Real-Time Measurement and Control

[rustawilliams]

Hello,

I am currently having trouble getting any response from the spline trajectory generator in order to feed a contoured profile from my RT code through to the FPGA of my compactRIO system. I write the points to the contour buffer, start the motion and there is no response from my trajectory loop.

Attached is the RT code for the system and a couple of screenshots from my debugging. I am using LabVIEW 2011. I have used a set posted on this site to bring back the older trajectory generation function as my hardware does not work with the scan engine.

Thanks for help in advance,

Rhys

[NateBraska]

Hi Rhys,

That is interesting. What does the status say for the "Status" in your second screen shot? Is the move still active?

I see that you are using the trajectory generation functions since you cannot use scan engine, but is there a reason you are not using the Axis Interface API instead of the Trajectory Generator API? This KnowledgeBase article talks about migrating to the Axis Interface API.

Best Regards,

Nathan B

Applications Engineer

National Instruments

[rustawilliams]

Hi Nathan,

I have intended to move towards the new functions but I'm pretty unsure whether my system would work with them. On the page you linked, there is a line 'The RT target must support the NI Scan Engine to use the Axis Interface API.' which seems to rule that out. Are you able to point to examples/tutorials/web pages which detail a method of doing a contoured move using a compactRIO with a PID and position setpoint updates in the FPGA loop which doesn't require the Scan Engine?

Thanks,

Rhys

[Ben-N]

Hi Rhys,

Based on the debugging you posted, it sounds like your FPGA program may not be running at all.  Have you tried debugging the FPGA program?  Is the bitfile deployed to the FPGA on your chassis?  Because your spline data is continuously returning a cluster of zeros, it leads me to believe that something is wrong with the FPGA VI. Have you tried running the the FPGA VI interactively with indicators to monitor what is occurring?