DC Motor Speed control with Pulse Outputs

Hello all,

I have four DC motors with pulse output and I need to get the 4 motors to run at same speed with the use of a preset number of pulses per second.

I set up a "command table" and a PWM output but it did not work.

The command table gives an error every time I enable it.

I would really appreciate any help or application examples.
 

hi Egatech,

I found this application sample

How do you change the pulse length for the pulse width modulation (PWM) in the user program of the S7-1200 CPU?

hope this helps,

regards,

Egatech

Hello all,

I have four DC motors with pulse output and I need to get the 4 motors to run at same speed with the use of a preset number of pulses per second.

I set up a "command table" and a PWM output but it did not work.

The command table gives an error every time I enable it.

I would really appreciate any help or application examples.
 

PWM  :: pulse width modulation :: variable active phase, fixed frequency
PTO :: pulse train output :: variable frequency, fixed 50% active phase

There is a difference between PWM and PTO for PLCs. The 'command table'  and  'motion control'  goes together with PTO. The PWM control does not have these options.

The selection of PTO or PWM will depend on the power stage used for the motors.

Apologies, I did not explain properly as I was looking at different solutions and got mixed up.

I actually have now 4 linear motors with about 26 or 52 pulses/mm and the speed is controlled via PWM.

The pulses will tell me the speed as some motors are opening or closing, as some motors are a bit faster than others when connected to the same pulse.

I managed to do a speed control as so on, but my PWM is no sending out anything even though that all seems correct.

My apologies for possibly some silly mistakes but this is my first experience with S7-1200 and TIA as unfortunately I took this job assuming the motors would run at same speed and only when they arrived I realised that was not the case.