Why does my A to D hang sometimes?

[Kendrick]

I have been using a VXIpc-850 (200 MHz) controller and a VM2616 DAC with good success.  Now I switched to a VXIpc-872B (1.26 GHz) controller and I get a hang sometimes when I do an instrument write.  Here is the process I use: 1. Reset instrument, set voltage range and triggering.  2. Send data to instrument.  3. Write to instrument with following string: STAT:OPER:COND?.  4. Read instrument.  5. Write to instrument with the following string: REG:ADDR 0,(@1).  Most of the time it hangs at the first write (STAT:OPER:COND?), sometimes it hangs at the reset, sometimes it hangs at the last write, sometimes it proceeds without errors and gives me the data I expect.  I updated the drivers and added delays in various places to account for the faster processor but I suspect there is something else.

Does anybody have any clues?

Kendrick Krause

PS. That is supposed to be STAT colon OPER:COND?.  It is interpreting the colon O as a smiley face.

[John E]

Hi Kendrick,
One thing you may want to try is verifying that the program still works on the old controller, this will verify that no issue has crept up with the cabling or the instruments.  In addition as you already referenced, the speed increase may be causing issues.  You may want to increase wait times throughout the code very significantly, just to see if that resolves the issue.  Then you can further refine the search by reducing the wait times.


Regards,

[Kendrick]

Hello John,

THANKS for the response.

I have tried adding delays up to 1 full second and boolean indicators all over the place to track the flow.

Still works with the other controller.

Ooops, forgot to mention that old controller and code is LV 5.1 - Win'98, new controller and code is LV 7.1 - WinXP. (yes, re-compiled)

Still, I don't suspect the code because of the "somtimes it hangs".

I can run it over and over several times with no problem, then... stuck.

70% of the time it hangs at the first write the other 30% is spread between Reset, the second Write and Read, once it hung on a config.

I haven't given up adding delays, I'll dig deeper but the system and its software are not mine.

Will keep you posted, unless you or somone else has any other ideas.

Thanks,

Kendrick