ii
Table of Contents
Revision History ........................................................................................................................................... i
1
Introduction ..........................................................................................................................................1
1.1
Related Publications ...................................................................................................................2
1.2
Overview .....................................................................................................................................3
1.3
Trademark Registration ...............................................................................................................3
1.4
Remarks ......................................................................................................................................3
1.5
Symbols Used in this Instruction Manual ....................................................................................4
2
Precautions .........................................................................................................................................5
3
Unit Structure ......................................................................................................................................6
4
Communication Specifications ............................................................................................................7
4.1
Modbus RTU (RS-485) Communication Specifications ..............................................................8
4.2
Modbus TCP (Ethernet) Communication Specifications .............................................................8
5
Connection Specifications ...................................................................................................................9
5.1
System Configuration ................................................................................................................10
5.2
Wiring Procedure ......................................................................................................................12
5.2.1
Modbus RTU (RS-485) Wiring Procedure ......................................................................13
5.2.2
Modbus TCP (Ethernet) Wiring Procedure .....................................................................15
5.3
Communication Setup ...............................................................................................................17
5.3.1
DIP Switches ...................................................................................................................17
5.3.2
Status LEDs ....................................................................................................................22
6
Communication Protocol ...................................................................................................................23
6.1
Modbus Communication Protocol Overview .............................................................................24
6.1.1
Message Configuration ...................................................................................................24
6.1.2
CRC-16 Calculation (for Modbus RTU only) ..................................................................26
6.1.3
Communication Procedure .............................................................................................26
6.1.4
Modbus RTU Communication Interval ............................................................................28
6.1.5
Differences between Modbus TCP and Modbus RTU Protocols ....................................29
6.2
Function Codes .........................................................................................................................30
6.3
Response in the Event of an Error ............................................................................................31
6.3.1
Error Codes (Exception Codes) ......................................................................................32