Mix up of MSB / LSB

[martinste1n]

Hi,

configured a Device with the following setting:
Byte order: MSB
Register Order: R0R1R2R3

see here:

When adding an item (UDec16; value 4) to a holding register and reading it using a java client the bytes I recieve is [4,0] instead of [0,4].

When changing the ByteOrder to LSB it is the other way around. I think the UI need to switch the labels.

My environment:

Ubuntu 24.04
ModbusTools Version: 0.4.8

Thanks for the great work!

Martin

[serhmarch]

Hello.

Maybe it is a bit confusing but this setting (Byte Order) is related to data display order (as well as Register Order), not for data transfer order.

It is like post processing setting, because Modbus protocol clearly specifies that the MS byte is transmitted first, followed by the LSB.

So the normal value is Less Signified First. In this case, data transfer occurs as expected.