Sending control data to nodes


I am building myself an Opentherm to emonCMS gateway  to monitor and control the communication between my Intergas boiler and Remaha central heating controller.  It is now working nicely and I am able to monitor the communication and pass the data up to emonCMS over RF69 radio.

The next step is to pass control information back again to tell the gateway to override the controller and set its own heating strategy.  I am able to successfully pass data from a minicom terminal to the device using the format


Now I would like to do the same thing from the emonCMS api as described at

On using the api to send packets they are sent in the format


which is not recognised by my receiver.

Is this a bug or am I doing something wrong?

In the long term I would prefer to send control packets directly via MQTT.  Is there a way to do this?


I have worked out how to send MQTT messages directly to emonhub using nodeRED, but they still go out to the radio in the wrong format.



derek_j's picture

Re: Sending control data to nodes

I have hacked  to change the format of the command sent to the radio, and now it works OK and I can receive commands to my node.


Python is not my forte, but here is the change made to the function send()


        payload = ""
        for value in range(1, len(data)):
            if int(data[value]) < 0 or int(data[value]) > 255:
                self._log.warning( + " discarding Tx packet: values out of scope" )
            payload += str(int(data[value]))+","
        payload += data[0] + cmd


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