I need a solution for an unidentified glitch in a Labview program.

[GJRodrigo]

I wrote a program meant to control an steppermotor to rotate 90° clockwise and then start rotating at half turn cycles counterclockwise and clockwise, ending with another 90° turn to an upright position when the program is switched off.

The problem is that the motor ends up rotating 270° at random periods of time, sometimes at the beginning of the program, sometimes after 2 hours, etc. Is there any possible way to get over this problem?

Rodrigo Gutierrez 

[Norbert_B]

Rodrigo,

please note that your approach has nothing to do with "close loop control". Additionally, your VI lacks of a proper architecture and the usage of the DAQ Assistant can create delays of unknown size.

I suggest you to look into the standard state machine to clean up the architecture. As second improvement, you should change the DAQ Assistants to DAQmx code and include it into the state machine properly.

I think that this could resolve your issue because i believe that your problem is created due to missing synchronization in regard of execution order.

hope this helps,

Norbert