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SFB problem for S7400H - CPU 414H-3DP

Created by: Wave at: 8/2/2010 10:08 AM (9 Replies)

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8/2/2010 10:08 AM	Rate (0)
Wave Experienced Member Joined: 4/23/2007 Last visit: 1/12/2023 Posts: 58 Rating: (3)	Dear Experts, A colleague of mine is currently on site. He is facing a problem with SFB5 (TOF). The timer doesnt seem to work as expected. The output value of timer shows junk value and the boolean output Q always stays 1. He has recreated the DB, downloaded the DB but still the problem exists. Also, we move value 0 to .STATE variable of the instance DB of the timer to reset it. Is it the one creating this absurd problem? Regards, Wave
	"There is no spoon."
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8/2/2010 10:21 AM	Rate (0)
IBN-Service Posts: 8946 Rating: (995)	May be, the instance - DB is used twice?
IBN-Service Posts: 8946 Rating: (995)
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8/2/2010 10:39 AM	Rate (0)
Wave Experienced Member Joined: 4/23/2007 Last visit: 1/12/2023 Posts: 58 Rating: (3)	Nope. Double checked that first :) Regards, Wave
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8/2/2010 11:08 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 6/1/2023 Posts: 2966 Rating: (1025)	Wave Also, we move value 0 to .STATE variable of the instance DB of the timer to reset it. Is it the one creating this absurd problem? Hello Wave this is a bit weird, a "0" PT Time setpoint value should disable the IEC Timer completely, which means the Output will never be On(unlike S5 Timers where a "0" Time setpoint means just that - a delay of 0 seconds). I'd say something else is going on in that FB, can you perhaps post you logic here for evaluation?
	Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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8/2/2010 11:14 AM	Rate (0)
Wave Experienced Member Joined: 4/23/2007 Last visit: 1/12/2023 Posts: 58 Rating: (3)	Is there a limit for the number of SFBs that I can use in my program? Regards, Wave
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8/2/2010 11:16 AM	Rate (0)
Wave Experienced Member Joined: 4/23/2007 Last visit: 1/12/2023 Posts: 58 Rating: (3)	I move 0 to the <TIMER_INSTANCEDB>.STATE variable. Not the time value. This disabled the timer. Regards, Wave
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8/2/2010 11:31 AM	Rate (0)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 6/1/2023 Posts: 2966 Rating: (1025)	Wave I move 0 to the <TIMER_INSTANCEDB>.STATE variable. Not the time value. Isee (and obviously did not read your original post properly). Well, in that case I'd say that it can explain the "odd" behaviour (I haven't tried or tested this). The "STATE" variable is an SFB internal STAT variable, sincethe SFB is know How protected and the meaning of the "STATE" variablenot explained in theSFB's Help, you are "gambling" a bit by writing to it. Having said that, if your intent is to actually disable the Timer,why not write 0 to the PT Time Setpointinstead (it works rather well with IEC Timers)? I hope this helps P.S: You are only limited by available memory and/or DB's when it comes to usage ofIEC SFB timers.
	Last edited by: fritz at: 8/2/2010 11:32 AM Added P.S: Cheers fritz The advice and opinion given in this thread is that of the author and does not necessarily reflect the views of I S Systems Pty Limited. To find out how I S Systems can help you with your automation needs please visit www.issystems.com.au.
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8/2/2010 11:34 AM	Rate (0)
Wave Experienced Member Joined: 4/23/2007 Last visit: 1/12/2023 Posts: 58 Rating: (3)	Thanks fritz. I did as you said. Changed the time value to 0ms. This resets the timer. But the problem is when I give it the time value, it doesnt work as it is supposed to. I removed one of my timers and then checked this. This time it works. Which makes me think. Is there a limit on the number of SFBs that we can use in the program? Regards, Wave
	"There is no spoon."
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8/2/2010 11:36 AM	Rate (0)
IBN-Service Posts: 8946 Rating: (995)	Wave Is there a limit for the number of SFBs that I can use in my program? Regards, Wave Just the size of memory / max. no. of DB.
IBN-Service Posts: 8946 Rating: (995)
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8/2/2010 11:47 AM	Rate (0)
Wave Experienced Member Joined: 4/23/2007 Last visit: 1/12/2023 Posts: 58 Rating: (3)	A screenshot of the logic that he has sent me. This is only a test logic. If this works we need to implement it in the entire program. Regards, Wave Attachment PROBLEM.JPG (44 Downloads)
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