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STEP 7 Additional Software

PID implementation

Thread Starter: BulentO   Started: 12/23/2006 12:01 PM   Replies: 1

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  12/23/2006, 12:01 PM
BulentO
Joined 7/23/2006
Last visit: 10/5/2011
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Dear Sir,
May be this question was asked before but i searched this Forum but could not find any satisfying answer.
I want to control a water valve according to a tank temperature in my automation task. details are ;  Tank temperature Set Point (SP) : 25 degree , allowed band width is +, - 2 degree (27-23) .my high limit is 35 degree and minimum tank temp is. 10 degree .
I want my water valve fully open %100 at 35 degree and fully closed at 10 degree.
I studied this problem but coulndt solve. in FB41 manipulated value LMN goes suddenly to 100 when temperature goes over 27. and goes suddenly to 0 when temp. below 23.
for example I want my valve to open % 70-80 when goes over 27.
How can i configure these parameters in FB41. also information i used are Gain :1 , PV_FAC :1 , LM_HLM : 100, LM_LLM : 0,   TI time :20 sec, TD time 20 sec. no manuel control selected.
İ called also this block in OB1.
Please inform me as soon as possible because now the task is controlled manually.

Best Regards,
Bulent Ozigci
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  12/23/2006, 12:44 PM
Late
Joined 1/7/2006
Last visit: 4/30/2013
Posts: 2667
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Hi B,

FB41 is a PID block and can not use certain stands for the output, you then have to built them by your self on the outside. blush
 
The blocking of the valve for certain places (min/max) is easily to do with the minimum and maximum range of the output of FB41.

With Modulaire PID you can do this very easy. Thats a package to built all kind off controllers that are not standard. astonished

See the handbook: Modular PID Control and Modular PID Control Getting Started for more infornation and possibilitys of the modular PID blocks. cool

So you might use this blocks or you have to built it around FB41 (Tip: block the controller when you are on a range where you didn't want that the valve is opened further or less, because you will be get a windup of the I-action of the PID controller). cool
I hope that the answer will help, if you have still questions, don't hesitate to ask me.

All the best, Late
Never say never, think in solutions, not in trouble......
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