Modbus/Tcp - YASKAWA IM 053MT Manual

Deployment

Modbus/TCP

4.9 Modbus/TCP
General
Telegram structure incl.
TCP/IP
Modbus/TCP
6byte header with number of
following bytes
Modbus/TCP header
(6byte)
Byte Name
0 Transaction identifier (High byte)
1 Transaction identifier (Low byte)
2 Protocol identifier (High byte)
3 Protocol identifier (Low byte)
4 Length field (High byte)
5 Length field (Low byte)
68
Modbus/TCP is a Modbus protocol put upon TCP/IP, where the IP address serves the
addressing. Modbus/TCP allows a client-server-communication, several clients may be
provided from one server.
The request telegrams sent by a master and the respond telegrams of the slave have the
same structure:
Slave address
1byte data
For send and receive telegrams, Modbus/TCP uses a header of 6byte with the following
structure:
Normally, byte 0 ... 4 have the value 0. You may also increase byte 0 and 1 in the slave
and thus establish an additional control.
Function code
1byte data
Description
Is sent back by the server (user-defined)
Is sent back by the server (user-defined)
Always 0
Always 0
Always 0 because messages < 256byte
Number of following bytes
HB300 | IM | 053-1MT01 | en | 19-40
VIPA System SLIO
Data
max. 254byte