782-JDM DeviceNet™-Modbus Gateway User’s Manual W estern Reserve Controls, Inc.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual Although every effort has been made to insure the accuracy of this document, all information is subject to change without notice. WRC takes no liability for any errors in this document or for direct, indirect, incidental or consequential damage resulting from the use of this manual. Document PUB 24.0 Rev 1.04 October 2000 Copyright © 1999, 2000 WRC Western Reserve Controls, Inc.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual TABLE OF CONTENTS 1 OVERVIEW ............................................................................................................................................................................ 3 1.1 FEATURES............................................................................................................................................................................4 1.2 DEVICE NET SYSTEM A RCHITECTURE ........................
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual LIST OF TABLES TABLE 1-1 DATA M ESSAGE OPTIONS...........................................................................................................................................5 TABLE 2-1 A DDRESS SELECTION ..................................................................................................................................................7 TABLE 2-2 JDM SERIAL PORT CONNECTION ....................................................
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual PRELIMINARY 1 Overview The 1782-JDM is a family of DeviceNet-to-Modbus interfaces that allows you to easily connect and integrate a Modbus-capable device into a DeviceNet system. The Modbus device’s real-time data is read and written as I/O by the DeviceNet Master via Polled I/O. The devices set up parameters, if any, can be read and written with the Explicit Messaging technique.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual 1.1 Features The JDM has the following features: • Translates messages and data between DeviceNet and Modbus devices • Operates independently of operation of Modbus device • Forwards the message received without interpretation • Each JDM communicates with one or more Modbus devices • ODVA Conformance tested to DeviceNet Spec 2.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual 1.3 JDM Basic Operation The JDM operates as the DeviceNet front-end gateway between the DeviceNet system and the Modbus devices. It is a DeviceNet server device that can be assigned by the system implementer to one specific master. The DeviceNet Master can receive and send data to and from the JDM via the methods described in this section.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual How do I send a poll command to read data? The poll command can read multiple Modbus Device status registers’ data per poll command, as supported by the device, up to a limit of 100 bytes of data on the DeviceNet message. First, set up your scanner to read the number of bytes of data expected from the JDM plus two (2), depending upon the command and number of register data desired.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual PRELIMINARY 2 Quick Start To quickly and easily install your JDM in your DeviceNet system, follow the instructions below. For more details, see Section 2.3. To Install and Establish DeviceNet Communications 1. Connect the DeviceNet cable to the 5-pin plug (supplied) according to DeviceNet cable wiring specifications. 2. Make sure that the DeviceNet network is terminated properly. (See Section 3.5 below.) 3.
Western Reserve Controls PUB 24.0 2. 1782-JDM User’s Manual Switch setting changes do NOT take effect until the device is reset with either a device RESET command (to the class 1 Identity object) or a power cycle. 2.2 How to Change the DeviceNet Baud Rate 1. The baud rate defaults to autobaud.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual 2.4 How to Read Modbus Device Input Data 1. Set up the poll input data field size in your Master’s scan table to be equal to or greater than the number of bytes required for the largest Modbus message received from your device(s). (default size is 48 bytes). 2. Set up a Poll Connection (Allocate Connection Instance 2) to the 1782-JDM from the Master. 3.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual 2.5 How to Write Modbus Device Output Data 1. Configure the port to send output data by setting the size of the poll output buffer at the Master to reflect the number of output bytes that will be sent to the Modbus device (default is 48 bytes). 2. Perform a poll function that has the first byte of the field as the “record number”, which the host application must increment each time a new record is to sent to the Modbus device.
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Western Reserve Controls PUB 24.0 1782-JDM User’s Manual PRELIMINARY 3 Hardware Installation and Configuration 3.1 Overview The ASCII contains two LEDs to indicate the status of the device and the status of the network. The device can be connected to the main DeviceNet trunk line or to a drop line via screw terminations on the open, pluggable 5-pin DeviceNet connector supplied with your unit. The serial link, RS232 or RS485, is connected via an open, pluggable 3-pin connector. 0.984 (25) 3.540 (89.9) 0.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual 3.2 LED Operation A ASCII Multiplexer has two LEDs that provide visual status information to the user about the product and the DeviceNet network. See Table 3-1 and Table 3-2. Table 3-1 Module Status LED (labeled MS) LED State Module Status Meaning OFF No Power There is no power through DeviceNet. Green Device Operational ASCII is operating normally.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual 3.3 RS232/RS485 Connector Your Modbus device(s) are connected to the JDM via 3-wire communications cable. See your Modbus device User Manual for details on the specific connection. Table 3-3 Serial Port Connections Pin # RS232 Signal RS485 Signal Designator 1 Transmit Signal + SIG+ 2 Receive Signal - SIG- 3 Ground Ground GND 3.4 Power Requirements 3.4.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual 3.5.1 Network Termination A DeviceNet system must be terminated at each end of the trunk line. The host controller and the last JDM or other DeviceNet device on the network must always be terminated to eliminate reflections, even if only two nodes are present. The DeviceNet specifications for the terminating resistor are: • 121 ohm • 1% metal film • 1/4 Watt An appropriate terminating resistor kit, WRC part number RM121DN, is included with your JDM.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual The conductor sizes for DeviceNet cables are: Table 3-6 DeviceNet Conductor Sizes Function Thick Wire Thin Wire Power 15 AWG 22 AWG Signal 18 AWG 24 AWG Figure 3-2 DeviceNet cable connector Figure 3-3 DeviceNet cable specifications 3.6 Software Configuration The ASCII Multiplexer is software-configured for several parameters.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual Table 3-7 Configuration Parameters Parameter Param.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual Definitions of these parameters are as follows: 1. Modbus Mode: The JDM can operate in either the ASCII or RTU mode for Modbus communications. 2. Rx Data Length: Maximum number of bytes expected from the remote Modbus device. Note that the DeviceNet produce length will read this length + 2. 3. Tx Data Length: Maximum number of bytes to be sent to the remote Modbus device. Note that the DeviceNet consume length will read this length + 1. 4.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual PRELIMINARY 4 DeviceNet I/O Assembly Formats The following tables define the format of the DeviceNet data sent to and received from the JDM. The exact format of the output and input data that is sent from and received at your DeviceNet master is defined by the Modbus command used. The following tables provide the general format and illustrate the differences between the ASCII and RTU modes.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual Table 4-2 I/O Assembly Object Instance 2 Data Format – Short Command w/o Fragmentation Byte (Offset value) 0 1 2 3 4 5 6 7 Data 3F (hex) Record number Address Command Data www – LSB Data www – MSB Data xxx – LSB Data xxx – MSB 4.2 Input Data, Modbus Response The exact format of the input data that is received at your DeviceNet master is defined by the Modbus command used.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual PRELIMINARY 5 General Specifications Product: 1782-JDM – DeviceNet-to-Modbus Gateway Description: Communications gateway between a Modbus device over an RS232 or RS485 network and a Devi ceNet network.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual Network Status: green/red bi-color LED Network Termination: External terminating resistor (optional per user system configuration) Serial port: Baud rate: 1200, 2400, 4800, 9600, 19.2k, 39.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual PRELIMINARY 6 Accessories and Other WRC Products The following components can be used with a 1782-JDM-x for replacements or spare parts, or as complementary devices as a part of your DeviceNet system.
Western Reserve Controls PUB 24.0 1782-JDM User’s Manual PRELIMINARY 7 Troubleshooting This section identifies some of the common problem observed when commissioning or operating a DeviceNet and JDM. Problem: JDM powers up. The module LED flashes green. The network LED is OFF. JDM does not communicate over the network. Possible Solution: The JDM is in Autobaud mode, and is waiting for a few messages to cross the network so it may determine the baudrate setting.
