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PID SCALING

Created by: @success at: 6/11/2017 10:22 AM (7 Replies)

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6/11/2017 10:22 AM	Rate (0)
@success Bronze Member Joined: 8/1/2016 Last visit: 9/5/2022 Posts: 152 Rating: (5)	Dear Experts, Please I have been asked to write a program for a boiler steam valve.. The opening of the steam valve has to go along with increase or decrease in temperature of the boiler. Example: if the temperature is at 100 the steam valve should start closing gradually... The opening of the steam valve is from 0...100. Already, I have designed the block for the temperature scaling of the boiler.. But I am stuck with how to use my temperature output to control my valve opening and closing.. I know this should be a kind of PID control system.. Please, I need suggestions and hints on how to go about this.. Thanks for your support...

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6/11/2017 10:42 AM	Rate (1)
zzVss Gold Member Joined: 5/30/2013 Last visit: 3/21/2023 Posts: 112 Rating: (37)	Hi @success, what you problem PiD or scaling? Tray this: Closed-Loop Control of Simulated Controlled Systems in the S7-1500 with PID_Compact V2 connecting the control output of a PID controller to two actuators Example Project for PID Professional Sample program: field simulation for PID Compact Simple PID for flow control 3-Point Stepper Control with SIMATIC S7-1200 (Set 2) 3-Point Stepper Control with SIMATIC S7-1500 Sample program: controlling two actuators Where can you find descriptions and examples of PID control with FB 41, FB 42 and FB 43, and SFB 41, SFB 42 and SFB 43? How can you standardize and destandardize analog values with STEP 7 V5.5 before we use the FB 41, Shall the input and output word be scalled/unscalled first? S314C-2DP analog output scaling PID controller logic implementation Best regards zzVss
	Last edited by: zzVss at: 6/11/2017 10:58:44 AM
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6/11/2017 12:41 PM	Rate (0)
Sachinpatke Silver Member Joined: 12/9/2010 Last visit: 10/8/2022 Posts: 623 Rating: (72)	Hi, U can use FB41 - 'CONT_C'. This PID block is used for single analog output - like in ur case. Coneect ur scaled temperature value to PV_IN ; Analog output to LMN_PER and specify setpoint. You need to tune this PID as per ur process conditions. There are lots of parameters. Use F1 for help.
	If you like the comment, rate it (right top) or thank it (left bottom). One who says he can & one who says he can't, are both correct-Confusius. Automation- C2C, Management Sachin Patke, India.
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6/11/2017 2:19 PM	Rate (0)
@success Bronze Member Joined: 8/1/2016 Last visit: 9/5/2022 Posts: 152 Rating: (5)	Thanks to you all. But is there any formula I can use to create my own PID block.. Like I used in temperature scaling of 4-20ma I didn't use FC 105, I created my own scaling value with this formula... Y= Y2-Y1/X2-X1*PIW-X2+Y1... Please is there any formula like that I can use to design my own Fb 41, if I don't want to use any of the PID blocks in standard library... Thanks to you all in advance..

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6/11/2017 2:46 PM	Rate (0)
zzVss Gold Member Joined: 5/30/2013 Last visit: 3/21/2023 Posts: 112 Rating: (37)	Hi @success, @success . Please is there any formula like that I can use to design my own Fb 41, if I don't want to use any of the PID blocks in standard library... Best regards zzVss

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6/11/2017 3:06 PM	Rate (0)
@success Bronze Member Joined: 8/1/2016 Last visit: 9/5/2022 Posts: 152 Rating: (5)	zzVss Hi @success, @success . Please is there any formula like that I can use to design my own Fb 41, if I don't want to use any of the PID blocks in standard library... Best regards zzVss I need the formula if any please.... And if there is none.... Please let me know...

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6/11/2017 3:51 PM	Rate (1)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 3/23/2023 Posts: 11994 Rating: (2574)	Hello success; If you search a bit on the web you will find many variations on the basic PID algorithm developped by various PLC manufacturers. For example, look at the attachment below. http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/logix-wp008_-en-p.pdf Remember that besides the basic calculations you will have to synchronize the cycle time of your algorithm with the calling interrupt OB it is located in, and also take care of the scaling in and out of the variables, and the output limits of your controller and many other little détails... Good luck in your endeavor, Hope this helps, Daniel Chartier Attachment Rockwell PID algorithm.jpg (139 Downloads)

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This contribution was helpful to 2 thankful Users zzVss metwally mustafa

6/11/2017 5:31 PM	Rate (0)
@success Bronze Member Joined: 8/1/2016 Last visit: 9/5/2022 Posts: 152 Rating: (5)	Dear all, I want to appreciate your responses... Thank you all... The information provided are very helpful..

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