MODBUS TCP is an open industry standard widely spread due to its

ease of use. It is a request-response protocol and offers services

specified by function codes.

MODBUS TCP combines the MODBUS RTU with standard Ethernet

and the universal networking standard TCP. It is an applicationlayer

messaging protocol, positioned at level 7 of the OSI model.

The CI867A/TP867 is used for connection between an AC 800M

controller and external Ethernet devices using Modbus TCP

protocol.

The CI867 expansion unit contains the CEX-Bus logic, a

communication unit, and a DC/DC converter that supplies

appropriate voltages from the +24 V supply via the CEX-Bus. The

Ethernet cable must be connected to the main network through an

Ethernet switch.

The CI867A only uses one Ethernet port (100 Mbit/s) compared

with the earlier CI867. where two Ethernet ports could be used (100

Mbit/s and 10 Mbit/s). The CI867A module will only work with

System 800xA 6.0.3.3. 6.1.1. and subsequent versions.