Separate the properties of a payload so i can send each individual values to another device

[Maxking]

Hi, I am a newbie here, sorry but we all have to start somewhere
Anyway I am not a newbie with BMS (Building Management Systems) also know as BEMS (Building Energy Management Systems).
The BMS control I use (Niagara Tridium N4 controller) has a MQTT pallet which works fine, no issues with sending or receiving MQTT data via my own server MQTT broker.

So my next step is to take a LoRaWan device back into the Tridium Niagara BMS controller.
The LoRaWan device i am using takes MODBUS electric meter network signals and sends the meter values to my LoRaWAN gateway, then I currently send this data to https://www.thethingsnetwork.org/ all fine, no issues.

Now to Node-Red, I take the information for this LoRaWAN device from https://www.thethingsnetwork.org/ into Node-Red and the MQTT in node.

I then create a basic flow which currently sends the data back to the Niagara Tridium N4 controller via MQTT out node, which sends fine and i have added a edit debug node.

Here is the debug data

{"topic":"modbuspowerbar_mcf88/devices/mcf88/up","payload":"{\"app_id\":\"modbuspowerbar_mcf88\",\"dev_id\":\"mcf88\",\"hardware_serial\":\"70B3D58FF1013E38\",\"port\":2,\"counter\":641,\"confirmed\":true,\"payload_raw\":\"CxQAEAABVAaAAasAXQW2AAAAFg==\",\"payload_fields\":{\"CPU_Temp\":34,\"MCB0_Mains\":1.664,\"MCB1_Freezers\":0.427,\"MCB2_Lights\":0.093,\"MCB3_Desk_Sockets_Aircon\":1.462,\"MCB4_Sockets\":0,\"MCB5_Spare\":0.022},\"metadata\":{\"time\":\"2020-08-16T18:04:14.238780126Z\",\"frequency\":868.5,\"modulation\":\"LORA\",\"data_rate\":\"SF7BW125\",\"airtime\":71936000,\"coding_rate\":\"4/5\",\"gateways\":[{\"gtw_id\":\"eui-60c5a8fffe766204\",\"timestamp\":1490131788,\"time\":\"\",\"channel\":7,\"rssi\":-43,\"snr\":8.5,\"rf_chain\":0,\"latitude\":51.88843,\"longitude\":-0.53416,\"altitude\":148}],\"latitude\":51.888424,\"longitude\":-0.53416693,\"altitude\":148,\"location_source\":\"registry\"}}","qos":0,"retain":false,"_msgid":"27e905e3.3f2b4a"}

Now what i would like to do is separate the payload_fields, so i can send each individual field to the Niagara Tridium controller.

{\"CPU_Temp\":34,\"MCB0_Mains\":1.664,\"MCB1_Freezers\":0.427,\"MCB2_Lights\":0.093,\"MCB3_Desk_Sockets_Aircon\":1.462,\"MCB4_Sockets\":0,\"MCB5_Spare\":0.022}

I have looked through the forum, and see detailed information on the topic using a change node and a switch node, but not getting very far, so any help would be appreciated.

Below is the current input into the Tridium Niagara controller, which is a long string input.

Any ideas for the best way to extract the 7 fields in the payload ?

Thanks for reading.

[Steve-Mcl]

@Maxking

Here is the debug data

Now what i would like to do is separate the payload_fields

So a small lesson on JS objects and their equivalent string representation (AKA JSON)...

Your payload is a string/JSON (due to the Output setting on the MQTT node). You could attempt some complex splits and loops etc - but - as it is JSON (JavaScript Object Notation) - just let JS do its thing - turn that JSON back into a JS Object! (if you dont know what I mean, it'd be worth reading up - will help you greatly in node-red knowing the difference)

So first off, change that MQTT IN to...

Now, you data will be an actual JS object (not a string / not JSON)...

And once its an object, you can simply "copy path" of any item in the object & use that in a change node (or whatever)...

So, from that, you could generate new messages by using parallel change nodes...

ending up with this...

my demo flow...

[{"id":"635795b0.ebc5dc","type":"inject","z":"485b32f3.0bdfbc","name":"your MQTT IN data (faking it)","topic":"modbuspowerbar_mcf88/devices/mcf88/up","payload":"{\"app_id\":\"modbuspowerbar_mcf88\",\"dev_id\":\"mcf88\",\"hardware_serial\":\"70B3D58FF1013E38\",\"port\":2,\"counter\":641,\"confirmed\":true,\"payload_raw\":\"CxQAEAABVAaAAasAXQW2AAAAFg==\",\"payload_fields\":{\"CPU_Temp\":34,\"MCB0_Mains\":1.664,\"MCB1_Freezers\":0.427,\"MCB2_Lights\":0.093,\"MCB3_Desk_Sockets_Aircon\":1.462,\"MCB4_Sockets\":0,\"MCB5_Spare\":0.022},\"metadata\":{\"time\":\"2020-08-16T18:04:14.238780126Z\",\"frequency\":868.5,\"modulation\":\"LORA\",\"data_rate\":\"SF7BW125\",\"airtime\":71936000,\"coding_rate\":\"4/5\",\"gateways\":[{\"gtw_id\":\"eui-60c5a8fffe766204\",\"timestamp\":1490131788,\"time\":\"\",\"channel\":7,\"rssi\":-43,\"snr\":8.5,\"rf_chain\":0,\"latitude\":51.88843,\"longitude\":-0.53416,\"altitude\":148}],\"latitude\":51.888424,\"longitude\":-0.53416693,\"altitude\":148,\"location_source\":\"registry\"}}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":180,"y":140,"wires":[["cfe3cfe5.2fd24","d7eb57a2.3aa148","6d3aae76.88f9"]]},{"id":"362f42bb.e4a57e","type":"debug","z":"485b32f3.0bdfbc","name":"to MQTT Out node (or whatever)","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":690,"y":140,"wires":[]},{"id":"cfe3cfe5.2fd24","type":"change","z":"485b32f3.0bdfbc","name":"CPU_Temp","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload.payload_fields.CPU_Temp","tot":"msg"},{"t":"set","p":"topic","pt":"msg","to":"modbuspowerbar_mcf88/devices/mcf88/up/CPU_Temp","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":410,"y":140,"wires":[["362f42bb.e4a57e"]]},{"id":"d7eb57a2.3aa148","type":"change","z":"485b32f3.0bdfbc","name":"MCB0_Mains","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload.payload_fields.MCB0_Mains","tot":"msg"},{"t":"set","p":"topic","pt":"msg","to":"modbuspowerbar_mcf88/devices/mcf88/up/MCB0_Mains","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":420,"y":200,"wires":[["362f42bb.e4a57e"]]},{"id":"6d3aae76.88f9","type":"change","z":"485b32f3.0bdfbc","name":"MCB1_Freezers","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload.payload_fields.MCB1_Freezers","tot":"msg"},{"t":"set","p":"topic","pt":"msg","to":"modbuspowerbar_mcf88/devices/mcf88/up/MCB1_Freezers","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":420,"y":260,"wires":[["362f42bb.e4a57e"]]}]

EDIT...

I updated your threads topic as it was fairly inconsequential to do with what you were trying to achieve. In fact, I skipped over your question earlier as I had no clue what a "Niagara Tridium N4 controller" was & thought I couldn't help you (likely others did too). My point is, try to title your topics in relation to the goal or issue.

[Maxking]

Thank you so much Steve, that worked great and the data is now exported to the Building Management system

Thank you again for the quick answer back.

BMS Controller with MQTT inputs