Allen-Bradley 2080-LC20-20AWB, User Manual

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Rockwell Automation Publication 2080-UM005E-EN-E - March 2018
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Communication Connections Chapter 5
Modbus RTU
Modbus is a half-duplex, master-slave communications protocol. The Modbus
network master reads and writes bits and registers. Modbus protocol allows a
single master to communicate with a maximum of 247 slave devices. Micro800
controllers support Modbus RTU Master and Modbus RTU Slave protocol. For
more information on configuring your Micro800 controller for Modbus
protocol, refer to the Connected Components Workbench Online Help. For
more information about the Modbus protocol, refer to the Modbus Protocol
Specifications (available from http://www.modbus.org ).
See Modbus Mapping for Micro800 on page 189 for information on Modbus
mapping. To configure the Serial port as Modbus RTU, see Configure Modbus
RTU on page 67 .
CIP Serial Client/Server (RS232 only)
CIP Serial Client/Server allows CIP protocol to be used over an RS232 serial
port. It is typically used with modems. The advantage over non-CIP serial
protocols is that since the protocol is CIP, program downloads are supported
including CIP pass-through from the serial port to Ethernet.
ASCII
ASCII provides connection to other ASCII devices, such as bar code readers,
weigh scales, serial printers, and other intelligent devices. You can use ASCII by
configuring the embedded or any plug-in serial RS232 or RS485 port for the
ASCII driver. Refer to the Connected Components Workbench Online Help for
more information.
To configure the serial port for ASCII, see Configure ASCII on page 69 .
TIP
Use MSG_MODBUS instruction to send Modbus messages over
serial port.