Interfacing dmx controller to a plc


Thread Starter


We have a DMX Controller that need to be interfaced with a PLC (Siemens S7-400/Schneider Quantum/GE Fanuc). The DMX controller has RS232 port in it. It accepts serial port commands. The serial port commands are standard ASCII commands.<pre>
eg:-"i00" for status
"a00" to start a show
"b00" to stop a show</pre>
Please provide a help regarding how this device can be connected and interfaced with the PLC. The PLC is part of a SCADA system that monitors the entire process.

Please provide a solution

Luca Gallina

1. if you need to start a show by means of plain ASCII commands, any RS232 card is suitable. Depending on your PLC configuration, you may use also a Ethernet/RS232 converter.

2. on the other hand, if you want to have full control of the DMX data to be output, you can follow Mr. Ikhtiander indication for a Modbus-DMX gateway. Be aware that you must then set up a Modbus master interface at the PLC side.

To avoid Modbus hassle, not really necessary since DMX has no error control (it's just a stream with a sync delay in between), you may go straight from RS232 to DMX; run a quick google search for off-the-shelf devices.
The Loxone system would be helpful for you. Our system in one package is able communicate RS-232/485, Modbus and DMX as well have relays for switching. I would be happy to help if you have any questions.

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