2
Modbus TCP protocol
© Copyright Reserved Autonics Co., Ltd.
19
2
Modbus TCP protocol
Modbus TCP is the communication using TCP/IP network consisting of MBAP(MODBUS
Application Protocol header) and PDU(Protocol Data Unit).
MBAP Header
(7 Byte)
Function code
(1 Byte)
Data
(n Byte)
MBAP Header is as following table.
Fields
Length
Description
Slave (Client)
Master (Server)
Transaction
Identifier
2 Byte
Transaction
identifier
Allots from Client
Copies and transfers
the received value
from the Master
Protocol
Identifier
2 Byte
Protocol identifier
(0 = MODBUS
protocol)
Allots from Client
Copies and transfers
the received value
from the Master
Length
2 Byte
Next data length
Next data length
(Unit: Byte)
Next data length
(Unit: Byte)
Unit Identifier 1 Byte
Identifier
Allots from Client
Copies and transfers
the received value
from the Master
TCP/IP communication port uses "502".
For more information about MODBUS TCP, refer
PDU
MODBUS TCP
Содержание krn100 series
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