CompactRIO RT freeze when I use "Set Time.vi"

[Nicolas Bats]

Hi everyone,

 

I'm using a compactRIO and need to update the internal time of the device to be clock synchronized with my whole system. Everything seemed to work perfectly but when I try to apply an offset between 0 and -30 seconds, my compactRIO freeze. Nothing happen if I apply a positive offset or an offset "higher" (in a negative way) than -30 sec.

 

The duration of the freeze equals the offset I apply on my device and after this delay, everything comes back to normal. The freeze affects all my RT code (other processus as well) and not only the VI where I use the "Set Time.vi". The FPGA seems to be working during the freeze time because I got "DMA is full" error after the freeze and some LEDs keep blinking during the whole time.

 

Has any of you already noted something similar on compactRIO 9068 (Linux) ? Or do you have any idea of what is going on ?

 

Thanks for you help.

Nicolas

 

Additionnal informations :

   - LabVIEW 2013 SP1

   - NI RIO 14.0.1

   - CompactRIO 9068

   - Linux Embedded

   - LavBIEW Real-Time 13.0.1

Edited July 30, 2015 by azerty

[smithd]

Are you using timed loops with the time source set to absolute time? Since the loop is tied to absolute time I've seen this cause issues when the system time is modified.

Do regular while loops freeze too?

How are you determining that things have frozen? Are you running in interactive mode? If so, does it disconnect when you trigger this change?

Are there any other sections of your code where you are changing behavior based on a timestamp?

[Nicolas Bats]

Hi smithd,

 

Are you using timed loops with the time source set to absolute time? Since the loop is tied to absolute time I've seen this cause issues when the system time is modified.

 

Off course not. I was using simple "Tick Count.vi" or "Wait.vi" but the problem occures even without any timing function.

 

Do regular while loops freeze too?

 

Yes.

 

How are you determining that things have frozen? Are you running in interactive mode? If so, does it disconnect when you trigger this change?

 

I'm using the compactRIO in interactive mode yes but it also happen with an rtexe.

 

I make the RT LED blink every 200ms and the LED stop blinking during the freeze, then blink again.

 

No the compactRIO stay connected during the freeze.

 

Are there any other sections of your code where you are changing behavior based on a timestamp?

 

Only one process changes the timestamp of the compactRIO and several processes are based on this timestamp. But this is not a problem because I detect internal clock modifications and inhibit any malfunction related to this modification.

Edited July 31, 2015 by azerty

[Nicolas Bats]

Here is an example if it can help.

 

[Nicolas Bats]

After many tests, using LabVIEW 2014 & NI Real Time 14.0.1 seems to "solve" the issue.

 

I don't have informations or explanations about the behavior described above, but I will update this topic if I got somes from NI. Meanwhile, Linux compactRIO users should consider to use NI RT 14.0.1 instead of 13.0.1.