Find Center routine once in a while starts in the wrong direction

[ben64]

I'm using PCI-7332 controller with UMI-7772. Forward and Reverse limit switches are connected to the UMI.

We doing a life cycling test where a 3-phase stepper motor perform 300000 cycles (120 pk-pk at 216 pps). Every 100 cycles the system is recentered between the limit switches, the initial search direction is set to "forward" but once in a while it starts it search in the opposite direction generating error -70119 (The desired move cannot be completed because the limit input is active in the direction of travel) when the reverse limit switch is hit. The 1D Find Center.vi is used to perform the center operation.

Any idea of a possible cause?

Ben64