Multiprocessing with ul.a_in_scan()

[LostPhysicist]

Hello, 

i would like to use multiple daq-crads which run in parallel in  analog scan mode/analog output. And for simplicity of the programm  i thought that i just run the ul.a_in_scan with multiprocessing. The problem now is that in the individual processes the memhandle i reserved with ul.scaled_win_buf_alloc(total_count) seems to be invalid (so it says in the errorcode: mcculw.ul.ULError: Error 35: Pointer is not valid.). 

In the singel card programm i wrote for just one cards use with out any parallelizing it works quit well. 

Are there some limitation with ul.libary refered to parallelizing. I even tried a lock but it doesnt work. Or has any one experience with multiprocessing with the ul.libary 

 

Thanks for your help in advance 

 

 

 

input_mulitcrads_inprogress.py

Edited December 24, 2023 by LostPhysicist

[Fausto]

Hello @LostPhysicist.

Using a MCC USB-231 and USB-234 along with your Python example, I am unable to reproduce the errorcode: mcculw.ul.ULError: Error 35: Pointer is not valid.  Which MCC daq devices are you using?

Which versions of Windows OS, InstaCal, and mcculw are you using?

Please provide additional information to help troubleshoot your issue.

Regards,

Fausto

[LostPhysicist]

Hi, 

I am using the MCC USB-1208HS-4AO

curruntly  i am using windows 10 Pro 

instacal: 6.74.. but curruntly i am creating the daq with the python comand 

mcculw: 1.0.0

 

And my script worked with your devices and settings so far ? 

Kind regrads 

 

 

[LostPhysicist]

Most interesting, 

i just tried the same script again on two MCC USB-1208HS-4AO, same PC... as before and now the ''Error 1: invalid Boardnumber ''occurs. If I change the second board number  to 0 aswell the error 1 vanishes  and the ''Error 22: Background operation already in progress'' ocurrs, whiche is plausible, since i have overwriten boardnum 1 with 0 too. But why is 1 not valid in the first place. 

 

Thanks for your help. 

Kind Regards