Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

Stepper motor with encoder for speed loop mode, using S7-1200

Created by: Rotem at: 11/10/2011 11:15 AM (8 Replies)

Rating (0)

Thanks 0

9 Entries

11/10/2011 11:15 AM	Rate (0)
Rotem Posts: 2 Rating: (0)	I want to control a stepper motor with encoder on it, in speed mode closed loop. I will give a certain speed setpoint and the motor will maintain this speed with feedback from the encoder. Is this possible with S7-1200? What peripheral cards/ modules should I use? If it is not possible with S7-1200 is there any other solution from Siemens?
Rotem Posts: 2 Rating: (0)
Suggestion To thank Quote Answer

11/10/2011 3:03 PM	Rate (0)
Denilson Pegaia Platinum Member Joined: 9/23/2005 Last visit: 3/24/2023 Posts: 4180 Rating: (1332)	hi, witch reference become the step motor drive that you use? PTO? Analogical reference? It has the possibility to connect the encoder directly?
	Denilson Pegaia Siemens Industry Sector Technical Support
Suggestion To thank Quote Answer

11/12/2011 2:09 PM	Rate (0)
Marko Bursic Platinum Member Joined: 9/8/2009 Last visit: 3/15/2023 Posts: 1410 Rating: (146)	You don't need a feedback loop, a stepper motor always mantain the desired speed, if it can't then it stalls and even an encoder feedback wont help.

Suggestion To thank Quote Answer

11/12/2011 4:08 PM	Rate (0)
William_B Posts: 5225 Rating: (1165)	Hi there. Marko Bursic You don't need a feedback loop, a stepper motor always maintain the desired speed, if it can't then it stalls and even an encoder feedback wont help. When the driving speed + ramping is done correctly to suit the mechanical system there should be much of a problem. The problem comes in when there is slip between motor and the actual movement. There measurement of the motion can be of advantage then. I have used an S7-200 and Gecko stepper drive for such applications without feedback.. if you'd like to know. In other application I use a programmable stand-alone stepper drive and motion controller.. but it is not from Siemens so I will not tell you more. My suggestion to (+/-) close the speed loop: A = <Axis name>.MotionStatus.Velocity ....control variable B = [High speed counter set to frequency mode] ....measured variable ERROR = k * A - B where k = [multiplication factor] k = 1 if you have set the actual speed in the setup of the pulse genarator (PTO). Now you have to decide what action you are to take if ERROR becomes too big. Let us say however.. X = [The speed you want to achieve] then ERROR = X - B Then control A so that the ERROR stays small. Now some else should explain how to do that. (Is PI really required?) When the stepper motor is running at a constant speed, there should not be much compensation required. It is however another case when you are doing positioning.. I'll post something in the next post. Rotem: The more info you give the more helpful we can be. Please give us more. Just remeber that high torque, high speeds and short ramp up is servo territory.. a much different game. Greetings. - William
William_B Posts: 5225 Rating: (1165)
Suggestion To thank Quote Answer

11/13/2011 10:00 AM	Rate (0)
Rotem Posts: 2 Rating: (0)	Thanks for all suggestions, problem solved.
Rotem Posts: 2 Rating: (0)
Suggestion To thank Quote Answer

11/13/2011 5:19 PM	Rate (0)
William_B Posts: 5225 Rating: (1165)	Rotem Thanks for all suggestions, problem solved. Rotem, I am glad your problem is resolved. Please explain to me (us) what he problem was and what you did to resolve it. I for one would like to learn from your experience. Thank you.
William_B Posts: 5225 Rating: (1165)
Suggestion To thank Quote Answer

11/14/2011 5:07 PM	Rate (0)
simone.m Posts: 4 Rating: (0)	Hi Rotem, why don't you use a driver with servo mode closed loop capabilities to drive the stepper motor? In this way the drive handles the velocity servo loop and give you following error data as feedback.
simone.m Posts: 4 Rating: (0)
Suggestion To thank Quote Answer

4/4/2012 7:20 PM	Rate (0)
Tranhieu0983 Bronze Member Joined: 9/24/2010 Last visit: 3/3/2023 Posts: 118 Rating: (10)	I had a problem like that. but i feel rotem don't want to say more about this problem. So that, some body can tell more about this problem andexplain. Thank you so much, With me the firstusing PTO. I try but now i can;t finish yet.
	Mechatronic Center Website: www.plcvietnam.com.vn Email : tvhieu.plc@gmail.com
Suggestion To thank Quote Answer

4/5/2012 3:20 PM	Rate (0)
Marko Bursic Platinum Member Joined: 9/8/2009 Last visit: 3/15/2023 Posts: 1410 Rating: (146)	You can see other post, to see the philosophy, until now I haven't had the need to close loop on stepper motor, I rather use more powerfull steppers. ?> (S7-1200) Closing the loop on a PTO

Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Related topics by keywords:

Follow us on