Communication Network; Modbus Network; Supported Modbus Functions; Modbus Address - ICP DAS USA GW-7238D User Manual

4. Communication Network

4.1 Modbus Network

The GW-7238D, J1939 to Modbus Interface, supports the Modbus
RTU serial protocol. It plays a Modbus slave on the network.

4.1.1 Supported Modbus Functions

The Modbus function codes supported by the Modbus interface are
shown as the table below.
Table 4-1 Supported Modbus Function Codes
Function
Function Name
Code
Reading Holding
3 (03 Hex)
Register
Reading Input
4 (04 Hex)
Register
Preset Single
6 (06 Hex)
Register
Preset Multiple
16 (10 Hex)
Registers

4.1.2 Modbus Address

Only the areas of the Modbus I/O tables that are configured with
J1939 I/O data are addressable, Modbus functions that use Word
addressing addresses the I/O tables by using 16-bit words.
GW-7238D J1939 to MBTCP Server / MBRTU Slave Gateway User's Manual (Ver.1.1, May. 2013) ---
Description
Read multiple registers (4xxxx) for
AO
Read multiple input registers (3xxxx)
for AI
Write single register (4xxxx) for AO
Write multiple registers (4xxxx) for
AO
31