Serial Communications Overview

Serial RS-232 or RS-485 communication is supported by the RMC75S CPU module, allowing the RMC75S to interface to other devices such as HMIs and PLCs. The RMC performs as a slave, requiring a master to control it. It always waits for a request from a master serial device before responding.  It does not initiate communications.

The RMC150 does not support serial RS-232 or RS-485. However, the RMC150E can communicate to serial RS-232/485 devices via serial-to-Ethernet converters, available from manufacturers such as Lantronix (UDS100-IAP) or Allen-Bradley (1761-NET-ENI). Contact Delta for more information.

The RMC75S has two communication ports, which can be used simultaneously:

 

For basics on using serial communications, such as reading and writing registers and issuing commands, see the Using Serial Communications topic.

Features

The RMC75S serial port 1 has a great amount of flexibility, as summarized below:

Setup

Because of the large number of options offered by the RMC75, setting it up can be intimidating to users new to serial communications. Read each of the following topics carefully before designing your serial network:

Configuring the RMC7xS Serial Communications

Line Drivers: RS-232/485

Serial Network Topologies

RS-232 Wiring for the RMC75

RS-485 Wiring for the RMC75

RS-485 Termination and Biasing

Protocols

The following topics describe how to use each protocol supported by the RMC75S:

DF1 (Full- and Half-Duplex)

Modbus/RTU

Mitsubishi Bidirectional Protocol

Using Serial Communications

See the Using Serial Communications topic.

 

See Also

Communications Overview


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