Extract sensor values in Node-red

[gohan]

https://www.mysensors.org/build/mqtt_gateway

it is pretty much the same as the ethernet, it just needs a few extra parameters and an mqtt broker running somewhere (if you already have a RPI, just install mosquitto)

[lozzer65]

@gohan Ok, thanks for the advise. Strange that I can't use what I have, especially seeing as I can see the data coming from the sensors in node-red.

[gohan]

I don't remember how to use the mysensors nodes, but knowing how mqtt works, just take advantage of it: the sensor is publishing a value to a topic, so just read that.

[lozzer65]

@gohan I am just thinking about the implications of moving to mqqt. This will break my home assistant setup. I also have over 30 sensors I would have to change the setup of.

If you see this as an example, "67;0;1;0;0;62.5↵" which is my data from a sensor showing in node-red debug. The 67 is the nodeId, the next 0 is the childSensor Id and the 62.5 is the temperature.

This the code I am using in a function of node-red to try and extract the temp value.
if (msg.payload.nodeId == 67 && msg.payload.childSensorId === 0) {
var msg;
msg.payload = msg.payload.value;
msg.topic = "Temperature";
return msg;
}

Can anyone spot any reason why this may not work ?

[gohan]

You don't need to change the sensors. Did you check if HA doesn't support mqtt gateway?

[lozzer65]

I have built an Mqtt gateway as you suggested. from the arduino serial monitor I can see it working, as below.
0;255;3;0;9;Sending message on topic: mygateway1-out/67/3/1/0/0
0;255;3;0;9;TSF:MSG:READ,67-67-0,s=3,c=1,t=0,pt=7,l=5,sg=0:11.5
0;255;3;0;9;Sending message on topic: mygateway1-out/67/3/1/0/0
0;255;3;0;9;TSF:MSG:READ,67-67-0,s=3,c=1,t=0,pt=7,l=5,sg=0:11.0
0;255;3;0;9;Sending message on topic: mygateway1-out/67/3/1/0/0
0;255;3;0;9;TSF:MSG:READ,67-67-0,s=3,c=1,t=0,pt=7,l=5,sg=0:11.5
0;255;3;0;9;Sending message on topic: mygateway1-out/67/3/1/0/0
0;255;3;0;9;TSF:MSG:READ,67-67-0,s=3,c=1,t=0,pt=7,l=5,sg=0:11.0
0;255;3;0;9;Sending message on topic: mygateway1-out/67/3/1/0/0
0;255;3;0;9;TSF:MSG:READ,67-67-0,s=5,c=1,t=0,ptto=7,l=5,sg=0:16.5
0;255;3;0;9;Sending message on topic: mygateway1-out/67/5/1/0/0

I have mosquitto broker running on my pi 3. Node-red shows connected to the mqqt broker, yet no data is shown passing.

any ideas how best to fault find this issue

[gohan]

If you use a mqtt client and subscribe to the topic mygateway1-out/67/5/1/0/0 do you actually see messages? Or subscribe to mygateway1-out/# and see all mqtt messages. If you see correct messages your setup is correct

[lozzer65]

Gohan

Thanks very much for that pointer. You have been very helpful. All working now.

[gohan]

Do you think it is easier with mqtt or with serial?

[tbowmo]

If you use the node-red-contrib-mysensors nodes, then you can split the sensor string into the different parts.

Then you are able to use for example the switch node, to filter the data..

[Geoff]

@lozzer65 I'm playing with node red and a mock TCP gateway at the moment and looking at your code I think the problem is that rather than msg.payload.nodeId it should be msg.nodeId and msg.payload.childSensorId should be msg.childSensorId. I realise you've moved on to MQTT but thought I'd mention it in case others come looking.

[scottdube]

@tbowmo Hi there I have your nodes installed but having a little trouble getting started. Is there any documentation I could follow? I want to build a flow just like the one you have in this post. Thank for your help and your work on this!

[tbowmo]

@scottdube

Sorry I don't have more documentation at hand, than what is in the mysensors npm module already. But basically I use the switch node to route messages, on subtype, then on nodeId, and last on childId.

I'm currently remodeling my node-red setup.. Moving everything to MQTT for internal message distribution between all parts (both within node-red and to external systems).

[scottdube]

@tbowmo Thank you, would it be possible to get that flow? I have not been successful building it myself.

Thanks for your work on this!

[tbowmo]

@scottdube

I have put my nodered flows on github as a project, where you can clone from, find it at https://github.com/tbowmo/nodered-mysensors-flow

Please note that this is taylored specifically to my usage, but could be used as an inspiration..

(In nodered 0.18.x they have added possibility to have multiple projects, including git and github integration)

[scottdube]

@tbowmo Thank you! I am needing the inspiration! :)