GW-7238D J1939 to MBTCP Server / MBRTU Slave Gateway User’s Manual (Ver.1.1, May. 2013) ---
47
Or
Without have to control the Modbus register 42009 (Dec), just enable
Auto transmission function in J1939 configuration area as below, and
upload to GW-7238D.
Figure 5-13: J1939 Auto Transmission function screen
5.4 Modbus Communication – Modbus TCP
Set J1939 output data
Using the Modbus command as below:
FC16 Write multiple registers (4xxxx) for AO
[Request] (Request by Modbus master device)
Byte 0-1
: Transaction Identifier (Usually zero when making a
request)
Byte 2-3
: Protocol Identifier (Protocol number. Must be zero)
Byte 4-5
: Length (Number of following bytes - upper
/
lower
byte)
Byte 7: Net ID (Station number)
Byte 8: FC=10 (Hex)
Byte 9-10: Reference number
Byte 11-12: Word count
Byte 13: Byte count (B=2 x word count)
Byte 14-(B+13): Register values
[Response] (Response from the GW-7238D)
Byte 0-1
: Transaction Identifier (Usually zero when making a
request)
Byte 2-3
: Protocol Identifier (Protocol number. Must be zero)
Byte 4-5
: Length (Number of following bytes - upper
/
lower
byte)