Visa read isn't reading the correct results

[WNM]

I never have used SPM as 99.9% of the steppers around here are run open loop without the benefit of encoders.  Just off hand I'd say you need to get both the motor and the attached encoder working reliably independently and then you tweak the scaling for the encoder readout so that it can track the motor position. Then you just turn it on and it will monitor the following error and stop operation if it exceeds a threshold.  Information on SPM is in both the Galil user manual and Command Reference manual.  You can also find more information if you search for SPM here.

[julianv23]

Thats what im currently doing, I am tracking the position using the encoder and scaling it using the resolution of the drive in order to get it in units of steps.

The issue I am having is when I tell the motor to go to small angles it has been overshooting the position. The issue is that the overshooting is not the same all the time and it only happens to very small angles.

I know how SPM works, my question was how to implement SPM on labview. For example how do I create a subroutine for SPM that my main VI can call in order to check error in motion. I am currently checking motion using a VI I wrote myself.

[WNM]

SPM is a Galil function that you either turn on or turn off and, if it is on, it will set a following error flag within the Galil if the following error exceeds the threshold that the Galil is told to use. LabVIEW does not enter into it except as a means to turn it on or off and to set the threshold and to periodically check to see if the following error bit is set (i.e. ask the Galil what the bit status is).

As for overshoot, that could be a system dynamics problem. And errors for small angles could be a stepper granularity problem (steppers are finite resolution devices and when they stop and power is removed they will always shift to the nearest half step position).