ICPDAS GW-7238D User Manual page 49

Byte 4-5:
Byte 6:
Byte 7:
Byte 8:
Byte 9-(B+8):
Example:
Read a value of one word in the address 30001.
[Request] (Byte0, Byte1... Byten) (Hex)
00 00 00 00 00 06
GW-7238D responds a value of one word in the address 30001.
[Response](Byte0, Byte1... Byten) (Hex)
00 00 00 00 00 05
Start or Stop sending J1939 output message
Using the Modbus command as below:
FC6 Write single register (4xxxx) for AO
[Request] (Request by Modbus master device)
Byte 0-1:
Byte 2-3:
Byte 4-5:
Byte 6:
Byte 7:
Byte 8-9:
Byte 10-11:
[Response] (Response from the GW-7238D)
Byte 0-1:
Byte 2-3:
GW-7238D J1939 to MBTCP Server / MBRTU Slave Gateway User's Manual (Ver.1.0, Nov. 2011) --- 49
Length (Number of following bytes - upper /
lower byte)
Net ID (Station number)
FC=04
Byte count of response (B=2 x word count)
Register values
01 04 00 00 00 01
01 04 02 12 34
Transaction Identifier (Usually zero when making a
request)
Protocol Identifier (Protocol number. Must be zero)
Length (Number of following bytes - upper / lower
byte)
Net ID (Station number)
FC=06 (Hex)
Reference number
Register value
Transaction Identifier (Usually zero when making a
request)
Protocol Identifier (Protocol number. Must be zero)