Ch 2 Modbus Control Function - ICP DAS USA LinPAC-8000 User Manual

Modbus RTU／TCP Server User Manual for LinPAC / LinCon

CH 2 Modbus Control Function

This chapter is about how to consist your modbus requests, and how to interpret response
messages.
LinPAC／LinCon Modbus Server supports functions:
Function Code
01
02
03
04
05
06
15
16
108
In following sections, the defined Protocol Data Unit (PDU) is used within the framework of Modbus
RTU. For Modbus TCP protocol, there are 6 bytes of prefixed fields need be added.
Byte 0 Byte 1
Transaction identifier
Hi (0) Lo (0)
NOTE :
There are some address rules need to be noted :
(1.) Slot index start from 1, and max. is 8. (depended on your LinPAC／LinCon modules )
(2.) DI/O and AI/O points are dressed starting from 0.
Ver : 1.0 (2009.04)
Sub Code
- Read back multiple coils status (0xxxx) for DO
- Read multiple input discretes (1xxxx) for DI
- Read back multiple registers (4xxxx) for AO
- Read multiple input registers (3xxxx) for AI
- Write single coil (0xxxx) for DO
- Write single register (4xxxx) for AO
- Force multiple coils (0xxxx) for DO
- Write multiple registers (4xxxx) for AO
7 Read range code of ICPDAS AI/O module
8 Set range code of ICPDAS AI/O module
Byte 2 Byte 3
Protocol identifier
Hi (0) Lo (0)
Description
Byte 4 Byte 5
PDU length
Hi Lo
7
Byte 6 ～
PDU
Formate is defined in eache section
Section
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9.1
2-9.2
L2