MODBUS 16bit SIGNED INTEGER

General
1

Hello.
I'm reading MODBUS holding registers.
On register 0 the value is -35 (signed).
If I show this value in gage the value is 65501 (unsigned).
How can I show SIGNED INTEGER?
Thanks.
BR.

1 Like
3

What do you get coming out of whatever node you are using for modbus? Feed it directly into a debug node and screenshot please.

4

Modbus
Modbus220Ă—527 7.65 KB

5

is that directly from the MODBUS node?

Some of the modbus nodes output a buffer object.

And if it is a buffer then its pretty simple : in a function node (untested)...

let buf = msg.payload;
msg.converted = [];
msg.converted[0] = buf.readInt16BE();
msg.converted[1] = buf.readInt16BE();
msg.converted[2] = buf.readInt16BE();
//... etc ...
return msg;

see buffer documentation for a whole raft of read functions (for when you ask how to read floats next :wink: )

6

To use the data as in the debug then you can do, for each item in the array
msg.payload[i] = (msg.payload[i] << 16) >> 16

1 Like
7

Collin you are the best.
Simple and effective sollution.
BR.

8

Collin.
Off topic question.
Do you have similar (simple) idea of how to show BCD formated numbers?
I have posted: OMRON BCD format
Thanks.
BR.

9

Ask for further help on that thread. One poster described how to do it, if that is not in sufficient detail then ask for further clarification.

10

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