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Newbie Help for Stepper Control (V350-35-TRA22)

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Hello All,


I apologize for the VERY basic questions I am about to ask but I am new to using a PLC to control a stepper motor.


I have the drive and motor. I read the information included in Visilogic. I am still confused.


I hate to ask but can someone please provide me with basic program to control the stepper drive. I want to provide an RPM and FWD/REV bit. I will answer any questions and will be monitoring this thread constantly over the next few days.


Thank you in advance. Again, I apologize for such basic information but once I have a decent example I should be able to pick it apart and understand things.

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There are two ways you could set this up: either through PTO programming, or set the high-speed output for Step Control in the hardware configuration.


We can set the HSO in the hardware configuration then give a frequency and duty cycle for the output to run at.  Once you enable the "Run MB" the output will give a high speed pulse.  It will also report back a "Current Position" and you may mtach this to a "Target Position" (where you's like to be).  Once this is set up, you can then program a normal digital output to conotrole the direction.


PTO is a little more advanced, but will allow you to arrive at the same outcome.  We do have an example of this in the VisiLogic software (Help Tab: Examples/Version 900/ Project Examples/ PTO/ V350_PTO plus jogging example.vlp.  Please note, we also have a tutorial on how to set this up as well: http://www.unitronics.com/support/webinars/pto


Please let me know if this helps or if there's anything I can explain further.

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If I leave the target '0', will it run indefinite? If not, how would I accomplish this?

Is using an accel and decel typical in stepper motor applications?


Leaving the target at '0' will disable the output from running.  The target position is used to stop the output from continuing once it has reached its destination.


To run the output indefinitely, just set the output up as a "PWM Ouput" in the HW configuration.  This will not provide a current and target position, and will let you run the output as long as you wish.


Acceleration and Deceleration are usually used to protect the motor from the high inrush current (starting the motor abruptly).  however, your driver may already be set up to protect the motor.  It really all depends on the system, the components, and whether you believe it is important or not.  If this is not a long lasting project, and maybe only for demo/prototyping use, it might not be important to program acceleration and deceleration for the motor.  However, if you wish to have this project around for years and want to protect the longevity of teh motor, programming this in may be essential.  In that case, I would highly suggest programming with PTO.


Hope this helps.

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First off, I truly appreciate all the help. In my application I need to run a motor indefinitely (one mode)  and as described in PTO, run for a certain number of pulses (another mode). Would I be best with just using PWM to drive the stepper and use a timer when I need a certain number of pulses?

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Either way works, it just depends how precise you need to be and how much programming you want to do.


PWM programming will be much simpler and quicker to set up.  However, running teh output with a timer will not result in a precise stopping point.  For instance, you may wish to go only 500 pulses, but end up going 512 pulses or something like this.


PTO programming will be a little more extensive to set up, but it more accurate when driving a stepper motor.  In order to "indefinitely" run the motor, you can "jog" the motor for however long you wish.  Please see the end of the example program, V350_PTO plus jogging example.vlp, for a better understand on how to program the "jogging" feature.


Hope this helps.

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