Siemens CM1241 RS-485 to Prosoft endianness on only some address?

[id10t_error]

Hey Guys, I hope all is well; quick Question,

Background:
We have a Siemens OEM Vendor package we were trying to communicate to, and the processor contains a 6ES7241-1CH32-0XB0 (CM1241 RS-485 communication module) connected to our Prosoft PLX31-EIP-MBS4 (Modbus to EtherNet/IP class1 connection).
We're polling addresses 40001 through 40019 without any communication errors and addresses 40001-40015 contain the correct 16-bit process values from the Prosoft diagnostic window, no problems, and verifiable on the vendors HMI.
However, the endianness seems different in my bit-packed address 40016 through 40019 for boolean statuses and alarms. It's like the lower Byte needs to be swapped with the upper Byte when comparing the current process conditions on the Vendor's HMI to both the Prosoft diagnostic data map and our Vendor's address list in excel.

Question:
If we change the Byte-swapping inside the Prosoft module configuration for just the boolean packed addresses 40016-40019, the Prosoft module throws errors; however, the information seems correct after using an SWBP with REVERSE in studio 5000 to a new tag from our Prosoft Class1 Connection.
What could cause the Vendor's address map to contradict what I see in my Prosoft module other than the list is wrong? Does the CM1241 do something non-standard to the data? I would expect to swap bytes in the whole address range and not just a subset of the bit-packed address.

Let me know your thoughts,
Thanks,

 

[Lare]

It is like that. Integer values are showing same, but packed bits are byte swapped (or reverse order, not sure anymore, allways have tested communincation to get them right) on same words.



1200 and 1500 are actually big endian, but only if optimized db blocks are used.
If you are using non optimized dbs then it is little endian like it was on old 300/400 series.


http://www.plctalk.net/qanda/showthread.php?t=110439

 

[id10t_error]

Lare, Thanks for the help! Do you know where I can find this information in a manual?

Edit:
I'm not used to the siemens website and there's it's somewhat of a learning curve to navigating and platform knowlege.

 

[Lare]

Lare, Thanks for the help! Do you know where I can find this information in a manual?

Edit:
I'm not used to the siemens website and there's it's somewhat of a learning curve to navigating and platform knowlege.

Endianness is something which is well hided for 1200 and 1500.



Your best firend is google for siemens website. It is sometimes hard to find directly with siemens own search on website.


Also try to google Siemens forum posts.



Chartier (probably same than here have allready posted this there)

https://support.industry.siemens.com/tf/ww/en/posts/s7-1200-big-or-little-endian/143030




For 1500 this is newer manual
https://support.industry.siemens.com/cs/ru/en/view/81318674




https://cache.industry.siemens.com/...81318674_Programming_guideline_DOC_v16_en.pdf


For TIA it looks like 1200 is Big endian and only 1500 is little endian if optimized.



Have allways thinked that both would be sameas they are TIA CPUs.


Well, I usally only make quick test with 1200 and projects are with 1500.



I need also to make some test with both 1200 and 1500 and look how bits and bytes actually are used on words.




ps. posted it also yesterday wrongly. Words little and big get mixed.




I should have writed

1500 is actually little endian, but only if optimized db blocks are used.
If you are using non optimized dbs then it is big endian like it was on old 300/400 series.