why only Axis 1 is permanently active?

[Rodj]

Microstepping is a function of the stepper drive. I looked your drive up on the web. It can only be set to whole or half step mode.

Lets see if we can do a test. Does the motor stop long enough for you to go over to it and try and turn it [by hand]? If so, please do try and turn the motor. If it is "slipping" it will have a very distinct feel to it. It doesn't turn freely and it doesn't hold. Sort of a sloppy feeling. If you can do this, we can make sure we are going down the right path.

Thanks,

Rodger S.

[Gram]

Thanks again, Rodger, particularly for helping me identify whether the drive can be set to microstepping. Yes, I can turn the shaft driven by the motor when it stops, although the stop period is fairly short. I can turn it by hand, absolutely not freely, but I cannot describe whether it holds or not. When I turn this shaft, I can sense that it could possibly to help resuming of motion??? (I am not so sure about it). However, I let the motor run back and forth for same steps, and measure the travelling distances associated with them, I can find certain error for each time (different travelling distance) regardess of same steps I set.

[Rodj]

I'm positive you are seeing the results of the stepper motor slipping.

This can happen because of over acceleration/deceleration, over velocity, or you may need to set a base velocity value.

The first two, you can play around and see if they have an effect.

Base velocity affects the trajectory generation and stepper output. Basically it forces the system to start and end a move at a velocity > 0. This is because steppers in whole step and sometimes half step mode require a minimum frequency to even start moving.

See the help for Load Base Velocity.

Rodger S.

[Gram]

Thanks, Rodger,

I am playing around the parameters as you suggested. They do have effects on motion. However, if I set higher velocity, the motor will not stop (higher torque?). I have to use low velocity in my application, as this application in fact is associated with a scaled model in a geotechnical centrifuge. Stop occurs in low velocity cases, even though I change the acceleration/deceleration, and base velocity. Say, I set velocity to be 5 rpm, what would be the appropriate values for acceleration/deceleration, and base velocity.

[Rodj]

Unfortunately this is not an exact science where I can plug in your numbers and give back an answer. It is something that you will need to play with your system and determine what its capabilities are.

I would actually recommend you get a drive that can do micro stepping. This will give you much better control/smoothness at low velocities.

Rodger S.

[Gram]

Many thanks, Rodger, I will continue to play around the parameters. And discuss with my colleagues and see if we can get a microstepping drive.

[Gram]

Further to my questions. I take out the motor from the rest of mechanical components, and hold the motor by hand. I can still feel the interrupted impulses with slight oscillation. I am not sure whether the motor can output continuous and smooth pulse? I want to monitor the pulses generated from the 7334/UMI7764 card by an oscilloscope, and can you advise me how to make such connection? Thanks in advance.

[Jochen]

Connect your probe between the step output terminal and a GND terminal of the UMI.

Jochen

[Gram]

thanks, Jochen, I also want to know what is supposed to be the normal output from the scope?