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FC41 -Flow PID Control

Created by: Edric at: 5/27/2014 5:03 PM (12 Replies)

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5/27/2014 5:03 PM	Rate (0)
Edric Experienced Member Joined: 7/17/2011 Last visit: 3/20/2024 Posts: 20 Rating: (0)	Hello I have test a program today using FC41 for a flow control(flow meter feed back(4~24mA,0~6.5 m3/h); positioner for the butterfly valve(4~24mA, 0~100 %), the liquid is pumped by a constant speed pump), I switch on the pump and use the function of the FC41, but the LMN is always 0(anyhow I use manual mode or auto mode, in program AUto_Flow_PID=0 or 1 ). Please receive the attached picutures. Anyone who has related experence can give me some hint which parameter I have set is wrong. Thanks in advance! Attachment FC41_1.GIF (423 Downloads)

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5/27/2014 5:08 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	Edric Hello I have test a program today using FC41 for a flow control(flow meter feed back(4~24mA,0~6.5 m3/h); positioner for the butterfly valve(4~24mA, 0~100 %), the liquid is pumped by a constant speed pump), I switch on the pump and use the function of the FC41, but the LMN is always 0(anyhow I use manual mode or auto mode, in program AUto_Flow_PID=0 or 1 ). Please receive the attached picutures. Anyone who has related experence can give me some hint which parameter I have set is wrong. Thanks in advance! Your COM_RST is TRUE.Make it false via VAT.But be careful of jumps in LMN that would be dangerous for your process. PB41 is the Function block accompanying a DB for regulation in STEP 7.
	Last edited by: hdhosseini at: 5/27/2014 8:28 PM Demo Channel on Youtube
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5/27/2014 5:14 PM	Rate (0)
billwest Posts: 510 Rating: (117)	In your graphic, COM_RST is On. This is a complete restart which initializes the block. Turn it off and you should get an output. Good Luck, billwest
billwest Posts: 510 Rating: (117)
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5/27/2014 6:34 PM	Rate (0)
Edric Experienced Member Joined: 7/17/2011 Last visit: 3/20/2024 Posts: 20 Rating: (0)	Dear All, I think my COM_RST is off, as the signal "Circul_Pump6.1_On_DI" is on and I take a negation for it.

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5/27/2014 7:46 PM	Rate (0)
Navnag Platinum Member Joined: 11/21/2007 Last visit: 9/25/2024 Posts: 2325 Rating: (308)	billwest In your graphic, COM_RST is On. This is a complete restart which initializes the block. Turn it off and you should get an output. Good Luck, billwest Hello billwest Edrichas used an Inverted signal at COM_RST so the actual signal sensed by FB41 is '0' , which is perfectly fine. Hello Edric pl check the following : Keep the"EN" ( Enable ) signal - connected to "1" LMN_LLM and LMN_HLM - Output Value Minimum and Maximum values are not visible in your screenshot. Pl check ( default is 0% and 100% ) TI ( Integral Time is set to 50 minutes .. it this what you want ) Pl check if this will solve your problem Hope this helps Cheers Navnag
	There is no such thing as the last bug in a program There are no stubborn bugs, There are only stubborn Debuggers.
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5/27/2014 8:39 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	Navnag billwest In your graphic, COM_RST is On. This is a complete restart which initializes the block. Turn it off and you should get an output. Good Luck, billwest Hello billwest Edrichas used an Inverted signal at COM_RST so the actual signal sensed by FB41 is '0' , which is perfectly fine. Hello Edric pl check the following : Keep the"EN" ( Enable ) signal - connected to "1" LMN_LLM and LMN_HLM - Output Value Minimum and Maximum values are not visible in your screenshot. Pl check ( default is 0% and 100% ) TI ( Integral Time is set to 50 minutes .. it this what you want ) Pl check if this will solve your problem Hope this helps Cheers Navnag I think it is not logical to discuss based on a brief snpashots of an FBD block.To judge with the whole details,I suggest all list of possible signals in a list in a VAT: COM_RST MAN_ON PVPER_ON SP_INT PV_IN MAN LMN_HLM LMN_LLM LMN_P LMN_I PV ER There are some scenarios for always zero in LMN: Saturated Negative LMN_I in case of COM_RST=0 and Manual=0 COM_RST active prior to all other modes Exact value of COM_RST=1 inside the DB,As codes close to end of block are prior in writing to addresses Negative error and negative (LMN_P +LMN_I) in case of LMN_LLM=0 and LMN_HLM=100 PID is simple math with several parameters to be considered all together in a table!
	Last edited by: hdhosseini at: 5/27/2014 9:05 PM // Dear Navnag, I didn''t ask a question.I have no snapshot to share ,I think we should wait for "Edric" for more data. Thanks for information regarding CYCLE ;-) Demo Channel on Youtube
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5/27/2014 9:00 PM	Rate (0)
Navnag Platinum Member Joined: 11/21/2007 Last visit: 9/25/2024 Posts: 2325 Rating: (308)	hdhosseini [I think it is not logical to discuss based on a brief snpashots of an FBD block.To judge with the whole details,I suggest all list of possible signals in a list in a VAT: In fact it is even easier to analyse if you can post a snapshot of your instance DB with Online values. Hello Edric One more question, you have specified the cycle time as 100ms. For this you must call your FC69every 100ms ( e.g. in a 100ms time interrupt OB ) Hope this helps Cheers Navnag
	There is no such thing as the last bug in a program There are no stubborn bugs, There are only stubborn Debuggers.
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5/27/2014 9:05 PM	Rate (0)
billwest Posts: 510 Rating: (117)	I created and FB41 in OB35 and tried to create inputs like your graphic, including the inverted booleans at COM_RST and MAN_ON. GAIN = 1 anf TI = 20 Seconds. I am using an S7-3152PN/DP PLC. and I am running it in PLCSim. The output is changing. If I change the TI to 50 minutes, theoutput still updates. If I turn the MAN_ON boolean to true the OUTPUT goes to the value set in MAN. Are you running the FB41 in an cyclic interruptOB? billwest Attachment D:\Users\WestWD\My Pictures\FB41_OB35.jpg (252 Downloads)
billwest Posts: 510 Rating: (117)	Last edited by: billwest at: 5/27/2014 9:15 PM
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5/27/2014 9:36 PM	Rate (0)
Edric Experienced Member Joined: 7/17/2011 Last visit: 3/20/2024 Posts: 20 Rating: (0)	please receive the attached file for the remaining parameter. And I've call this FB in OB35. Thank you all for your attention! Attachment FC41_2.GIF (340 Downloads)

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5/27/2014 11:01 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365)	Edric please receive the attached file for the remaining parameter. And I've call this FB in OB35. Thank you all for your attention! Hello again, Please, check the attachment.For the best case of fault finding, we want the list of data I listed in form of a VAT.Just change the name of DB from mine "reg" to yours.Without that, our suggestions would be based on guesses.Please, also provide the exact data type for our convenience (Real/TIME/DEC). Also upload part of your project related to PID (or upload the whole S7 program). Have Fun! HD Hosseini Attachment REGULATION.jpg (488 Downloads)
	Last edited by: hdhosseini at: 5/27/2014 11:02 PM Demo Channel on Youtube
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