Why does it always lose count?

[terp]

Hi, all-

I installed PCI7344 to control steppers. I configed it into open-loop stepper control. In the "Find Reference Setting", I selected the "Smart Enable" and "Reset Position"; Set "Offset move", "Primary Position" and "Secondary Position" to zero.

Then I run the labview example program "One-Axis Find Reference with Status Monitor.vi" to find home. Of course once the home position is found, the "Position" in "Current Trajectory Data" is reset to zero. Afterwards I moved the stepper through "1-D Interactive".

Here comes the weird problem. The first time I move the stepper after the Home Position is found, it always lose counts. For example, I put in 10000 in Target Position with the "Relative Position" mode, after the movement is co
mplete, the "Position" in "Current Trajectory Data" shows "9995" (always some counts less than or 10000) instead of 10000. The weird thing is this only happens in the first move, in the moves after that, the positon display will match the step I input.

Any idea why this happen? I tried to disable the Position Reset in the "Find Reference Setting" and use Absolute Position Mode, it seems in either case the problem is gone.....

[Jochen]

I haven't heard about this issue, yet. Which NI-Motion version are you using? The latest version available for download is 6.1.3. You need to install 6.1.2 first and then the maintenance update 6.1.3.

Download links:
NI-Motion 6.1.2
NI-Motion 6.1.3 maintenance update

Please update to the latest version of NI-Motion and also update the firmware on the board in MAX. Please post a new comment to this answer if the problem persists.

Best regards,

Jochen Klier
National Instruments Germany

[terp]

After the update, the problem persists.

For now, my temporary solution will be using Absolute Position Mode for the first move after Home&Reset. But let me know if you dig out something on this issue.