Different PTO and PWM ?

Hi All,

can im asking about what different PTO and PWM?? can PTO control speed of Motor or by using drive how we want control the speed by PTO or PWM ?

thankyou.

hi,

Pulse-width modulation(PWM), is a modulation technique used to encode a amessage into a pulsing signal. Although this modulation technique can be used to encode information for transmission, its main use is to allow the control of the power supplied to electrical devices, especially to inertial loads such as motors.

Pulse-Train-Output is for precise positioning or precise velocity-control. A pulse rotates the motor by a fractional amount.

It depends on your device, what signal can be used.

hope this helps,

regards,

mopS04

hi,

Pulse-width modulation(PWM), is a modulation technique used to encode a amessage into a pulsing signal. Although this modulation technique can be used to encode information for transmission, its main use is to allow the control of the power supplied to electrical devices, especially to inertial loads such as motors.

Pulse-Train-Output is for precise positioning or precise velocity-control. A pulse rotates the motor by a fractional amount.

It depends on your device, what signal can be used.

hope this helps,

regards,

 regarding your statement, can we do both in same programing? i means for speed by using (PWM) and positioning use (PTO) ???

Hello.

izzqzainal

Hi All,

can im asking about what different PTO and PWM?? can PTO control speed of Motor or by using drive how we want control the speed by PTO or PWM ?

thankyou.

There is much confusion on this topic. People using micro-controllers refer to PWM regardless if it is PTO or PWM. For PLCs it is important to know the difference.

For motion control the PWM and PTO is a substitute for an analog setpoint. Speed and position can be controlled via this digital transmission method. A PLC output is assigned to use PWM or PTO; not both. Only specific outputs are reserved for the function.

:: PWM ::

• Variation of duty cycle while frequency stays constant.
  
  
• T(period) is fixed while it is being used. Normally configured by hardware but can be adjusted by software - not while pulsing.
  
  
• The ratio of T(off) to T(on) can be varied by the software.
  
  
• Motion control: DC motor amplifier cards traditionally use this to provide a setpoint. The change in duty cycle can be filtered to an analog circuit that does not use micro-controller processing.
  
  
• PID loop control can give PWM output out. Alternatively a user program use it as if an analog output which vary the PWM duty cycle. It is speed control only.
  
  

:: PTO ::

• Variation of frequency while duty cycle remains at 50%.
  
  
• T(period) is varied. The control is done from software.
  
  
• The ratio of T(off) to T(on) can be fixed at 50%:50%.
  
  
• Motion control: best known for open loop control of stepper motors. The stepper motor amplifier ensures a fixed distance increment for each pulse received. The duration of the increment is given by the frequency of the pulse. This is more popular to use than PWM, used for stepper motors and servo motors. Position (and speed) is controlled even if only open loop control is used.
  
  
• The PLC provides for motion control. With the S7-1200 FW4.2 a new block is available that can set the frequency. A user program can manipulate directly the frequency. This is helpful for doing speed control of variable speed drives instead of using analog control. Not helpful for steppers/servos.

I hope this was helpful. It can help you if you explain what you need to know for your application as generic questions and answers might not be pushing your application forward.

BR

izzqzainal

 

mopS04

hi,

Pulse-width modulation(PWM), is a modulation technique used to encode a amessage into a pulsing signal. Although this modulation technique can be used to encode information for transmission, its main use is to allow the control of the power supplied to electrical devices, especially to inertial loads such as motors.

Pulse-Train-Output is for precise positioning or precise velocity-control. A pulse rotates the motor by a fractional amount.

It depends on your device, what signal can be used.

hope this helps,

regards,

 regarding your statement, can we do both in same programing? i means for speed by using (PWM) and positioning use (PTO) ???

Please describe your application as the answer will then be very specific.

The answer to your question is yes and not. Yes you can control speed ans positioning of , for example, servo motor>drive and no you can not control the positioning of BLDC motor>driver and it has to do with both the motors and the drives.

Servo and stepper motors are designed to in such a way that they need a specific drives for commutation.  The drives energize specific motor windings in specific succession to control speed and positioning. In the case of of BLDC motors they are speed controlled via a driver that changes the effective voltage supplied to the motor windings and has no more control than that which makes poisoning such motor with a high degree of accuracy very difficult.

Kal

#dP

Hello.

izzqzainal

Hi All,

can im asking about what different PTO and PWM?? can PTO control speed of Motor or by using drive how we want control the speed by PTO or PWM ?

thankyou.

There is much confusion on this topic. People using micro-controllers refer to PWM regardless if it is PTO or PWM. For PLCs it is important to know the difference.

For motion control the PWM and PTO is a substitute for an analog setpoint. Speed and position can be controlled via this digital transmission method. A PLC output is assigned to use PWM or PTO; not both. Only specific outputs are reserved for the function.

:: PWM ::

• Variation of duty cycle while frequency stays constant.
  
  
• T(period) is fixed while it is being used. Normally configured by hardware but can be adjusted by software - not while pulsing.
  
  
• The ratio of T(off) to T(on) can be varied by the software.
  
  
• Motion control: DC motor amplifier cards traditionally use this to provide a setpoint. The change in duty cycle can be filtered to an analog circuit that does not use micro-controller processing.
  
  
• PID loop control can give PWM output out. Alternatively a user program use it as if an analog output which vary the PWM duty cycle. It is speed control only.
  
  

:: PTO ::

• Variation of frequency while duty cycle remains at 50%.
  
  
• T(period) is varied. The control is done from software.
  
  
• The ratio of T(off) to T(on) can be fixed at 50%:50%.
  
  
• Motion control: best known for open loop control of stepper motors. The stepper motor amplifier ensures a fixed distance increment for each pulse received. The duration of the increment is given by the frequency of the pulse. This is more popular to use than PWM, used for stepper motors and servo motors. Position (and speed) is controlled even if only open loop control is used.
  
  
• The PLC provides for motion control. With the S7-1200 FW4.2 a new block is available that can set the frequency. A user program can manipulate directly the frequency. This is helpful for doing speed control of variable speed drives instead of using analog control. Not helpful for steppers/servos.

I hope this was helpful. It can help you if you explain what you need to know for your application as generic questions and answers might not be pushing your application forward.

BR

 thankyou sir for yourfeedback  
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New question published by izzqzainal is split to a separate thread with the subject Cannot increase speed of motor .

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