Communication instructions Chapter 9
Rockwell Automation Publication 2080-RM001D-EN-E - February 2015 257
The MSG_CIP function blocks support different communication protocols as
described in this section.
Function block support for message communication protocols
The following table lists the communication protocols supported by the Modbus
and CIP message function blocks.
Messaging Protocol Communication media Use this function block
Modbus/RTU client and server Through a Serial port configured as Modbus RTU MSG_MODBUS on page 197
Modbus/TCP client and server Over the Ethernet instead of through a serial port MSG_MODBUS2 on page 204
Ethernet IP client and server Through an embedded Ethernet channel MSG_CIPSYMBOLIC on page 183
MSG_CIPGENERIC on page 174
CIP Serial client and server Ethernet cable or Serial cable MSG_CIPSYMBOLIC on page 183
ASCII Through an RS-232 port configured with an ASCII driver See ASCII serial port instructions on
page 109
Modbus RTU
Modbus is a half-duplex, master-slave communications protocol that allows a
single master to communicate with a maximum of 247 slave devices. The Modbus
network master reads and writes bits and registers. Modbus RTU is supported by
configuring the Serial port as Modbus RTU.
For more information about the Modbus protocol, refer to the Modbus Protocol
Specifications (available from http://www.modbus.org).
Modbus/TCP
The Modbus/TCP Server communication protocol uses the same Modbus
mapping features as Modbus RTU, but it is supported over the Ethernet instead of
through a Serial port.
The Micro850 controller supports up to 16 simultaneous Modbus TCP Server
connections. No protocol configuration is required other than configuring the
Modbus mapping table.
support
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