How to solve following error in open loop stepper motor motion system

[nats8]

Hello! I am pretty new at this whole thing and I am trying to troubleshoot a problem. Our setup is as follows: cRIO 9022 with stepper motors, and 9512 modules. Now we run our setup for weeks non-stop and one of our motors needs to be rotating the entire time. We rotate at about 7200 units per second. It usually performs well for 3 or 4 days and after that rotation stops and I get: error -70197 NIMC_startBlockedDueToFollowingError: Start motion is blocked because of following error. Verify the axis feedback and control, and then execute a halt stop before starting the move.

I have done a lot of searching online on how to solve this and I thought I found a solution when I found the "load following error" function. However, I then realized that it falls under he Ni Motion with 73xx controllers. Whereas everything I have been using is NI-SoftMotion. Whenever I tried the function I received this error:   Failed to load shared library FlexMotion32.*:flex_load_follow_err:C. Ensure that the library is present on the RT target. Use MAX to install NI software or FTP to transfer custom libraries to the RT target. I tried using MAX to look at the software installed on RT target, but could not solve the problem.

I am really at a loss here on how to fix the error and keep the motor rotating for 3-6 weeks non-stop. Also I should mention I do not currently have an encoder setup for the motor and I use the "Line-velocity" function under NI-SoftMotion Express VI. to setup the movement. 

Any help would be greatly appreciated! 

[thuyanhl]

Hi,

Did you make sure your axis is set up to have no encoder and to be in a open loop? 

Best Regards,

[nats8]

I believe so, that is that done under the axis configuration page correct?

for feedback I selected none and I made sure that it is set to open loop.  When the movement stops I can't restart it from the program or the interactive panel, it just gets stuck. The way I found to go around that is to go into configuration window and change the feedback to encoder (even though there is nothing there) I get a small error out that says that there is something missing but the rotation starts again. The problem with that is that I can't track the velocity of the motor. 

[thuyanhl]

Hi,

Are you monitoring the position of your motor over time? Does the error occur at the same position every time? It might be possible that the position counter is overflowing after a long amount of time. 

You might want to reset your position after every few hours. 

I hope this helps!

[nats8]

Thank you for you reply and your suggestions. So I had initially thought the same thing and so I added a reset position step. But even with that it still stops. It does not stop at the same position eveytime but the error is always the same. (following error) i saw that when using flexmotion you can de-activate the following error so that this does not happen, is there a way to do that if I'm not using flexmotion?

[thuyanhl]

Hi,

Are you not able to clear the fault and reset the position once you get the error?

[nats8]

So far I haven't, but only because I have not wanted to stop the program that runs it. I tried to fix it by just using the interactive panel and turning off and on the drive or re-starting the movement. So far that did not work at all. But what did work is what I explained above (going to properties and changing the feedback). The reason I did not want to stop the program is because it has a timer that controls other parts of the experiment, so I was trying to fix the one issue without affecting everything else. 

I am assuming you mean to use the clear faults function? I have not tried that. But I assume it would fix it, I just don't know how to use that without disturbing the program. 

[thuyanhl]

Hi,

I believe clearing the fault will not stop your program. You can do that through the interactive panel. 

Could you also tell me what model of drive, stepper motor and versions of LabVIEW and SoftMotion you have?

[nats8]

I know it has been a while. But I am still having issues. The whole setup is a little old and I am trying to update but want to make sure I fix the bugs firts. I have a P7000 Series stepper drive with a motor type: T21NRLC-LNN-NS-00. I am running it in Labview 2011 (I know I need to upgrade) and using softmotion. 

I haven't tried the clearing of the fault. But for a longterm solution I don't want to have an automatic clearfault in the program just in case there is an actual fault? I am not sure if that would end up causing problems. I have tried to find any information on following error and softmotion and/or stepper motors but I cannot find anything to help me. I was looking at this link http://digital.ni.com/public.nsf/allkb/899AE29CB4E3578B8625709D0070A725

but so far I haven't been able to find a solution. ANY help is greatly appreciated!!!!

[thuyanhl]

Hi,

Do you see your Monitor Option in your Axis Configuration to be grayed out? Also, there is a bug related to following errors with open loop control in SoftMotion 2011 with 9512 modules and P7000 drives with no encoder. The reason you are seeing your error might be because the number of steps is limited to an I32 which is 2147483647 steps. This bug was fixed in our SoftMotion 2012 version. 

I hope this helps!