How to split a long message and filter for information

General
1

Hi,
I'm quite new in working with node red. I got this following message from a Victron Batterie Monitor (BMV 712) and I would like to get some of the data in an InfluxDB.
I use the node VE.direct USB triggered by a timestamp and parse it with the json node.
How can I convert this data in something the InfluxDB can work with?

{
"PID": {
"value": "0xA383",
"description": "ProductID",
"units": "",
"product": "BMV-712 Smart Rev2"
},
"V": {
"value": 26479,
"description": "Main or channel 1 (battery) voltage",
"units": "mV"
},
"T": {
"value": 20,
"description": "Battery temperature",
"units": "°C"
},
"I": {
"value": 0,
"description": "Main or channel 1 battery current",
"units": "mA"
},
"P": {
"value": 0,
"description": "Instantaneous power",
"units": "W"
},
"CE": {
"value": -1305,
"description": "Consumed Amp Hours",
"units": "mAh"
},
"SOC": {
"value": 998,
"description": "State-of-charge",
"units": "‰"
},
"TTG": {
"value": -1,
"description": "Time-to-go",
"units": "Minutes"
},
"Alarm": {
"value": "OFF",
"description": "Alarm condit…

Thanks a lot in advance.

2

Welcome to the forum @Emmi

Do you know exactly what form you want the data in?

If not then which version of influxdb are you using and do you know what measurements, fields and tags you want?

3

Hi,
thanks for the fast response. I use InfluxDB v2.8.0. Looks like I copied the wrong output (I tried a lot before asking you)
This is what the json node gives me:

{"PID":{"value":"0xA383","description":"ProductID","units":"","product":"BMV-712 Smart Rev2"},"V":{"value":27517,"description":"Main or channel 1 (battery) voltage","units":"mV"},"T":{"value":23,"description":"Battery temperature","units":"°C"},"I":{"value":-181,"description":"Main or channel 1 battery current","units":"mA"},"P":{"value":-5,"description":"Instantaneous power","units":"W"},"CE":{"value":-6171,"description":"Consumed Amp Hours","units":"mAh"},"SOC":{"value":994,"description":"State-of-charge","units":"‰"},"TTG":{"value":14400,"description":"Time-to-go","units":"Minutes"},"Alarm":{"value":"OFF","description":"Alarm condition active","units":""},"Relay":{"value":"OFF","description":"Relay state","units":""},"AR":{"value":0,"description":"Alarm reason","units":""},"BMV":{"value":712,"description":"Model description (deprecated)","units":""},"FW":{"value":419,"description":"Firmware version (16 bit)","units":""},"MON":{"value":0,"description":"DC monitor mode","units":""},"H...

First I would like to have the basic values: Voltage, Temperature, Current
and the status of the Alarm also would be nice.

4

This is a suggestion I got from ChatGPT for some JavaScript in function node to process your JSON before sending it to an InfluxDB node. I'm assuming your message is in msg.payload

let d = msg.payload;

msg.payload = {
    measurement: "bmv712",

    tags: {
        PID: d.PID.value,
        product: d.PID.product
    },

    fields: {
        V_mV: d.V.value,
        T_C: d.T.value,
        I_mA: d.I.value,
        P_W: d.P.value,
        CE_mAh: d.CE.value,
        SOC_permille: d.SOC.value,
        TTG_min: d.TTG.value,

        Alarm: d.Alarm.value,
        Relay: d.Relay.value,

        AR: d.AR.value,
        BMV: d.BMV.value,
        FW: d.FW.value,
        MON: d.MON.value
    }
};

return msg;

You can edit/delete the 'fields' as necessary.

5

What do you see before the JSON node?

6

msg.payload : Object

object

PID: object

value: "0xA383"

description: "ProductID"

units: ""

product: "BMV-712 Smart Rev2"

V: object

value: 26500

description: "Main or channel 1 (battery) voltage"

units: "mV"

T: object

value: 21

description: "Battery temperature"

units: "°C"

I: object

value: 207

description: "Main or channel 1 battery current"

units: "mA"

P: object

value: 5

description: "Instantaneous power"

units: "W"

CE: object

value: -1424

description: "Consumed Amp Hours"

units: "mAh"

SOC: object

value: 997

description: "State-of-charge"

units: "‰"

TTG: object

value: -1

description: "Time-to-go"

units: "Minutes"

Alarm: object

value: "OFF"

description: "Alarm condition active"

units: ""

Relay: object

value: "OFF"

description: "Relay state"

units: ""

AR: object

value: 0

description: "Alarm reason"

units: ""

BMV: object

value: 712

description: "Model description (deprecated)"

units: ""

FW: object

MON: object

H1: object

H2: object

H3: object

H4: object

H5: object

H6: object

H7: object

H8: object

H9: object

H10: object

H11: object

H12: object

H15: object

H16: object

H17: object

H18: object

7

this script gives me an error:
{"enc":true,"type":"error","data":{"name":"TypeError","message":"Cannot read properties of undefined (reading 'value')","stack":"TypeError: Cannot read properties of undefined (reading 'value')\n at Function node:16998054156cc482 [function 3]:8:20\n at Function node:16998054156cc482 [function 3]:32:3\n at Script.runInContext (node:vm:149:12)\n at processMessage (/usr/lib/node_modules/node-red/node_modules/@node-red/nodes/core/function/10-function.js:430:37)\n at FunctionNode._inputCallback (/usr/lib/node_modules/node-red/node_modules/@node-red/nodes/core/function/10-function.js:348:17)\n at /usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/nodes/Node.js:214:26\n at Object.trigger (/usr/lib/node_modules/node-red/node_modules/@node-red/util/lib/hooks.js:166:13)\n at Node._emitInput (/usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/nodes/Node.js:206:11)\n at Node.emit (/usr/lib/node_modules/node-red/node_modules/@node-red/runtime/lib/nodes/Node.js:190:25)"}}

8

It means somewhere in your Function node you are doing something like:

something.value

…but something is undefined at runtime.

Probably best to delete the fields or double-check the names match what is in function node.

9

Your data is already a JavaScript object, the json node is converting it to a string, which you don't want. Take out the json node.

10

grafik
grafik1669×779 82.4 KB

You are right the output (in Influx) looks the same without the json node. But Influx still does not split the values.