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Can anyone tell me how to choose PID_3Step in v10.5?

Created by: majki1980 at: 6/17/2011 4:25 PM (5 Replies)

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6/17/2011 4:25 PM	Rate (0)
majki1980 Posts: 21 Rating: (1)	Can anyone tell me how to choose PID_3Step in v10.5? Is it possible? Now I can only check PID_Compact. Thank you! Splitted from S7-1200 PID limiting output.
majki1980 Posts: 21 Rating: (1)	Last edited by: O_Moderator at: 6/17/2011 4:28 PM new subject after splitting
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6/20/2011 1:01 PM	Rate (0)
Denilson Pegaia Platinum Expert Joined: 9/23/2005 Last visit: 11/4/2024 Posts: 4351 Rating: (1452)	Hi, the PID_3Stepis just released in V11.
	Denilson Pegaia Siemens Industry Sector Technical Support
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This contribution was helpful to 1 thankful Users Tomy Master

6/21/2011 12:51 PM	Rate (0)
majki1980 Posts: 21 Rating: (1)	Thanks! I thought that it is possible to use it in v10.5.
majki1980 Posts: 21 Rating: (1)
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6/22/2011 6:26 PM	Rate (0)
Denilson Pegaia Platinum Expert Joined: 9/23/2005 Last visit: 11/4/2024 Posts: 4351 Rating: (1452)	Hi, it is not near to be ideal, but you can use a analogical PID, with comparators to perform a 3 STEP PID...
	Denilson Pegaia Siemens Industry Sector Technical Support
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6/23/2011 11:21 AM	Rate (0)
koenb Silver Member Joined: 6/26/2009 Last visit: 11/6/2024 Posts: 122 Rating: (23)	Pegaia Hi, it is not near to be ideal, but you can use a analogical PID, with comparators to perform a 3 STEP PID... Looks like the goal is to control a modulating control valve. If this valve or positioner can give a analog feedback signal with his actual position than it is easy to output the signal open or close and it can work stable if hysteresis for the compare is in balance with the mechanical characteristics . If there is no feedback signal then I make a simulation what the position should be based on the time that signal is send to change the position . Therefore I use a cyclic interrupt . If the valve is opening , add a fixed value the simulated position. If it is closing then subtract that value. The fixed value is related to the opening / closing time of that valve and the time for the interrupt. then in the same block compare PID output with simulated position to control the digital outputs that powers the valve or positioner. If the ouput to open or close is on for a time longer than the valve's action time then you can re-init the simulated position. I have this running in some projects and it works stable. Hope that this can help.

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10/13/2011 5:38 AM	Rate (0)
BOC1_NZ Posts: 2 Rating: (0)	Hi, Is it possible to use the PID_3Step with a firmware version 1.0 CPU? If not what would you recommend for PID control of a modulating valve. Thanks, Brian
BOC1_NZ Posts: 2 Rating: (0)
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