NI-CAN 8512 Change to PCI and then Machine cycle time add 1 second

[nexteer_LZ]

Hello,

Test machine 's card 8512 was change to PCI, the application still the same, but machine cycle time add 1 second.   Could you please give us some advice why this happen? Thank you very much!

Best regard,

Brian

[nexteer_LZ]

Add screenshots of CAN communication vi.

And learn from one of my colleagua that PCI card need to use XNET program, it is ture?  We don't know how to use XNET to write new program , so that we can NOT verify this way.

[JefeL]

Can you clarify what the original hardware was that the 8512 replaced? Was it a NI-CAN based device with a name like PCI-CAN? Or did you replace a PCI-8512 with a new PCI-8512?

The PCI-8512 does use the NI-XNET driver. The NI-XNET driver also includes a library that can be installed which allows most older NI-CAN based applications to  run on XNET hardware. This library is called the XNET Compatibility Library and is likely already installed or the PCI-8512 wouldn't show up as a NI-CAN device in MAX.

Can you tell me more about the problem with cycle time? Are you talking about the cycle time of an operation or the cyclic rate of a specific frame etc? Can you give me more context about this extra second? How long was an entire cycle with the old hardware? The more descriptive you can be about the previous working state versus the current behavior the more helpful my answers can be.

[nexteer_LZ]

Hi Jeff,

Thanks for your reply.

The original hardware was PCI-8512#780683-01, and we replaced this card with PCI-CAN#777357-01 now

Cycle time begin at new test and end at the test finish.

 PCI-8512#780683-01 cycle time is 16.2s, PCI-CAN#777357-01 cycle time is 17.2S;

Once you change PCI-CAN#777357-01 back to  PCI-8512#780683-01 , and then cycle time change back to 16.2s too, application is the same.

Best regard,

Shufa

[Minions]

I am not familiar with these cards.  Do you need to set the series resistance on the PCI-CAN to 120-ohms?  It may be that it is having errors during the transmission which are being automatically re-sent causing this additional delay.

[nexteer_LZ]

Hello,

We will check the resistance laster.

If we rewirte the application with  XNET vi to replace the old CAN.vi, Does it will affect the cycle time?

Thanks!

Best regards,

Brian Qin

[JefeL]

Applications written with the XNET API will be more performant than applications written in NI-CAN that have to go through a conversion library. That being said, we don't have enough information to say if code execution performance is the root cause of the extended cycle time. It could very well be termination as previously suggested by Minions. I would suggest verifying termination is being set properly as a first step.

You can also use the XNET bus monitor in subordinate mode to monitor the activity on the bus. Enable the bus error frames option to see if error frames are being detected. This would quickly suggest that termination is a problem.