Extract sensor values in Node-red

[gohan]

@lozzer65 have you tried the mysensors nodes?

[lozzer65]

Hi
Yes I have. They just seem to to reformat the whole data. I just want to extract the temp value from each sensor to display in a gauge and a graph.

[gohan]

Are you using mqtt gateway or ethernet?

[lozzer65]

@gohan Ethernet gateway. As you can see above I have data. Just can't seem to extract the temp value for each sensor to make it usable for a gauge and graph

[gohan]

If you switch to mqtt gateway, you could just link the gauge to the topic of the sensor and you are done

[lozzer65]

@gohan Hi, Can you give me some pointers on what I need to do to change to MQQT Gateway. I am not overly sure on the difference.

[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!