Motor Stalls Below Max RPM

[1eyedjack]

I'm working with two stepper motors from NI and I'm having trouble getting it up to speed.

Here is my setup:

2 Stepper Motors (CTP12ELF10MAA00)

2 Encoders

MID-7604 Drive Box

PCI-7330 motion controller

The motors are supposedly rated to 3000 RPM but I can't get them past 720 RPM without stalling; even runnning them in the Measurement and Automation explorer 1-D interactive.

Is there something wrong with the motors, or is there special care that needs to be taken at higher RPMs?

Thanks,

Arthur J.

[Highland_Controls]

Are the motors driving anything?

[Greg-H]

Hi,

In addition to the above question, what are your acceleration deceleration values set to?

Regards,

Greg H.

[1eyedjack]

Thanks for the questions.

I removed all loads, so that they were just running bare. I set the accel and deaccel values to 100. But they still stall at about 700 RPM.

[Highland_Controls]

Make sure your scaling is correct.  Set them to move at 60RPM, and see if you are getting about 1 rev/sec.  I just want to make sure you are not off by a factor of 4.

[Buechsenschuetz]

You'd better try to run the motors WITH their operational load attached. Stepper motors tend to resonant vibrations when there is no mechanical load attached. This may lead to stalling at certain rpm (or steps/sec) values. 

Also, are you using the motors in full-step mode? Most motor drivers allow for microstepping, i.e. dividing each full step (as given in the motor data) into "substeps". All step-number related values entered in MAX (or any other driver software) have to be multiplied by the microstepping factor. You should use at least 4 microsteps per step. The motor will run much smoother and sometimes stalling at certain rpm values can be avoided.  

[AnalogKid2DigitalMan]

Another thing to check is to make sure the DIP switches on the 7604 are set properly for your motor parameters.

-AK2DM