Separate time stamp and payload from string

General
1

Hello
I working on power and some other sensor monitoring application
My device is sending value via MQTT with a timestamp,
something like this -- 12:38:18:128.79 where {12:38:18} is a timestamp and {128.79} is a value which needs to show in a simple chart
Now can someone please help me in how to separate those to value and shown in the chart

image
image1920×1080 231 KB

I am just beginner in Nod red and with basic knowledge of programming.
Ans in little detail appreciated

Thanks in advance

2

Welcome! Your device is sending not so “well” formatted messages but never mind.

You can use a function node using the string.split() function and take your string appart:

var parts=msg.payload.split(“:”);
msg.timeString=parts[0]+”:”+parts[1]+”:”+parts [2];
msg.payload=Number(parts[3]);
msg.timestamp= new Date();
msg.timestamp=msg.timestamp.setHours(Number(parts[0]), Number(parts[1]), Number(parts[2])).valueOf();
return msg;

Code not tested just typed in on my phone but give it a try.

3

Thanks a lot, brother !!
For as of now i have solved issue using substring method some thing like this
var value = msg.payload;
value = value.substring(9,14);
return {payload:value};

and your code is very used full to use the timestamp from payload itself!

4

But be careful if your timestamp comes without leading zeros like “9:10:11”

var parts=msg.payload.split(“:”);
msg.payload=Number(parts[3]);
return msg;

Or even more safe

var parts=msg.payload.split(“:”);
msg.payload=Number(parts[parts.length-1]);
return msg;

Then even “5:40:123.45” will work.