GE Industrial Solutions MX350 Communications Guide - Manual (Page 3)

TABLE OF CONTENTS
MX350 AUTOMATIC TRANSFER CONTROL SYSTEM – COMMUNICATIONS GUIDE 1
Table of Contents
Communications interfaces .........................................................................................1
RS485 interface (Modbus RTU) .....................................................................................2
Modbus Protocol...............................................................................................................................................2
Electrical Interface .......................................................................................................................................... 2
Data Frame Format and Data Rate ........................................................................................................ 2
Data Packet Format ....................................................................................................................................... 2
Error Checking................................................................................................................................................... 3
CRC-16 Algorithm ............................................................................................................................................ 3
Timing.................................................................................................................................................................... 4
MX350 supported functions ....................................................................................................................... 4
Modbus Functions............................................................................................................................................5
Function Code 01H ......................................................................................................................................... 5
Function Code 03H ......................................................................................................................................... 6
Function Code 04H ......................................................................................................................................... 7
Function Code 05H ......................................................................................................................................... 8
Function Code 06H .......................................................................................................................................10
Function Code 08H .......................................................................................................................................10
Function Code 10H .......................................................................................................................................11
Error Responses..............................................................................................................................................11
Performing commands using Function Code 10H ........................................................................12
Using the User Definable Memory Map ..............................................................................................13
Modbus memory map.................................................................................................................................14
Format codes ..................................................................................................................................................44
Ethernet interface ........................................................................................................66