GE Industrial Solutions EPM4500 Submeter - Manual (Page 44)

4–2 EPM 4500 SUB METER – INSTRUCTION MANUAL
MODBUS COMMUNICATIONS CHAPTER 4: COMMUNICATIONS
FIGURE 4–1: RS-485 Serial Connections
Note
The EPM4500 optical port is disabled for units with 2-wire RS485 connections.
4.1.2 RS232 Wiring for Modbus
The wiring for Modbus communications for RS232 is indicated below.
4.1.3 Modbus Commands
The EPM4500 is capable of acting as a remote slave unit to a Modbus master device via
modem, RS232, RS485, or PLC. Up to 32 EPM4500 meters (or other RS485 devices) can be
daisy-chained together on a single LAN.
The EPM4500 communicates at a default baud rate of 19200, with no parity and 1 stop bit.
The default Modbus address is 100. Changes to the default baud rate or address can be
accomplished through the configuration file upload.
The following Modbus commands are supported by the EPM4500:
• 03: Read R4 type register(s)
• 06: Write single register; address “0” is used as the broadcast address
• 16: Write multiple registers; address “0” is used as the broadcast address
4.1.4 Fixed Modbus Values
The EPM4500 provides fixed register values indicating the meter's serial number, the
meter's version number, and the Modbus addresses.
709725A1.CDR
Color Function DB-9 Pinout
Black TX 2
Red RX 3
Green GND 5