII Interface Setting Link Address On the front of the PLC-2/DHII 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 45 Chapter 4 Installing the PLC 2/DHII Interface Figure 4.4 Host Board Switches 1779 KP2/KP2R LEGEND Option Enabled Option Disabled White Is Depressed PROTECTION OPTIONS Accepts Writes to Program Area Accepts Writes to Data Table Accepts Network Parameter Changes Accepts Third Party Requests Reserved Reserved KP2 SPECIFIC OPTIONS...
  • Page 46 Chapter 4 Installing the PLC 2/DHII Interface Accept Writes to Program Area The accept-writes-to-program-area switch selections are: OFF — The interface rejects commands to write into the program area of the host. ON — The interface accepts commands to write into the program area of the host.
  • Page 47 Chapter 4 Installing the PLC 2/DHII Interface Setting MAC Board Switches The MAC board has two switches. Set Switch 1 to the UP position. Switch 2 is not used and can be in either position. To set the switch, follow these steps: With the removable frame in the switch-setting position, disconnect the green equipment-grounding conductor from between the stationary frame and the ground post on the removable frame...
  • Page 48 Chapter 4 Installing the PLC 2/DHII Interface Figure 4.6 MAC Board Switches Shield Down Power Supply Host Board Board Board 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.
  • Page 49 Chapter 4 Installing the PLC 2/DHII Interface To PLC Processor You must connect a cable from the PROCESSOR connector on the interface to the PLC processor (Figure 4.7). Use a 1771-CN or 1771-CO cable for connection to a Mini-PLC-2, Mini-PLC-2/05, or Mini-PLC-2/15 processor. Use a 1771-CR cable for connection to a PLC-2/20 or PLC-2/30 processor.
  • Page 50 Chapter 4 Installing the PLC 2/DHII Interface To Programming Terminal To use an Industrial Terminal with the PLC processor, connect a 1772-TC cable from the PROGRAM INTERFACE connector on the interface to the connector on the Industrial Terminal (Figure 4.8). With this connection you cannot use tape cassette functions through the Industrial Terminal.
  • Page 51 Chapter 4 Installing the PLC 2/DHII Interface To 1770 RG Module To use a PLC-2 Family Report Generation Module (Cat. No. 1770-RG) with the processor, connect a 1771-CN, -CO, or -CR cable from the PROGRAM INTERFACE connector on the interface to the PROCESSOR connector on the 1770-RG module (Figure 4.9).
  • Page 52 Chapter 4 Installing the PLC 2/DHII Interface To Second PLC 2/DHII Interface To use two PLC-2/DHII interfaces (for a second Data Highway II link) connect a 1771-CN, -CO, or -CR cable from the PROGRAM INTERFACE connector on the first interface to the PROCESSOR connector on the second interface (Figure 4.10).
  • Page 53 Chapter 4 Installing the PLC 2/DHII Interface To 1771 KA2 Module Another possibility of providing a second link is to connect a 1771-KA2 module (for a Data Highway link) in place of either the first or second interface in Figure 4.10. Connect a 1771-CN, -CO, or -CR cable from the PROGRAM INTERFACE connector on the first to the PROCESSOR connector on the second.
  • Page 54 Chapter 4 Installing the PLC 2/DHII Interface Connecting Power and Ground To connect the PLC-2/DHII 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 4.12).
  • Page 55 Chapter 4 Installing the PLC 2/DHII Interface 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 56 The power consumed by the PLC-2/DHII interface is 50W. Multiply the power requirements of the Allen-Bradley power supplies by 3, 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 57 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 58: Programming The Local Host

    Chapter Programming the Local Host Chapter Objectives In this chapter you will read about how to generate a ladder-diagram program for a PLC-2 family processor (local host) to communicate through the KP2 interface to the host of a remote node. The generation of commands is discussed as if transmitted to the PLC-2 family processor at a remote node.
  • Page 59 Chapter 5 Programming the Local Host Figure 5.1 Format of a Communication Zone START Header Rung Memory Access Rung Immediate Access Update Rung Read Immediate Read/Write Block Write Bit Delimiter Rung Program the header and delimiter rungs for each host processor.
  • Page 60 Chapter 5 Programming the Local Host Here are the communication zone rungs that go in your ladder diagram program: Rung to designate communication zone header (if a communication zone is needed). Rungs to define memory access (as needed). Rungs to update immediate-access blocks (as needed). Rungs to read immediate-access blocks (as needed).
  • Page 61 Chapter 5 Programming the Local Host Figure 5.2 Header Rung Address of Error Word Supervisory Local Timeout Node Preset Code Time Critical Timeout Preset Code Optionally a single GET will supply a single timeout for both supervisory and time critical. The address in the three GET elements in the header rung specify (from left to right): The Address of The Error Word...
  • Page 62 Chapter 5 Programming the Local Host Memory Access Rungs Memory access rungs define blocks of data table words which can be accessed with protected write commands from the remote node you specify. Protected write commands received from the specified remote node may access only those blocks of local data table words listed in memory access rungs.
  • Page 63 Chapter 5 Programming the Local Host Figure 5.3 Memory Access Example (A) Memory Access Branch (B) Local Host Data Table Showing Block Accessible to Protected Writes from Remote Node 010 Memory Access Block Boundaries in Local Host Data Table É É É É É Block Accessible É...
  • Page 64 Chapter 5 Programming the Local Host Figure 5.4 Typical Memory Access Rung Command Rungs The command rungs direct the PLC-2/DHII interface to send command messages to remote nodes. Each command rung lists the type of command and the bits or block of words affected. You initiate a command message through the ladder-diagram program.
  • Page 65 Chapter 5 Programming the Local Host Figure 5.5 General Command Rung Remote Station Start Bit Refer to Figure 5.6 & Figure 5.7 Command Code Supervisory Time Critical Protected Write Block with Reply Protected Write Block with Reply Read Block Read Block Protected Write Bit with Reply Protected Write Bit with Reply Unprotected Write Block w/Reply...
  • Page 66 Chapter 5 Programming the Local Host General Block Command Format Use the format shown in Figure 5.6 when you enter a command code specifying any of the following commands: Read Block Protected Write Block with No Reply Protected Write Block with Reply Protected Write Block Verified Unprotected Write This format uses three GET elements.
  • Page 67 Chapter 5 Programming the Local Host Figure 5.6 General Block Command Format Remote Station Local Station Start Bit Data Table Boundaries Command Code Remote Station Starting Data Table Address Legend Beginning Word Address at REMOTE Station for WRITE/READ Operation Beginning Word Address at LOCAL Station for WRITE/READ Operation Ending Word Address at LOCAL Station for WRITE/READ Operation Bit Command Format Use the format shown in Figure 5.7 when you enter a command code...
  • Page 68 Chapter 5 Programming the Local Host Figure 5.7 Bit Command Format Remote Station Start Bit Area may contain any legal combination of these instructions. Branch End Command (If Needed) Code Branch Start (If Needed) Legend EEEEE -] [- Turn ON the Addressed Bit at the Remote Station. -] / [- Turn OFF the Addressed Bit at the Remote Station.
  • Page 69 Chapter 5 Programming the Local Host The link designation tells what link the remote node is on. It allows you to send messages off the local link via bridges when you have bridging capability. The node designation is the address of the remote node within its local link.
  • Page 70 Chapter 5 Programming the Local Host For example, in Figure 5.3 we show a rung that designates only the remote node on the local link: If you were to designate a remote station that is on Channel 2 of a KFL interface, you would have to add a user designation: If you were to designate a remote station that is on another link (Link 3), you would have to add a link designation:...
  • Page 71 Chapter 5 Programming the Local Host Figure 5.8 Immediate Access Update Rung Immediate Access Block Boundaries in Local Host Data Table (21 Words Max.) Starting Ending Address Address Start Bit Local Node Immediate Access Block Number The EXAMINE-ON, GET, and EXAMINE-OFF elements in the immediate-access rung specify the following: The bit address of the EXAMINE-ON instruction specifies the start bit that controls when the PLC-2/DHII interface reads the...
  • Page 72 Chapter 5 Programming the Local Host Should you require multiple immediate-access rungs, enter them in succession in the communication zone, immediately following any memory-access rung and before any command rung. Read Immediate Access Block Use the format shown in Figure 5.9 when you enter a command rung to specify a command to read an immediate-access block.
  • Page 73 Chapter 5 Programming the Local Host Notice the format used in the read and update immediate: The format is: get the data and put it here. Read Update Examine Start Bit Assign a unique start bit to each command rung. The start bits are examined by the PLC-2/DHII interface.
  • Page 74 Chapter 5 Programming the Local Host Refer to Figure 5.10. You specify the addresses of these status words when entering the communication zone rungs. A pair of start/done and remote/local fault words is defined by the selection of the start bit in a command rung.
  • Page 75 Chapter 5 Programming the Local Host Select the start bit for any command in the upper byte (Bits 10-17) of the start/done word. The done bit for this command is then the corresponding bit in the lower byte (Bits 00-07) of the same word. In Figure 5.11.A, the sample command rung examines Bit 03210 as its start bit.
  • Page 76 Chapter 5 Programming the Local Host As it name implies, the done bit indicates command completion. This bit, controlled by the PLC-2/DHII interface, is set ON when the execution of a command is completed successfully. Each command rung must examine a unique start bit. Thus, a single pair of start/done and remote/local fault words has enough bits for up to 8 command rungs.
  • Page 77 Chapter 5 Programming the Local Host Figure 5.12 Remote/Local Fault Bit Significance Processor Local Fault 2/30 Possible Sources: Power Off at Remote Node Interface Unused Remote Node Number Addressed Node Interface at Local or Remote Node Has Disconnected Itself as a Result of Link Monitoring Automatic Timeout at Local Node Local Node...
  • Page 78 Chapter 5 Programming the Local Host Immediately before it sets a remote or local fault bit ON, the PLC-2/DHII interface enters a four-digit error code into the error code storage word. The error code storage word is described in the discussion on “Error Word.”...
  • Page 79 Chapter 5 Programming the Local Host Appendix B lists status codes. Error codes can be grouped as follows: Codes D2 through E7 indicate that the PLC-2/DHII interface has detected some programming error in the communication zone of the program. The program status indicator (PROG ERR) will be ON if one of these codes is displayed.
  • Page 80 Chapter 5 Programming the Local Host Because Codes D2 through E7 are intended for start-up situations and Codes 10 through CF are intended for situations subsequent to power-up, there is no conflict in controlling this upper byte of the error code storage word.
  • Page 81 Chapter 5 Programming the Local Host Normal Operation Command execution begins when the ladder-diagram program turns on a start bit, normally with a latch instruction. The PLC-2/DHII interface detects the ON state of this bit and then begins the operation necessary to format and transmit a command message.
  • Page 82 Chapter 5 Programming the Local Host Table 5.A Start/Done Bit Status Status Start Bit Done Bit Significance Idle Command initiated or in progress. Command/reply operation complete. The processor, based on the program, acknowledges completion of the command/reply operation (transient condition, since the KP2 interface turns the done bit OFF in its next scan).
  • Page 83 Chapter 5 Programming the Local Host Figure 5.15 Start/Fault Bit Timing Faulted Operation É É É É É É É É É É É É É Start Bit ON É É É É É É É É É É É É É É...
  • Page 84 Chapter 5 Programming the Local Host To turn off the start bit, the program examines the response from the PLC-2/DHII interface. This response may be one of the following: Done Bit Remote Fault Bit Local Fault Bit Next we describe commonly used forms of start bit control. Each discussion concerns a different method for initiating command execution.
  • Page 85 Chapter 5 Programming the Local Host ON/OFF Input Status You can use the ON or OFF status of an input device to latch the start bit. Figure 5.16 shows example rungs for this type of command initiation. Figure 5.16 Status Initiated Command Remote Local Start...
  • Page 86 Chapter 5 Programming the Local Host In some applications, it may be useful to send a command continuously between stations. You can accomplish this by adding an EXAMINE-OFF instruction for the done bit as in Figure 5.17. This would cause the command to be sent continuously as long as Input 11111 remains ON.
  • Page 87 Chapter 5 Programming the Local Host Figure 5.18 Transition Initiated Command Rung 1 Transition Input Compare Input Compare Rung 2 Compare Input Rung 3 Transi Remote Local Start tion Fault Fault Done Rung 4 Start Done Timed You can turn on the start bit periodically to send a command at a user- determined interval.
  • Page 88 Chapter 5 Programming the Local Host Figure 5.19 Timer Initiated Command Done PR 010 AC 000 Timed Remote Local Start Fault Fault Retry Delay In some cases, automatic retry, as implemented in Figure 5.16, Figure 5.18, and Figure 5.19, can load down the network unnecessarily. Message transfer attempts that result in local faults can take many times as much time as the normal message transfer time.
  • Page 89 Chapter 5 Programming the Local Host Figure 5.20 Retry Delay Rung 1 Transition Input Compare Input Compare Rung 2 Compare Input Rung 3 Transi Start tion Timeout Done Rung 4 Local Remote Fault Fault PR 050 Rung 5 AC 000 Transition Done Monitoring Remote/Local Fault Bit...
  • Page 90 Chapter 5 Programming the Local Host The ladder-diagram program must monitor the remote and local fault bits for each command. The recommendations that follow concern two methods for monitoring fault bits and using these bits to signal a fault condition. Diagnostic Fault Rungs The purpose of remote/local fault bit monitoring is to control one or more output indicators to signal a fault condition.
  • Page 91 Chapter 5 Programming the Local Host Output Indicator Remote Fault Local Fault Output Indicator Done This example shows the fault bit monitoring for as many as eight commands. The eight remote fault bits and the eight local fault bits reside in Word 033.
  • Page 92 Chapter 5 Programming the Local Host The OFF-delay timer is useful in this application because it is continually reset when its rung conditions go true. This means that the timed bit, Bit 03015, remains on for a long as any fault bit is changing state during programmed retries.
  • Page 93 Chapter 5 Programming the Local Host interface to monitor command execution time without using timer (TON) instructions in the program. Figure 5.23 shows the significance of the timeout preset interval. From the time the start bit is set ON, the PLC-2/DHII interface must set either a done bit or a remote or local fault bit within the timeout preset interval.
  • Page 94 Chapter 5 Programming the Local Host Programming Preset Code You enter the timeout preset code in the header rung of the communication zone of program. The address field of the second GET instruction (and the optional third GET for a time-critical timeout) in this rung is used for the timeout preset code.
  • Page 95 Chapter 5 Programming the Local Host If it is necessary to use some value other than those provided in Table 5.B, compute the 3-digit timeout preset code with the following steps: Select a timeout preset interval. This interval must be larger than 1/2 second at intervals of 1/2 second.
  • Page 96 Chapter 5 Programming the Local Host Figure 5.24 Typical User Programmed Timeout Done Start Remote Fault PR 100 AC 000 Local Fault Output Indicator Timed Bit In the first rung of this figure, Timer 060 times the interval between the setting of the start bit for a command and the done, local fault, or remote fault response of the PLC-2/DHII interface.
  • Page 97 Chapter 5 Programming the Local Host There may be other instances where program monitoring of commands is useful. In some cases, you might program a timeout to monitor the execution time of critical commands. An application may require that a time-critical message, such as a command to read an immediate-access block, be sent within a certain limited amount of time.
  • Page 98 Chapter 5 Programming the Local Host Write bit commands are generally used to set storage bits in the data table of a remote node. These storage bits can then be examined in the program as conditions to energize an output bit. This indirect programming technique not only allows control using write bit commands, but also helps to prevent the confusion that can result if you attempt to control a bit directly from both an output energize instruction and a write bit...
  • Page 99 Chapter 5 Programming the Local Host Therefore, when using the write bit command, address only bits within a byte which are set aside exclusively for control by these commands. Note that this byte restriction for write bit commands does not apply to any but the PLC-2 family processors.

  • Page 100: Operation And Troubleshooting

    Chapter Operation and Troubleshooting Chapter Objectives This chapter provides the following: A description of the function of each LED indicator and switch on the front panel for operating the 1779-KP2 interface. Procedures for operating the 1779-KP2 interface. Procedures for narrowing down the source of the problem when a problem occurs within the local node.
  • Page 101 Chapter 6 Operation and Troubleshooting Figure 6.1 KP2 Front Panel NODE PASS MAC FAULT HOST FAULT NODE TEST MAC TEST TEST RESET ACTIVITY NORM LINK ADDRESS ACTIVE PROGRAM COMM ERR INTERFACE EXIT COMPLETE PROG. ERR PROCESSOR PROC. ERR EXIT REQUEST G IN RING SEEKING MEM DUP ADDR...
  • Page 102 Chapter 6 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.
  • Page 103 Chapter 6 Operation and Troubleshooting Operation Switches The interface has three switches on its front panel for you to use in operating the interface (Figure 6.1). 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 104 Chapter 6 Operation and Troubleshooting In the RUN position, the interface can communicate with other nodes of the Data Highway II link. When you power up the interface in the RUN position, it first 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 105 Chapter 6 Operation and Troubleshooting Whenever you want to turn off interface power or switch out of the RUN position, 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 106 Chapter 6 Operation and Troubleshooting Figure 6.2 Green Conductor Connecting the Stationary Frame to the Ground Post on the Removable Frame 115V AC/230V AC INTERNALLY SWITCH SELECTABLE L2/N Green Grounding Conductor Disconnect the cables from the front of the interface. Loosen the four thumbscrews on the front of interface.
  • Page 107 Chapter 6 Operation and Troubleshooting Figure 6.3 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 6.4).
  • Page 108 Chapter 6 Operation and Troubleshooting Figure 6.4 Locking/Ejecting Levers on Connectors Levers 11. Push the lever apart with your thumbs to eject the cable from the connector on the board. 12. Remove all three ribbon cables. CAUTION: Electrostatic discharge can damage circuit board components.
  • Page 109 Chapter 6 Operation and Troubleshooting 13. Remove five screws to remove the power-supply board. 14. Remove five screws to remove the host board. 15. Remove power-supply and host-board screws to remove the MAC board. 16. With the screws removed, you can slide the faulted board straight out the back of the removable frame.
  • Page 110 Chapter 6 Operation and Troubleshooting Troubleshooting the Interface When you suspect that the interface is not functioning properly, follow these steps (Figure 6.6). Check the AC POWER ON indicator. OFF — If off, check the AC POWER switch setting, fuse, AC source voltage, and interlock switch.
  • Page 111 Chapter 6 Operation and Troubleshooting OFF — If off, turn the AC POWER switch off, wait 20 seconds and turn the AC POWER switch on. If still off, try replacing each of the three boards until you find the faulted one. ON —...
  • Page 112 Chapter 6 Operation and Troubleshooting Figure 6.6 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 Step 2 POWER OFF, wait 20 seconds, then set the AC power switch to ON.
  • Page 113 Chapter 6 Operation and Troubleshooting Error Codes You’ll find a complete list of error codes in Appendix B of this manual. Chapter Summary In this chapter, we gave you information about individual indicators and switches, as well as procedures for using them to operate the interface. We also provided procedures for troubleshooting and for replacing faulty boards.

  • Page 114: Specifications

    Appendix Specifications Specifications Function Interfaces a PLC-2 programmable controller with Data Highway II Installation Standalone Mounting with Independent Power Supply Program Panel Interconnect Cable (Cat. No. 1772-TC) Data Highway Processor Cable (Cat. No. 1771-CR) Communication Rate 1 megabit per second over Data Highway II Cabling RG-11-Type Coaxial Cable for Data Highway II (See Publication 1779-6.3.1)

  • Page 115: Error Codes

    Appendix Error Codes Chapter Objectives This appendix lists error codes, grouped according to the error-code type: Link-Layer Error Codes Time-Critical Error Codes Local Errors Remote Errors KP2 Prescan Error Codes Error Codes Link Layer Code Meaning MAC board memory buffer is full at remote interface. Remote interface is off line.
  • Page 116 Appendix B Error Codes Time Critical Code Meaning Host device at remote node has faulted. Memory address specified doesn't exist in host device at remote node. Data in write command is larger than area assigned or data in read command is smaller than amount requested.
  • Page 117 Appendix B Error Codes KP2 Prescan Error Codes Code Meaning Message transmission successful. PC not responding. Switched back to program mode. Meaningless rung in communication zone. Program ends before a delimiter rung is found. Block number in update command missing. Too many rungs in communication zone (either highwater or number of rungs exceeds 255).