BYTE order in ModBus

[TomasAdvance]

Hi Frangoteam,
Are they some posibility to define byte order in ModBus TCP for int32?
Thnaks for your answer.
We are connected to WAGO PLC 750-891, and if I understand the wago correctly the byte order for int32 is BADC. Is it any possibility to define byte order in fuxa scada system for int32 variable on modbus tcp?
Tomas

[unocelli]

Hi,
if you mean little-endian...yes

[TomasAdvance]

Hi, no I mean swapping bytes.
Example if you have bytes A B C D, with big and little endian you swap two bytes lite that D C B A. But if you want order like that C D A B?How can be done in Fuxa? Or it should be new feature.
I hope it is more clear
T

[TomasAdvance]

Hi,
Any idea how to do it?

[TomasAdvance]

Hi,
I found more explanation about what I try to explained.
Could be topic for implement following byte order for 32bit:

Float - Big Endian (ABCD) - currently implemented

Float - Little Endian (DCBA) - currently implemented

Float - Mid-Big Endian (BADC) - not implemented yet

Float - Mid-Little Endian (CDAB) - not implemented yet

Similar is fot another data type.

What do you thinking about?
Thanks

[unocelli]

Hi,
the request seems a bit specific, in which case you use this Mid datatype?
I don't think that the library used modbus-serial support this format.

[TomasAdvance]

This specific byte order I have got with wago controller. It is incredibly think.
But now way how to change it.
Can be implemented that byte order as I mentioned above?
BR

[unocelli]

We can try...I created the modbus/wago branch, as a first test to see the applicability I added the type Float32MBE can you test it?
Thanks

[TomasAdvance]

Hi,
I will test it of course.
Let me know when you release it.
T

[TomasAdvance]

Hi,
Any news about this topic?

[unocelli]

I would appreciate it if you could do a test with the modbus/wago branch and the new type Float32MBE. so that I can understand that I am on the right way. I don't put changes in a release if we haven't tested them before.

[TomasAdvance]

Hi,  I try to test with new code (I downloaded latest working version of code from git) but I can find that ne capability. Can you help me whera I can find it?  BR Tomáš  Tomáš Pastrňák 

…

________________________________ Od: Umberto Nocelli ***@***.***> Odesláno: středa 23. března 2022 21:02 Komu: frangoteam/FUXA Kopie: TomasAdvance; Author Předmět: Re: [frangoteam/FUXA] BYTE order in ModBus (Discussion #275) I would appreciate it if you could do a test with the modbus/wago branch and the new type Float32MBE. so that I can understand that I am on the right way. I don't put changes in a release if we haven't tested them before. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.Message ID: ***@***.***>

[unocelli]

You have to download and install the modbus/wago branch (not from master) and then you should be able to configure tag of type Float32MBE

[TomasAdvance]

Hi I try to test it but during installation I have got following errors? Any idea what can happen?
BR
Tomas

If I ignore above error and start FUXA, Modbus TCP connection not working, no data receiving.

[unocelli]

are warnings, you can ignore them. have you installed the plugin?

[TomasAdvance]

Hi, I have solved it, Python installation was missing in that computer. Now is working

[TomasAdvance]

Hi,
I have test it, but result is wrong as you can see in printscreen
First value must be around 230VAC and third value around 50Hz.

I am able to provide remote access to this station if will be helpful.
Let me know
Tomas

[unocelli]

😕
can you tell me the value of the 4 bytes on the wago plc?

[TomasAdvance]

Hi, I make new print screen where you can see all about. Transformed value in MBpoll 1, raw data in bytes in MB poll 2.

For correct transformation is Little-Endian byte swap used.

[unocelli]

Thank you very much, the screenshots are very helpful, I will try again tomorrow.

[TomasAdvance]

ok,
As I said, if you want to have remote access to station, let me know I will arrange it.
Tomas

[unocelli]

Hi,
I make a change in datatypes, you have to unzip and copy the js file in \server\runtime\devices\modbus\ and restart the server
datatypes.zip

[TomasAdvance]

Hi,
it is working very well, you can see in print screen

Please change only, the name Float32MBE to Float32MLE (Float - Mid-Little Endian) that is correct name of byte order.
Excelent work

[unocelli]

Great, I will change the name...there is only the float32 to swap? If no how I have to swap the other one?

[TomasAdvance]

It is valid for all 32 byte data type. Byte order will be same as we have in Float32. Most common will be Int and Uint data type.
Tomas

[unocelli]

I merged into the master branch, you have to reconfigure the tag with the new type name. Thanks a lot

[TomasAdvance]

ok, thanks as well
T