Buffer parser node "LSW / MSW"

General
1

Hi,
I found this closed, unsolved topic: https://discourse.nodered.org/t/going-crazy-trying-to-read-signed-int32-from-buffer
as I want to parse data from the same device. The problem is that it is providing int32 data as "LSW / MSW" (Least significant word first) eq. 0xabcd as 0xcdab. Is there anyway to parse this data within the buffer parser node?

2

Yes. Use the swap32 option.

3

You can directly choose if you want (le) or (be).

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4

Thank you for your quick answers. Big endian and little endian refers only to the bits inside a byte (LSB / MSB). The solution to my issue was the Byte swap feature. I set Byte swap to Swap 16 and now it's correctly parsed.
Have a nice day!

5

AFAIK Little indian/big indian has always referred to the order of bytes within a multibyte integer and has never been used as a description of internal bits in a byte.

I've never seen a byte where the bits are the "wrong" way around :slight_smile:

1 Like
6

You are both correct, however when talking about endian as bits inside a byte that is typically called bit-endianess & is often only at communication level (not architecture level)

Good write up here: Endianness - Wikipedia

2 Likes
7

Thanks for your comments. In the buffer parser node it looks like to be as follows:

  • the variable type "int32 be" and "int32 le" parses 0xabcd or 0xdcba
  • the byte swap 16 for the same value parses 0xabcd as 0xcdab

That's why the manufacturer of this device speaks from LSW / MSW as a "Word" is two Bytes.

8

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