mb2hal: trying to control a Siemens Sinamics V20 VFD

Hello everyone,

I am new to the forum and to linuxcnc. I am currently trying to connect with a Sinamics VFD using mb2hal.

My setup is a RaspberryPi 4 with the "official" linuxcnc raspibian build with USB to RS485 adapter. This is connected to the VDF using a twisted pair and GND, and all terminating resistors, etc... are connected as recommended by the Operating instructions (attached). I scoped the signals, double, triple checked the parameters set in the VFD. I am 90% sure the communication setup in hardware is sane.

I wrote a very simple .ini file and .hal file to test the communication (attached). The .ini file was written based on the the Operating instructions for number of bits, partiy, etc...

I use to start the hal component. Unfortunately, I get an error message after sending the first command (returned by the VFD if I am not mistaken):
The complete output of the shell command is attached ("shell_mb2hal_output_short.txt"). This is with all debug levels set to 3.

From what I understand, the register addresses are wrongly defined...? I followed the table at page 142 of the Operating Instructions.
Is there something I am missing here?

Also, I noted an error at the beginning:
Which makes no sense to me as transaction 00 is defined and we read two registers. Note that this error is not present for mb2hal.00.01
Again, am I missing something?

I thank you in advance for your insight!

Cheers,

Flawa

Hello,

Apparently the attached pdf was not uploaded. The Operating Instructions can be consulted online at this address :
www.manualslib.com/manual/1203313/Siemen...html?page=142#manual

Cheers,

Flawa

It is possible that the error you see is caised by the earlier error:
Is it possible to fix that? If you insert a line "show pin" straight after the loadrt mb2hal line then you will get a dump of all the pins that exist at that point in the output.

Hi andypugh,

thank you for your answer!

Using , I was able to understand that there is a and pin. Using either of them did get rid of the aforementionned error. So that's a step forward!

Unfortunaltely, the error still shows up. I tried with different register addresses in the range 40000 - 40038 with no success. An example of modbus communication found on the siemens website ( support.industry.siemens.com/cs/document...h-hmi?dti=0&lc=en-US ) seems to confirm that I am using the correct range of addresses.

I will probably factory reset and re-configure, just to be sure.

I am also wondering if there is a precise order in which one needs to access the drive's registers...

Will keep you posted.

Cheers,

Thierry

I think in mb2hal you can turn on a debug mode that shows you the actual data being sent and recieved. That might be helpful to compare with the example modbus communication. So maybe set INIT_DEBUG=3

You might try using 38 (or 37 or 39) instead of 40038 as the element#.

I know the drives I'm using work that way (but they are not Siemens). The documentation lists the addresses as 400XX, but in my config I subract 40,000 from the number. So for address 40008, I'd use FIRST_ELEMENT=8 for 40038, I'd use FIRST_ELEMENT=38.