Motion complete VI does not always work

[jmetcalf]

Hello,

[jmetcalf]

Hello,
I am trying to use the Motion Complete VI to wait for a move to a relative position to be complete. Anywhere from 10% to 80% of the time the move complete VI times out. I am using a 7344 Motion Control card connected to a MID-7654 SERVO POWER MOTOR DRIVE.

The sequence that I am doing is as follows:
1. Run at a set velocity until a sensor is true then
2. Halt the motor (with the stop motion VI).
3. Configure the axis to relative position.
4. Load the target position.
5. Start motion on the axis
6. Wait for motion to be complete on the axis
7. Kill motion on all axes.

Any suggestions?

Thanks,
Jon

[TylerS]

Jon,

Just to clarify, when you say you are using the "Motion Complete VI", are you using the Wait for Move Complete.flx? And when it times out, your move is still in progress, but the motor is actually moving? If this is the case, increase the timeout on the Wait for Move Complete.flx. If this is not the case, I need a little more detail about what is actually happening.

[jmetcalf]

TylerS,
Yes I am using the 'Move Complete.flx'. When the MoveComplete VI times out the motor stops. Note, the motor continues to run up to the moment when the MoveComplete times out. I have tried to increase the axis speed in order to complete the move faster, but this does not appear to have any effect.

--Jon

[TylerS]

Does increasing the timeout help?

[jmetcalf]

Tyler,
Increasing the timeout does not help. On related issue (maybe the same problem, I am trying to use the Wait for Move Complete in another program and am having it fail 98+% of the time. The motor only moves a very short distance and is stopped for a long time (several seconds). See the attached bitmap of the segment of the program that isn't working correctly.

--Jon

[jmetcalf]

I increased my deadband from 0 to 10 and that seems to have 'fixed' the problem. Is this the 'best' solution?

[Rodj]

You can either set the deadband to a value greater than 0 (just above your steady state following (position) error), or just turn this feature in move complete criteria off.

Rodger S.