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How to control 3 flow control valves with positioners

Created by: Thura at: 3/27/2012 3:52 AM (16 Replies)

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3/27/2012 3:52 AM	Rate (0)
Thura Posts: 4 Rating: (0)	Dear All, I am a begineer in PLC. My project is using CPU412-3H redundancy system. All I/O modules are conected to 2 ET200M. In my project, i have 3 flow control valves(solenoid valves) (2 are on duty and one is on standby). For each control valve, i want to open 30% on startup. After some time delay, the valve should be gradually open up to 100%. When the valve is to be closed, it should also be gradually closed. Flow meter output is 4-20mA and positioner for the valve is using 4-20mA output. Can i use OB35 and FB58? If so, how can i do it? Thanks, Thura
Thura Posts: 4 Rating: (0)
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3/27/2012 7:13 AM	Rate (0)
TIBI68 Gold Member Joined: 12/1/2009 Last visit: 10/27/2024 Posts: 672 Rating: (147)	Hi Thura, there are soo many ways to "kill the cat". Can you give us some more information about the setup. Maybe a small sketch with the layout of the valves and the flow transmitter. Does allthe valves havethe same dimension? If you have a function description as well that would be even helpful to us. Regards.
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3/27/2012 11:06 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 10/26/2024 Posts: 6852 Rating: (1365)	Thura Dear All, I am a begineer in PLC. My project is using CPU412-3H redundancy system. All I/O modules are conected to 2 ET200M. In my project, i have 3 flow control valves(solenoid valves) (2 are on duty and one is on standby). For each control valve, i want to open 30% on startup. After some time delay, the valve should be gradually open up to 100%. When the valve is to be closed, it should also be gradually closed. Flow meter output is 4-20mA and positioner for the valve is using 4-20mA output. Can i use OB35 and FB58? If so, how can i do it? Thanks, Thura Hello , For me "solenoid valves" are binary actuators and used for safety reasons besides "positioners". If you are using positioners solely , you have option of using PID algorithm and in case of flow, FB41 is recommended. See the samples here: PID Control Package - FB41 Samples FB58 is optimized for temperature loops. Best regards, Hamid Hosseini
	Demo Channel on Youtube
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3/27/2012 3:11 PM	Rate (0)
RugbyGuy Silver Member Joined: 1/15/2009 Last visit: 4/19/2024 Posts: 316 Rating: (40)	Hi Thura, I guess the first question I will ask is how are you programming? Is this with PCS7? With S7 controllers and ET200 IO sounds like you might be. If its PCS7 I can help you. If it is not.. then I would not be best for advice
	The best location for all PCS 7 content (manuals, guides, application notes, FAQs, and videos). https://support.industry.siemens.com/cs/ww/en/view/63481413
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3/28/2012 4:05 AM	Rate (0)
Thura Posts: 4 Rating: (0)	Dear TIBI68,hdhosseini,RugbyGuy, Thank you all for your interest and help. I am using Step7 V5.5 SP2 for programming. Please refer to attached picture for the process. Thanks and best regards, Thura Attachment Layout.JPG (737 Downloads)
Thura Posts: 4 Rating: (0)
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3/28/2012 8:46 AM	Rate (0)
TIBI68 Gold Member Joined: 12/1/2009 Last visit: 10/27/2024 Posts: 672 Rating: (147)	Hi Thura, with a quick look at you layout, thanks by the way, I would say that the standard PID should do the job. Hosseini gave you already some information about it. So first play with it "PLCSIM" and get your PID to work to hold the setpoint. Meaning when flow gets to high, the output of the PID should close the valve and opposite. The initial ramping up and later down needs to be programmed seperatly. For that you will have to override and bypassthe PID output to the FCV. Ramping up/down is simple increasing/decreaing a value. Either by timer or Interrupt OB. If you require further help let us know. Regards.
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3/28/2012 11:48 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 10/26/2024 Posts: 6852 Rating: (1365)	Thura Dear TIBI68,hdhosseini,RugbyGuy, Thank you all for your interest and help. I am using Step7 V5.5 SP2 for programming. Please refer to attached picture for the process. Thanks and best regards, Thura Hello , This is simply possible to implement by FB41. Put the control loop in manual mode on 30% for 30 minutes.It can be done by utilizing a loop enable and a timer output to change from manual to automatic mode. Please note, changeover from manual to automatic is not always bumpless.For more information about this refer here:Bumpless PID For more control function options refer here: http://support.automation.siemens.com/WW/view/en/1137082 Best regards, Hamid Hosseini
	Demo Channel on Youtube
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3/29/2012 12:14 PM	Rate (0)
Thura Posts: 4 Rating: (0)	Dear TIBI68, Thank you for your information. But my problem is that i do not know exactly how to implement it in actual programming. Can you please give me more details about how to program the control in Step7? Thanks and best regards, Thura
Thura Posts: 4 Rating: (0)
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3/29/2012 12:16 PM	Rate (0)
Thura Posts: 4 Rating: (0)	Dear hdhosseini, I will read it through first. Thank you. Thanks and best regards, Thura
Thura Posts: 4 Rating: (0)
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3/30/2012 12:01 PM	Rate (0)
TIBI68 Gold Member Joined: 12/1/2009 Last visit: 10/27/2024 Posts: 672 Rating: (147)	Yes Thura, I also give you the advise to read yourself first through the suggested documentation. Play around with the examples and see what happens by changing the input parameters of the PID. That will help you to understand the function of the PID controller better. After you will be able to implement it into your application the right way. Come back if you need still further support. Regards.
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