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Please HELP! Level control program Step 7 v5.5

Created by: bbc91 at: 6/24/2013 9:49 AM (23 Replies)

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6/24/2013 9:49 AM	Rate (0)
bbc91 Posts: 25 Rating: (2)	Hello! i'm a college student in the last year and my final project is to control the water level using a siemens plc i'm a beginer and i wold apreciate very much any help(documentation /model / picture) for the programming of level control ps i managed to establish the connection between my pc an plc
bbc91 Posts: 25 Rating: (2)	Last edited by: bbc91 at: 6/24/2013 9:50 AM
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6/24/2013 10:05 AM	Rate (0)
S7 AUTOMAN Posts: 515 Rating: (56)	Hi, can you please elaborate a bit more, about what exactly is your requirement? what plc are you using? how you are goin to control the level? are you using a level transmitter?
S7 AUTOMAN Posts: 515 Rating: (56)
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6/24/2013 10:45 AM	Rate (1)
bbc91 Posts: 25 Rating: (2)	of course thank you very much i'll attach some pictures as you can see i have 2 on/off switches and 2 potentiometers i was thinking to use the switches as start stop buttons and the potentiometres : one to set the reference and one to simulate the signal receved from a flow transducer Attachment level.zip (269 Downloads)
bbc91 Posts: 25 Rating: (2)	Last edited by: bbc91 at: 6/24/2013 10:45 AM
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6/24/2013 11:01 AM	Rate (1)
Amit_86 Platinum Member Joined: 3/18/2008 Last visit: 8/25/2022 Posts: 1750 Rating: (270)	bbc91 of course thank you very much i'll attach some pictures as you can see i have 2 on/off switches and 2 potentiometers i was thinking to use the switches as start stop buttons and the potentiometres : one to set the reference and one to simulate the signal receved from a flow transducer Hello, As you mentioned in the Subject , Software is Step7 V5.5. Hence you need FB41 PID Block from Standard Library of Step7. You have to Call this Block in Cyclic interrupt OB35. Also have a look a following Threads. PID Controller PID in Step7 Hope this helps...
	VANDE MATARAM.....
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6/24/2013 11:22 AM	Rate (1)
S7 AUTOMAN Posts: 515 Rating: (56)	HI, Find an attached example. Use it as you reference. You can find the FB41 block inside the libraries-standard library-pid control blocks. assign the parameters as mentioned in the example attached. give the desired setpoint in the 'SP_INT', assign the input from your potentiometer to 'PV_PER' (if you are feeding it directly through the AI card or else if you are using the scaled value rather than directly feeding through the AI card, use 'PV_IN' instead. Assign the tuning values as required (P & I value). For more help you can click on the block and F1. First try it in manual mode and c whether you are getting the output and then go for the auto mode Attachment PID BLOCK.pdf (404 Downloads)
S7 AUTOMAN Posts: 515 Rating: (56)
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6/24/2013 11:32 AM	Rate (0)
bbc91 Posts: 25 Rating: (2)	thanks again for your support!!! i'll let you know how things are going..i hope there won't be too many problems left to solve have a nice day
bbc91 Posts: 25 Rating: (2)
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6/25/2013 7:35 AM	Rate (0)
bbc91 Posts: 25 Rating: (2)	hello again! i know you have been very helpfull and i apreciate , i've stayed up all night reading the documentation about pid, pb41 and ob35 as i said before i want to control the level but i have to do this using a flow transducer and an electropneumatic valve, so i'll use a potentiometer to set the reference and depending on the value of that reference the flow's value will rise or drop Can someone please guide me,tell me the necessary steps that i have to make in the creation of the project,i am asking you this because i have very little time at my disposal and te documentations are huge and i can't seem to find a program very simmilar to what i need? thank you very much!
bbc91 Posts: 25 Rating: (2)
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6/25/2013 7:46 AM	Rate (2)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 2/21/2023 Posts: 6794 Rating: (1341)	bbc91 hello again! i know you have been very helpfull and i apreciate , i've stayed up all night reading the documentation about pid, pb41 and ob35 as i said before i want to control the level but i have to do this using a flow transducer and an electropneumatic valve, so i'll use a potentiometer to set the reference and depending on the value of that reference the flow's value will rise or drop Can someone please guide me,tell me the necessary steps that i have to make in the creation of the project,i am asking you this because i have very little time at my disposal and te documentations are huge and i can't seem to find a program very simmilar to what i need? thank you very much! Hello, I guess you want to implement a cascade control structure with FB41.Please read the following topic: Need help in Cascade control method... Best regards Hamid Hosseini
	Demo Channel on Youtube
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This contribution was helpful to 3 thankful Users Ayman Elotaify bbc91 Saeed Bahadori

6/25/2013 7:51 AM	Rate (1)
S7 AUTOMAN Posts: 515 Rating: (56)	hi, create a project in the step7, in the blocks folder add ob35, in ob35 insert fb41 in a network and assign the parameters to it as mentioned in my previous message. first try entering some manual values to the PID block ('MAN') , say 0%,25%,50% and so and see whetehr you are getting the corresponding output at the output side(measure the mA at the corresponding AO channel) and then go for the auto mode. Feed your potentiometer feedback to 'PV_PER' and assign P,I values (for example for P=0.05 and I=4000) and the rest as mentioned in the example. give it a try and get back to us please
S7 AUTOMAN Posts: 515 Rating: (56)
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6/25/2013 8:39 AM	Rate (0)
bbc91 Posts: 25 Rating: (2)	i can't thank you enough for your quick response..... i don't think i can implement acascade control structure, because the only things that i can use to control is oneelectro pneumatic valve and a flow traductor(better said the last time i connected th plc stand only to that valve and to an flow transducer and i was told that it was all i needed to connect).....for wouldn't have i needed at least another valce for a cascade?....i have attached a jpg of the structure Attachment project.jpg (302 Downloads)
bbc91 Posts: 25 Rating: (2)	Last edited by: bbc91 at: 6/25/2013 8:40 AM
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