Product Description XI/ON - Eaton Automation

XI/ON: Gateways for Modbus TCP 5 Implementation of Modbus TCP
Figure 31:
Schematic representation
of the
Modbus Communication
Stack
Schematic representation of the Modbus Communication Stack
(according to Modbus Application Protocol Specification V1.1 of
Modbus-IDA):
5.1.1 Protocol description
The Modbus protocol defines a simple protocol data unit (PDU)
independent of the underlying communication layers.
The mapping of Modbus protocol on specific buses or network can
introduce some additional fields on the application data unit (ADU).
Figure 32:
Modbus telegram
acc. to Modbus-
IDA
Modbus Application Layer
Modbus TCP
The Modbus application data unit is built by the client that initiates
a Modbus transaction.
The function indicates to the server what kind of action to perform.
The Modbus application protocol establishes the format of a
request initiated by a client.
54 M001973-01, 07/2007
TCP
others Modbus plus Master/Slave Client/Server
Physical layer
Physical layer
Rsxxx
Physical layer
IP
Ethernet
Physical layer