Modbus 16bit words to doubleword problems

General
1

Hi Everyone,

I'm having problems converting modbus word registers (16 bits) to double (32 bits) format.
Modbus RTU Buffered using node-red-contrib-modbus (4.1.3)

I've tryed to use this (Buffer) in a function but it's not working fine:
let VL1= msg.payload.buffer.readDoubleLE(0,2)
Trying with BE and LE and it's not working fine. I think that with that buffer instruction it tooks 4 modbus words (4x 16bits)...

I don't know how to do it.
Sometimes in other technologies like industrial PLC's i've used SHL (shift left), and other options to do that.
In that ocasion I can't find the correct way to do it.

Can you help me please with it?

Thanks in advance

2

Hello again,

Changing readDoubleBE with readInt32BE I'm getting some values right (not all).
Working with it.

3

Hello again,

No way
:dizzy_face:

Someone knows how to do it?

Thanks

4

Just do it yourself.

Use JavaScript bitshift operators.

Try shifting 1 word 16 bits then add it to the next word.

1 Like
5

Thanks @Steve-Mcl,

It's working.
I've tested this before, but mybe with some typing errors because the result was NaN.

Thanks!!

1 Like