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Allen-Bradley 1785-KE User Manual

Data highway plus communication interface module
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Allen Bradley
User Manual
1785-KE Data
Highway Plus
Communication
Interface
Module
(Cat. No. 1785-KE)
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Summary of Contents for Allen-Bradley 1785-KE

  • Page 1 Allen Bradley User Manual 1785-KE Data Highway Plus Communication Interface Module (Cat. No. 1785-KE)
  • Page 2 Table of Contents Using This Manual ....... Overview of the 1785 KE and Data Highway Plus .
  • Page 3 Table of Contents Communicating Through the 1785 KE Module ..1785 KE Diagnostic Tools ......Specifications .
  • Page 4 Table of Contents Using a Series A 1785 KE Module ....Interprocessor Addressing ......
  • Page 5 This manual describes the 1785-KE Data Highway Plus RS-232-C Purpose of This Manual Interface Module. It gives you procedures for:...
  • Page 6 Chapter 1 Series B Enhancements This manual describes both Series A and Series B versions of the 1785-KE module. Table 1.A lists the Series B enhancements to the module. These features were not available on the Series A version of the module. Where we describe these features later in the manual, we note that they are only available on the Series B version of the module.
  • Page 7 Important notes that stress information that is critical to your understanding and use of the product Related Products The 1785-KE Data Highway Plus RS-232-C Interface Module is part of the Data Highway Plus product family. Related products include: Product Catalog Number:...
  • Page 8 Chapter 1 Related publications For more information on the 1785-KE and the Data Highway Plus network, refer to the following documents: Publication Publication Number: The publications in the table above are available from Allen-Bradley. Contact your local Allen-Bradley sales office for more information.
  • Page 9 Chapter 2 Overview of the 1785 KE and Data Highway Plus In this chapter, we give you an overview of the 1785-KE module and how Chapter Objectives it interfaces with a Data Highway Plus network. What is the 1785 KE...
  • Page 10 Chapter 2 Figure 2.1 1785 KE Communication Interface Module What is Data Highway Plus? Data Highway Plus is a local area network (LAN) that allows peer-to-peer communication among up to 64 nodes. You use Data Highway Plus when you want to connect a small number of nodes on a common link. Data Highway Plus provides easy re-configuration and expansion if you want to add more nodes later.
  • Page 11 You can use your Data Highway Plus to connect such nodes as: RS-232-C devices attached to a 1785-KE or a 1770-KF2 Data Highway modules attached (via their RS-232-C port) to a 1785-KE or a 1770-KF2 a PLC-3 or PLC-3/10 attached to a 1775-S5,-SR5...
  • Page 12 Figure 2.2 A Typical Data Highway Plus Configuration Important: A computer connected to a 1785-KE module cannot access a node on a Data Highway through a 1785-KA module. Also, nodes on Data Highway cannot access a computer connected to a 1785-KE on Data Highway Plus.
  • Page 13 Chapter 2 The 1785-KE module automatically takes care of the data link layers on the Data Highway Plus network. This means that your application programs at the PLCs and computers do not need to bother with inter-node protocol, handshaking, or control of the Data Highway Plus link.
  • Page 14 Half-duplex protocol is used for a link between one master and one or more slaves. You must use modems for this type of link (unless there is only one slave). The 1785-KE module has slave mode capability only. You must provide the master function through a computer, or the 1771-KGM module.
  • Page 15 Chapter 2 Delivery Order of Commands If any node on a Data Highway Plus network initiates multiple commands (for example, the initiating node sets multiple bits at any time), the order in which those commands get executed at the remote node cannot be guaranteed.
  • Page 16 1785-KE Module”. A short discussion of each application follows: Figure 2.3 shows an example of using a 1785-KE to attach a computer or other intelligent RS-232-C device to Data Highway Plus. You attach the computer to Data Highway Plus using a point-to-point RS-232-C link.
  • Page 17 Chapter 2 You can use either full-duplex or half-duplex for the RS-232-C link. Figure 2.4 shows an example of using a 1785-KE (series B) to connect two Data Highway Plus networks over a point-to-point modem link. You must set the 1785-KE for full-duplex protocol in this application.
  • Page 18 Figure 2.5 shows an example of using the 1785-KE (series B) to connect a Data Highway Plus node (such as a PLC-5) to a multidrop network. The PLC-5 acts as a slave on the multidrop link. You must set the 1785-KE for half-duplex protocol and use modems.
  • Page 19 Chapter 3 Installing the 1785 KE Chapter Objectives This chapter explains how to install the 1785-KE module. There are four parts to installation: setting the communication option switches mounting the module connecting the module to the Data Highway Plus link...
  • Page 20 Chapter 3 Figure 3.1 Location of the Switch Assemblies on the 1785 KE Module Important: The 1785-KE Series B uses the convention DOWN (ON) = Binary 0, and UP (OFF) = Binary 1. 3–2...
  • Page 21 Chapter 3 Switch Assembly SW 1: Figure 3.2 shows the 1785-KE (Series B) set for: RS 232 C Link Features full duplex BCC error checking even parity embedded responses enabled detect and ignore duplicate messages ignore handshaking execute diagnostic commands Figure 3.2...
  • Page 22 Chapter 3 Switch 4 determines whether or not the RS-232-C port of the 1785-KE module can detect duplicate messages transmitted to it. If You Want the Module to: Set Switch 4: Switch 5 determines whether the RS-232-C port on the 1785-KE module uses and recognizes the following handshaking signals.
  • Page 23 Octal Digits 1 and 2 are used to set a Data Highway Plus node address for the 1785-KE module. The node address is an encoded 2 digit octal number that identifies the 1785-KE module as a unique node on Data Highway Plus.
  • Page 24 To set Set switches 6 8 Octal Digit Octal Digit 1 to: 2 to: No.3 No.4 No.5 No.6 No.7 No.8 Important: The 1785-KE Series B uses the convention DWN (ON) = Binary 0, and UP (OFF) = Binary 1. 3–6...
  • Page 25 No.5 Octal Digit 2 (Least Significant Digit) To set Octal Set switches 6 8 Digit 2 to: No.6 No.7 No.8 Important: The 1785-KE Series B uses the convention DOWN (ON) = Binary 0, and UP (OFF) = Binary 1. 3–7...
  • Page 26 Both switches must be DOWN for 57.6 Kbit communication rate. You use switches 3, 4, and 5 to set the communication rate for the RS-232-C link between your device and the 1785-KE (figure 3.6). Use the following table to set these switches.
  • Page 27 Set Switch 6 to: to Connect: Communications to a 1785-KE Series A is the same as that to a 1785-KE in local mode (i.e., when the 1785-KE Series B is in local mode, it functions the same as a 1785-KE Series A). As a result:...
  • Page 28 If the RS-232-C device is another Allen-Bradley communication module, you can mount the 1785-KE module up to 7,000 cable feet away from it by using the longline connection (discussed in Chapter 4). If you are using a modem link to connect the 1785-KE module to the RS-232-C device, then the module and the device may be as far apart as the modem link will allow.
  • Page 29 Chapter 3 Making Connections to The 1785-KE module has 3 connectors on its front edge (figure 3.8). the 1785 KE Figure 3.8 The Connectors on the 1785 KE 3–11...
  • Page 30 Figure 3.9 Connecting the 1785 KE to a Data Highway Plus Network If the 1785-KE is an end device in the Data Highway Plus Network, you must install a 150 ohm resistor on the 3-position terminal block or in the station connector (cat.
  • Page 31 Powering Up the 1785 KE When you have successfully: Module set the switch assemblies on the 1785-KE to the setting suited to your application mounted your 1785-KE module in a 1771 I/O rack following the procedure earlier in this chapter...
  • Page 32 For definitions of handshaking signals, refer to Appendix B. You connect your RS-232-C device to the RS-232-C PORT connector The RS 232 C PORT (figure 4.1) on your 1785-KE module. The RS-232-C PORT connector, a Connector female 15-pin D-shell, does not conform strictly to the RS-232-C standard, which specifies a 25-pin male connector.
  • Page 33 All other signals on the RS-232-C port are driven and received by standard RS-232-C interface circuits, which have maximum drive capability of 50 feet. The 1785-KE module sends data serially over the RS-232-C interface, one Character Transmission 8-bit byte at a time. The transmission format conforms to ANSI X3.16, CCITT V.4, and ISO 1177, with the exception that the parity bit is retained...
  • Page 34 When communication option switch 5 of switch assembly SW-1 (handshaking enable/disable) is set DOWN, the RS-232-C port of the 1785-KE module can transmit or receive all of the above signals (refer to Chapter 3 for switch setting information). If this switch is UP, then the RS-232-C port uses only TXD, RXD, and GND (TXDRET and RXDRET for longlines).
  • Page 35 Chapter 4 If you are connecting a 1785-KE module to a device not manufactured by Allen-Bradley, then you must mount the module within 50 cable feet of that device. For such applications, the module’s GND must be connected to the GND of the modem or computer. RXDRET must be jumpered to GND at the module.
  • Page 36 Chapter 4 Direct Connection to a To connect the module directly to a computer, you can use a data terminal interface cable (cat. no. 1770-CG). This cable plugs into the RS-232-C Computer PORT connector on the module and the RS-232-C compatible connector on the computer.
  • Page 37 Chapter 4 Connection to Another You can connect the 1785-KE to another Data Highway interface module with a longline cable. This cable can be up to 7,000 feet long. However, Communication Module remember that the cable length can limit the communication rate (refer to the section earlier in this chapter entitled Electrical Characteristics of the RS-232-C Port).
  • Page 38 Chapter 4 Figure 4.3 Connection to a 1771 KG Module Figure 4.4 Connection to a 1773 KA or 1775 KA Module 4–7...
  • Page 39 Chapter 4 Connection to a Modem To connect the module to a modem, you can use the modem interface cable (cat. no. 1770-CP). This cable plugs into the RS-232-C PORT connector on the module and the RS-232-C compatible connector on the modem. Connect the cable shield at one end only.
  • Page 40 Chapter 3), and the DCD signal is lost for more than approximately 10 seconds, the 1785-KE follows the handshaking sequence described in the section “Using the 1785-KE in an Auto-Answer Application” later in this chapter. If your modem does not support this sequence, you can either disable handshaking, or with handshaking enabled, jumper DTR to DSR at the module to insure the module will recover after DCD is restored.
  • Page 41 (DTE), controls the modem through the DTR, DSR, and DCD signals. The module incorporates timeouts and tests to properly operate these types of modems. See the section “Using the 1785-KE in an Auto-Answer Application” below for details. Auto-answer: These modems have self contained timeouts and tests, and can answer and hangup the phone automatically.
  • Page 42 Under this condition, a modem attached to the 1785-KE module will Auto Answer Application answer a call and assert DSR as soon as it detects ringing. The 1785-KE module does not monitor the RING indicator signal in the RS-232-C interface.
  • Page 43 The RS-232-C handshaking lines are used to control the switching of the carrier for a message transmission as follows (figure 4.6): Request to Send (RTS) -- sent from the Allen-Bradley module to the modem to indicate the module has a message to send and wants a carrier to be established.
  • Page 44 Chapter 4 Figure 4.6 A Typical Packet Transmission Using RTS, CTS, and DCD 4–13...
  • Page 45 Chapter 4 The modem you use to interface to an Allen-Bradley RS-232-C communication module (using half-duplex protocol) must be capable of: supporting standard RS-232-C handshaking described in this section and in Appendix B supporting the baud rate of your module...
  • Page 46 Chapter 5 Communicating Through the 1785 KE Module In this chapter, we discuss three typical applications of the 1785-KE Chapter Objectives module: connecting an intelligent RS-232-C device, such as a computer, to Data Highway Plus through a point-to-point RS-232-C link (local mode, full-...
  • Page 47 1785-KE on the Data Highway Plus, i.e., the computer and 1785-KE are addressed as a single node on the Data Highway Plus. As a result, messages sent from other nodes on the Data Highway Plus to the computer will use the address of the 1785-KE as the destination address.
  • Page 48 2. 1785-KE responds to computer: 3. 1785-KE sends command to the PLC-5: The 1785-KE sends the command onto Data Highway Plus and the PLC-5 node at address 51 (octal). 4. PLC-5 sends the reply to the 1785-KE: The PLC-5 receives the command, executes the command, formats a reply, and sends the reply back to the 1785-KE.
  • Page 49 The 1785-KE sends the command onto Data Highway Plus and the PLC-5 node at address 51 (octal). 4. PLC-5 sends the reply to the 1785-KE: The PLC-5 receives the command, executes the command, formats a reply, and sends the reply back to the 1785-KE. 5. 1785-KE sends the PLC-5 reply back to the computer:...
  • Page 50 The 1785-KE sends the command onto Data Highway Plus and the PLC-5 node at address 51 (octal). 4. PLC-5 sends the reply to the 1785-KE: The PLC-5 receives the command, executes the command, formats a reply, and sends the reply back to the 1785-KE. 5. 1785-KE sends the PLC-5 reply back to the computer: 6.
  • Page 51 The 1785-KE sends the command onto Data Highway Plus and the PLC-5 node at address 51 (octal). 4. PLC-5 sends the reply to the 1785-KE: The PLC-5 receives the command, executes the command, formats a reply, and sends the reply back to the 1785-KE. 5. 1785-KE sends the PLC-5 reply back to the computer:...
  • Page 52 Application 2: Figure 5.2 shows application involving communication between two Data Highway Plus networks through a full-duplex link between two Series B Communicating Between Two 1785-KE modules. Data Highway Plus Networks Figure 5.2 Connecting Two Data Highway Plus Networks 5–7...
  • Page 53 Chapter 5 When using a 1785-KE in this application, it should be set for Remote mode by setting the Remote/Local option switch (refer to Chapter 3). When in Remote mode, the Series B 1785-KE module allows any PLC on one of the Data Highway Plus networks to talk to any PLC on the other Data Highway Plus network.
  • Page 54 Chapter 5 PLC 5 Read Commands This example message instruction reads the eight words that were written to the remote PLC-5 (node 012) in the last example. The instruction stores these words in the integer file 7, word locations 10 through 17, of the local PLC-5 (node 010).
  • Page 55 Chapter 5 Program Verification To verify that the example programs above are executing properly, follow these steps: Look at the local PLC-5 (node 10 octal) file contents of integer file 7 by typing: N7:0 Change any value in word locations 0 through 7 in this file. The values appearing in word locations 10 through 17 should be the same as the values in word locations 0 through 7.
  • Page 56 The examples in this section discuss message transfers as they occur with a PLC-5 using a 1785-KE Series B. The 1785-KE acts as a slave on the multidrop and listens for messages addressed to a PLC-5 on its Data Highway Plus link. Thus, the master can send a message addressed directly to a PLC-5 and the 1785-KE will hear the message and pass it through.
  • Page 57 Data Highway Plus address on the Data Highway Plus link a slave node address on the master-slave multidrop network A single 1785-KE node address, used on both links, is selected by setting the appropriate switches on Switch Assembly SW-2 (see Chapter 3 for details on setting option switches).
  • Page 58 Note from the figure that three octal digits are available: Octal Digit 0, Octal Digit 1, and Octal Digit 2. Use Octal Digits 1 and 2 to set the 1785-KE’s Data Highway Plus address from 00-77. These digits also set the lower two digits of the 1785-KE’s address on the multidrop network.
  • Page 59 Chapter 5 PLC-2 Program Example Rungs 8 through 11 are timer values to write to and then read from the PLC-5. 5–14...
  • Page 60 Chapter 5 The following table summarizes the purpose of each rung in the example. For more information on 1771-KGM master programming, refer to the 1771-KGM User’s Manual (publication 1771-6.5.39). Rung: What It Does: To verify that the PLC-2 test program is executing properly, check the timer accumulator values in rungs 11 and 12.
  • Page 61 Chapter 5 Example 2: Slave to Master In this example, we send a message from the PLC-5 with Data Highway Plus address 011 (octal), through the 1785-KE at address 021 (octal), to the Communication master (1771-KGM/PLC-2) at multidrop address 014 (octal).
  • Page 62 Chapter 5 PLC 2 Unprotected Read This example reads the eight words that were written to the PLC-2 data table with the last example. This example stores the data in integer file 7, word locations 10 to 17. Program a message (MSG) instruction with the parameters shown below. Also, you must set up the message instruction for continuous mode by toggling bit N30:20/11 to ON.
  • Page 63 The 1785-KE at address 021 recognizes address 011 and passes the command through to the PLC-5 at that address. The PLC-5 at address 011 then executes the command, generates a reply, and sends it to the 1785-KE at address 021. The 1785-KE buffers the message and awaits a poll for address 011 from the master.
  • Page 64 The following examples show the T50 message instructions necessary to send PLC-5 Read and Write commands from the PLC-5 (address 013 octal) to the PLC-5 (address 011 octal) through the 1785-KE modules. PLC 2 Unprotected Write This example writes eight words from the local PLC-5 (address 013 octal) integer file 7, word locations 0 through 7, to the remote PLC-5 (address 011 octal) integer file 7 word locations 0 through 7.
  • Page 65 Chapter 5 Read Command This example reads the eight words that were written to the remote PLC-5 (address 011 octal) in the last example. The instruction stores the data in the local PLC-5 (address 013 octal) integer file 7, word locations 10 through 17.
  • Page 66 Since the 1785-KE Series B is transparent to the master, remote PLC-5’s can be polled as individual slaves whether there is one or multiple PLC-5’s attached to a given 1785-KE. As a result, PLC-5’s on a remote DH + can be polled as though they were individual slave stations. Figure 5.5 illustrates this application.
  • Page 67 Digit 1 to: No.1 No.2 Important: The 1785-KE Series B uses the convention DOWN (ON) = Binary 0, and UP (OFF) = Binary 1. Note from the figure that three octal digits are available: Octal Digit 0, Octal Digit 1, and Octal Digit 2.
  • Page 68 Chapter 5 Use Octal Digits 1 and 2 to set the 1785-KE’s Data Highway Plus address from 00-77. These digits also set the lower two digits of the 1785-KE’s address on the multidrop network. Octal Digit 0 is a multidrop address expansion digit. It sets the most significant (highest) digit of the 1785-KE multidrop address.
  • Page 69 1785-KE and PLC-5 addresses on the multidrop beyond the 00-77 (octal) limitation of DH+. The figure shows that all of the 1785-KE’s have address 21 octal on their respective DH+ networks. The PLC’s have addresses of 11 and 12 on their DH+ networks.
  • Page 70 Highway/Data Highway Plus Protocol and Command Set Reference Manual (publication 1770-6.5.16). There are 5 LED indicators on the front panel of the 1785-KE module Using the LED Indicators (figure 6.1). These indicators can help you in diagnosing problems with the module’s installation and operation.
  • Page 71 Chapter 6 The following table contains the meaning of each LED on the front panel of the 1785-KE. This LED: Lights: Note: If the RCVG LED remains lit and the XMIT LED appears to flicker, then the module is passing the token or sending messages.
  • Page 72 Counters what a diagnostic counter is how to read diagnostic counters what types of information the 1785-KE counters contain What is a Diagnostic Counter? A diagnostic counter records an event of interest for debugging the module and for longer term reliability analysis.
  • Page 73 Command Set Reference Manual (publication 1770-6.5.16). 1785 KE Data Highway Plus Diagnostic Counters The 1785-KE stores 29 diagnostic counters in a total of 35 bytes. The following table contains a list of 1785-KE Data Highway Plus diagnostic counter bytes and what they contain.
  • Page 74 Chapter 6 Counter Byte: What the Counter Contains: 6–5...
  • Page 75 Data Highway Plus: 57,600 bits per second RS-232-C Port: Switch selectable from 110 to 19200 bits/sec Functions Interface a programmable RS-232-C compatible device with an Allen-Bradley Data Highway Plus network Location 1771 I/O Rack Communicating Ports Data Highway Plus: 3-screw terminal block...
  • Page 76 Appendix B Definitions of RS 232 C Handshaking Signals The table below gives definitions for each signal: Signal: What it Does:...
  • Page 77 Appendix B Signal: What it Does: B–2...
  • Page 78 Replacing a Series A Module with a Series B Module If you are replacing a Series A 1785-KE with a Series B and want the operation to be compatible with your Series A module, set the Local/Remote switch on the Series B module to Local. Refer to Chapter 3...
  • Page 79 Appendix C Setting the Communication The Series A module has 6 switch assemblies (figure C.1 that enable you to select various communication options. The switch assemblies and their Option Switch corresponding options are: Select this switch assembly: For this communication option: Figure C.1 Location of the Assemblies on the Series A 1785 KE Module C–2...
  • Page 80 Appendix C Switch Assembly SW 1: RS 232 C Link Features Figure C.2 shows you the five switches in Switch Assembly SW-1: Figure C.2 The Switches on Switch Assembly SW 1 The following table shows you how to set switches 1, 2, and 5 for the module options you require.
  • Page 81 Appendix C Switch 3 determines whether or not the RS-232-C port of the Series A module can delete duplicate messages transmitted to it. If you want the module to: Set switch 3: Switch 4 determines whether the RS-232-C port on the Series A module uses and recognizes the following handshaking signals: data set ready (DSR) requests to send (RTS)
  • Page 82 Node Number Switch assemblies SW-3 and SW-4 are for setting the node number of the 1785-KE module. The node number is an encoded 2-digit octal number that identifies the Series A module as a unique node on Data Highway Plus. Valid node numbers for the Series A module are 00 to 77 octal.
  • Page 83 Appendix C Switch Assembly SW 5: Network Link Communication Rate Switch assembly SW-5 lets you select the communication rate for the Data Highway Plus port on the Series A module. Figure C.5 shows the switches on SW-5. Figure C.5 The Switches on Switch Assembly SW 5 Important: You must set both switches ON for SW-5.
  • Page 84 If the RS-232-C device is another Allen-Bradley communication module, you can mount the 1785-KE module up to 7,000 cable feet away from it by using the longline connection (discussed in Chapter 4.) If you are using a modem link to connect the 1785-KE module to the RS-232-C device, then the module and the device may be as far apart as the modem link will allow.
  • Page 85 Appendix C Making Connections to the The 1785-KE module has 3 connectors on its front edge (figure C.7). Series A 1785 KE Figure C.7 The Connectors on the Series A 1785 KE C–8...
  • Page 86 Appendix C You use the top connector, labeled PEER COMM INTFC, to connect the Series A 1785-KE to Data Highway Plus. Plug the 15-pin connector of your Data Highway Plus dropline into this connector. (For details on how to construct the dropline, refer to the Data Highway Cable Assembly and Installation Manual, publication 1770-6.2.1.)
  • Page 87 Appendix D Interprocessor Addressing Appendix Addressing This Appendix discusses the following: How to address a PLC-5 from a PLC-2 How to address a PLC-5 from a PLC-3 Communicating from a computer to a PLC-5 The PLC-2 does not understand the file structure of the PLC-5. When a How to Address a PLC 5 PLC-2 sends a message to a PLC-5, the data is either read from or written From a PLC 2...
  • Page 88 Appendix D Octal: Decimal Equivalent: PLC 5 Reserved File/File Type: Make sure that: if you use a communications module with a node address of 000 to 010 (octal) to communicate with a PLC-5 using PLC-2 commands, the module must be able to properly communicate to the corresponding file type listed in the previous table.
  • Page 89 Appendix D The PLC-5’s address is specified in the command rung of the PLC-2’s command code specifications: AAA – beginning word addresses (in octal) of the remote node processor for read/write operation. BBB – beginning word address (in octal) of the local node processor for read/write operation.
  • Page 90 Appendix D Addressing a PLC 5 When sending a command to a PLC-5 from a PLC-3, use the following guidelines to program the message instruction. From a PLC 3 The PLC-3 has six levels of addressing while the PLC-5 has only four levels.
  • Page 91 A computer can communicate with a PLC-5 on Data Highway Plus using Communicating From a the 1785-KE module. The table below gives a summary of PLC-5 data Computer to a PLC 5 table areas based on the type of commands your computer sends.
  • Page 92 Appendix D If your computer Then your computer access data from: executes: Modify PLC 2 Compatibility File D–6...
  • Page 93 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •...