2 Axes... 1 home switch? Find Reference

[fluidkinetics]

I am using a NI-7330 Motion I/O card, connected to it is a UMI 7764 motion I/O board. This card is being used for closed loop stepper motors. I am currently trying to write a VI that, for each axis, will rotate each lead screw until the movable objects on the lead screw run into the home switch and once they do the position can be reset to a know value, basically reseting this home switch into a datum/reference position. The goal is to get away with just using 1 home switch, for 2 axes, is this even possible? Is it safe to do this, or would using forward/reverse limits and a home switch work best?

I have run the Find Reference VI with little luck. This simply runs one axis until it hits the home switch, but immediately runs the motor in the opposite direction. From what I've read I'm assuming this is being treated as forward or reverse limit switch, instead of a home switch? Im assuming that something within my MAX settings is incorrect and I was hoping someone with more in depth knowledge would be of assistance.It would be great if I was able to run Axis 1 to the home switch then assign it to some relative postion from the home switch, then do the same for Axis 2.

Thanks

[Highland_Controls · Accepted solution]

Almost any setting in MAX can be overriddin within LabVIEW.  You have an offset move set, so that is why your axis moves after finding the home switch edge.  I would disable the home switch in MAX, then use Smart enable/disable in the find reference settings.  Don't do a an offset move or position reset in MAX.  Use the Find Reference VI, then when that VI completes, you can do an offset move and/or reset position using LabVIEW.

[fluidkinetics]

I figured that out. It was not even getting to the point where the offset move could take place. What was happening was the object was translating to fast and the home switch couldn't read it or something. Once I tried the find reference at a slower speed with the given settings in MAX, it was able to find the reference, sit at the home switch and reset the home switch position to 0. 

One issue I've had since then, would be trying a one axis position move after completing the find reference and setting the home switch as the reference position. So I run the Find reference and at this point the object is at the home switch/position (at position/step = 0). Then I will run the One Axis Move VI to move it to any arbitrary absolute position. But when I first run the One Axis Move VI it only moves about half of a revolution and stops. Then I run it again and it finally moves to the desired position.

What could be causing this hiccup, in my running of the One Axis Move VI?

[fluidkinetics]

Would this have anything to do with the Offset move in place? I didn't realize it till now that when the Find Reference is run, it merely sits at the home switch and doesn't complete the offset move.