Serial Protocol for RS-232 control of Industrial Relay Controller 16-Channel DPDT


I’m working on a project with this relay board, and need to control the relays from a Crestron RS-232 port. I’m looking for a document with the serial commands to turn each relay on and off individually. I don’t have access to the device itself, but I was told it was ordered with the RS-232 control interface.

Any help will be appreciated. Thanks!


Hi Brian,

Relay control commands are documented in this guide:

These commands are sent as byte values(not ASCII). The bytes documented in the guide are in Decimal format. For Crestron you need to convert the Decimal bytes to Hex bytes and escape them. Here is an example Crestron byte formatted command which will turn on relay 1:

The \x is the escape identifier for hex bytes. If you have any questions on this please let me know.

Thank you,
Travis Elliott

Thank you. Seems to be just what I was looking for. I’ll let you know if I have any further questions.


Had the chance to test this today, and did not have any luck controlling the relay board from Crestron. In this project, we need to turn all relays on and off together. The strings I’m using are:
(decimal) - 170 3 254 130 0 45
(Crestron Hex) - \xAA\x03\xFE\x1E\x00\x2D
(decimal) - 170 3 254 129 0 44
(Crestron Hex) - \xAA\x03\xFE\x1D\x00\x2C

The Crestron com port settings are 115200, N, 8, 1. When triggering the strings in Crestron Debugger, there is usually no reply from the relay board, but once in a while a single random byte is returned.

We are able to operate the relays from the Comm Operator software using these same strings

Any suggestions on what we might be missing?

Thanks, Brian

First make certain there are no software applications connected to the board other than the Crestron software. Only one software application can communicate with the board at a time. So if you have COMM operator open then Crestron would not be able to communicate with it.

You appear to be entering the correct commands in the correct format for Crestron. Many of our customers have used our products with Crestron in the past so it definitely works.

You might also make sure the Serial cable you are using to connect the board to Crestron is a Serial extension cable and not a Null modem cable.