Need help with SCX11 controller programming

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Joined: Wed Oct 26, 2016 5:37 pm

Need help with SCX11 controller programming

Postby dml5452 » Wed Oct 26, 2016 6:09 pm

I purchased two RBK 1.38" steppers motors with the driver package an an SCX 11 controller to control them. I opted for the 400 P/R motors with encoders. I also have a third separate 400 P/R encoder that will measure position of an external shaft. The motors need to be in continuous motion, being 90 degrees out of sync from each other, while the position is constantly changing based on the position of the external shaft.

The motors need to spin at half the speed of the external shaft, so for every 720 degrees of rotation of the shaft, the motors will have completed 360 degrees of rotation. When the external shaft is at 0 degrees, motor 1 should be at 225 degrees and motor 2 should be at 315 degrees. As the external shaft hits 360 degrees in a 720 degree rotation, motor 1 should be at 45 degrees and motor 2 should be at 135 degrees, and so on and so forth.

I've been reading through the operating manual for the SCX 11 and have been trying to determine the best way to accomplish this. I'm assuming a while loop that constantly checks the Encoder position on the external shaft and sets the PC (Position Command) = EC + 225 Degrees would do the trick, but I'm not positive that is how this all works. Further more, give that I have 2 motors and 3 encoders, I'm afraid 1 SCX 11 wont be enough unless there is an easy way to drive two motors with the same output.

If anyone could help me with some insight and possibly a start to the programming, I would be grateful.

Posts: 107
Joined: Tue May 10, 2016 4:48 pm

Re: Need help with SCX11 controller programming

Postby om_tech_support_JS » Thu Nov 03, 2016 10:50 am

Hi dml5452,

The SCX11 controller is a single-axis controller which is meant to be used with only 1 stepper motor driver. The SCX11 will then provide the pulse and direction signals to that driver in order to move the stepper motor.

For your application, you mentioned that the external shaft would be moving. What is moving the external shaft?

As long as the other stepper motors are already in the appropriate starting location, then the only information that needs to be provided to the driver is the new amount of pulses. Say for instance your external shaft moves 720 degrees, then you stated that the other two motors would need the pulse information to rotate 360 degrees. If they start out at the 225 degree and 315 degree locations, then they will end in the same locations.

Therefore, instead of your suggested (Position Command) = EC + 225, I would think you would need to divide the encoder count by 2 and send that as the position. Another way of achieving this would be to adjust the resolution of the two stepper motor drivers. You can adjust the DATA dial on the driver to dial setting 1 to double the amount of pulses needed to travel 1 revolution. This means that you can take the encoder feedback and use it to send to the other stepper motors.

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