I have a pair of ZADSR32xPROXR with a serial RS-232 board. I want to use a ESP32 to connect to the relay board and setup an MQTT topic to control it. Can you tell me what type of connection is the Dout/Din pins in the relay board?
The Din/Dout pins on that board are the RS232 Rx/Tx lines(You can google XBee pinout to see those two connections). They are 3.3VDC so you should be able to connect them to the ESP32 module along with a GND connection so you have Serial communication between the relay board and the ESP32.
If you have any other questions on this please let us know.
All relay control commands are documented in this guide:
Thinking about this further I think if I were in your shoes I would have the ESP32/ProXR board subscribe to a Command topic and publish to a topic called something like Response. This way the software controlling the device over MQTT could simply send the commands documented in the guide above through the Command topic and get command responses from the board through the Response topic. I think that’s the quickest and simplest way to accomplish this.
Ive done some MQTT work through ESP32. I used this library: https://pubsubclient.knolleary.net
It works great. Also the callback handler for the topics use byte arrays which is perfect since our board is expecting commands in byte format, this means you just take the bytes received by the MQTT callback handler and send them right out the serial connection. I think you could have this all up and running pretty quick.