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Totalzer problem inOB35

Created by: daad at: 5/21/2012 6:41 PM (14 Replies)

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5/21/2012 6:41 PM	Rate (0)
daad Silver Member Joined: 10/31/2011 Last visit: 11/12/2024 Posts: 400 Rating: (5)	Hello Everyone, I m using FB100 totalizer called in ob35 to measure steam in ton and input is stem flow per hour,But it shows value less then actual.The input parameters are cycle time 100ms interval 1H. can anyone help me...

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5/21/2012 8:03 PM	Rate (0)
Ayman Elotaify Platinum Expert Joined: 5/28/2008 Last visit: 11/6/2024 Posts: 4516 Rating: (839)	m.shoaib khatana Hello Everyone, I m using FB100 totalizer called in ob35 to measure steam in ton and input is stem flow per hour,But it shows value less then actual.The input parameters are cycle time 100ms interval 1H. can anyone help me... Hello, Are you sure of the calibration of AI signal that represents the flow signals which should be an input of the totalizer function? Are you using the following function? If not. Please try it and feedback us with results. How can you accumulate physical flow measurements (e.g. mass flow rate, flow velocity) to an overall value? Hope this helps.
	Ayman Elotaify
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5/21/2012 8:36 PM	Rate (0)
daad Silver Member Joined: 10/31/2011 Last visit: 11/12/2024 Posts: 400 Rating: (5)	Dear Ayman, I m using the same block and AI value is working correctly..

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5/21/2012 8:55 PM	Rate (0)
Amit_86 Platinum Member Joined: 3/18/2008 Last visit: 12/8/2023 Posts: 1750 Rating: (272)	m.shoaib khatana Dear Ayman, I m using the same block and AI value is working correctly.. Hello Sohib, is it possible to share your block codes here? if yes, we can help you better.
	VANDE MATARAM.....
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5/21/2012 9:26 PM	Rate (3)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 11/18/2024 Posts: 3027 Rating: (1057)	Hello m.shoaib khatana You are doing 36000 additions to calculate the Total (one addition every 100ms over one hour). What this means in your case is that your AI value (which is an hourly flow value) gets divided by 36000 and the fraction of that actual value is then addedto the total every 100ms. The precision of a floating point value is "only" 6 decimal placesand as you add a rather small value to an every increasing larger total, the required alignment of the exponents will lead to a loss of precision (values get truncated in this alignment). This will in your caseleadto an accumulated value that is too small and you'll find more info on this at How accurately can I calculate with REAL numbers that are used in extensive formulas? Possible Solutions: 1.) Do a totalevery minute and add these totals together 60 times to get the hourly total. 2.) If your steam flow is rather steady, call the totalizer block only lets say every 10 seconds instead of every 100ms. Give it a try and please let us know if it helped.
	Last edited by: fritz at: 5/21/2012 9:46 PM Changed the term"digit" to "decimal places" to remove ambiguity (thanks Juergen) 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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5/21/2012 9:28 PM	Rate (0)
daad Silver Member Joined: 10/31/2011 Last visit: 11/12/2024 Posts: 400 Rating: (5)	Here code in ob35 CALL "Totalizer" , DB200 IN0 :=DB1.DBD48 IN1 :=T#1H IN2 :=T#100MS IN3 :=M700.0 OUT4:=DB8.DBD8

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5/21/2012 11:25 PM	Rate (0)
Ayman Elotaify Platinum Expert Joined: 5/28/2008 Last visit: 11/6/2024 Posts: 4516 Rating: (839)	m.shoaib khatana Dear Ayman, I m using the same block and AI value is working correctly.. Hello, To what extent there are a difference between actual totaizier and output of totalizer function? And please check that the Cycle Input of the function is equal to OB35 time. And also please check that output of this function is not accessible in whole software except OB35. Hope this helps.
	Ayman Elotaify
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5/21/2012 11:59 PM	Rate (0)
Selvam_viji Experienced Member Joined: 11/7/2011 Last visit: 11/17/2023 Posts: 14 Rating: (0)	Hello Mr.Shoaib, For cyclic-time instead of using 100 ms use 10 ms.it will give u exact totalizing of the flow.
	Last edited by: Selvam_viji at: 5/22/2012 12:02 AM
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5/22/2012 6:04 PM	Rate (1)
fritz Diamond Expert Joined: 10/7/2005 Last visit: 11/18/2024 Posts: 3027 Rating: (1057)	Selvam_viji For cyclic-time instead of using 100 ms use 10 ms.it will give u exact totalizing of the flow. Hello Selvam_viji assuming my theory that the problem is caused by the precision of a floating point value is correct, I'm afraid to say that your suggestion will make the problem worse instead of better.
	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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This contribution was helpful to 2 thankful Users IBN-Service Ayman Elotaify

5/22/2012 6:47 PM	Rate (0)
daad Silver Member Joined: 10/31/2011 Last visit: 11/12/2024 Posts: 400 Rating: (5)	Hello, The totalizer shows less value than original. If it is problem of truncation then value can be roud off but not decrease as much.

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