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Setting coils come on as soon as PLC is started

Created by: Gerstudent at: 3/13/2009 2:04 AM (7 Replies)

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3/13/2009 2:04 AM	Rate (0)
Gerstudent Posts: 5 Rating: (0)	Hello, Im using a CPU315-2DP PLC and Step 7 on PC to program it, The problem is that set coil are turning on as soon as i turn on the PLC, even if the ladder logic diagram doesnt let them as a result my program isn't working and its getting quite frustrating as i'm under a serious time limit to get the PLC runnig. If i could any help or even information on set coils id be very grateful! Thanks Ger
Gerstudent Posts: 5 Rating: (0)
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3/13/2009 8:14 AM	Rate (0)
Aret Posts: 2348 Rating: (259)	Guess you should place your code/diagramm here :^)
Aret Posts: 2348 Rating: (259)
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3/13/2009 9:03 AM	Rate (0)
UMENCHO Diamond Member Joined: 3/21/2006 Last visit: 4/12/2023 Posts: 10221 Rating: (1176)	Hello Aret is right. You would be receive faster decision for the problem. Anyway, I'll try one shot in the dark. Did the CPU's lamp "FRCE" is light on? regards

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3/14/2009 11:55 AM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 3/8/2023 Posts: 703 Rating: (96)	Hello, another guess The variablewhich the SR is applied on is located in the DB sothe valueremains even through the restart of the PLC. If you want the variable to be cleared while restart you should use memory bit or initiate the variable in OB100. Regards Sydney

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3/16/2009 5:44 AM	Rate (0)
Gerstudent Posts: 5 Rating: (0)	Sorry about that, totaly forgot to add the attachment, any help? its M5.5 that keeps getting set on Attachment untitled1.JPG (55 Downloads)
Gerstudent Posts: 5 Rating: (0)	Last edited by: Gerstudent at: 3/16/2009 5:46 AM
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3/16/2009 2:08 PM	Rate (0)
Sydney Gold Member Joined: 1/4/2008 Last visit: 3/8/2023 Posts: 703 Rating: (96)	Hello, have you checked the cross-references about use of M5.5 (could be also used as byte, word or dword) and T4? Also check the preset value for the timer or you can put there s5t#1m for testing to be sure that it doesn't affect the logic. Regards Sydney

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3/17/2009 3:32 PM	Rate (0)
Aret Posts: 2348 Rating: (259)	On turning on M area is reseted to zeroes, so M1.2, M5.5 and M7.3 =0. So on turning T4 must not run. T4 would run as soon M1.2=1, M7.3=1. If T4 runs immediately then something sets these bits. Another thing - you take Db1.DBW4 (S5time i supose?), then convert it to INT. First mistake is to supose, that you get seconds(or 10/100/10000 ms) here. Don't forget, that timebase is also converted as highest digit! Next, you substact 1200.You can't do it, because 1 means timebase 100ms, so 200*0,1s=20s. If you want to substarct 20 seconds you should check DB1.DBW4 timebase. If it's 10ms - it's impossible, with 100ms you should substact 200 (by the way, are you sure you won't get negative number?), with 1s you should substract 20, with 10s timebase - only 2. Next - result of substraction is stored in DB1.DBW8 and you use it for timer. But it's INT datatype, not S5Time or BCD, so 1 more conversion needed atleast.
Aret Posts: 2348 Rating: (259)
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3/23/2009 1:49 PM	Rate (0)
NSLaur Posts: 22 Rating: (2)	Hi Try 2 thing: 1: Have you made some area remanent. Some like this: Mx.x .. M y.y and is writing if Mx.x = 1 the set coil 2: To control if it is your program. Try in first line of OB1 = write instruks BEA -> Program controlBlock End Unconditional then no code is executed
NSLaur Posts: 22 Rating: (2)
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