Using Serial Communications

Serial RS-232 or RS-485 communication is only available on the RMC75S, and the Monitor port of the RMC75P.

Communicating via serial RS-232 or RS-485 from a PLC or HMI to the RMC75 consists of the following:

Reading RMC Registers
Writing to RMC Registers
Issuing Commands

This topic describes the basics of doing this with serial communications. All data in the RMC is stored in registers. Therefore, to communicate is to write to and read from registers in the RMC.

For information on setting up serial communications, see the Serial Overview topic.

Reading and Writing RMC Registers

To read from or write to RMC registers, simply write to the address of the register. The exact method will vary depending on the host controller you use, but the concept is the same.

Finding Addresses of RMC Registers

Use any of the following methods to find the address of a register in the RMC:

Use the Register Map topic. This topic lists all the user-accessible registers in the RMC. Make sure you use the correct address format for your communication protocol.
Use the address that is displayed in RMCTools. Many editors and windows in RMCTools display the address of the registers. Make sure you use the correct address format for your communication protocol.

Issuing Commands

See the Issuing Commands topic.

Reading Plots

For details on reading plots from the RMC, see the Reading Plots with a Host Controller topic.