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Scan Cycle rate???

Created by: Speedcat at: 3/28/2009 1:15 AM (5 Replies)

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3/28/2009 1:15 AM	Rate (0)
Speedcat Posts: 14 Rating: (0)	How can I Know The Scan Cycle Time Of My Program,Every Time I Upload A Program To The PLC I Access To The Microwin & Open The PLC Menu Then Click On Information He Gives Me Scan Rate Is It The Scan Cycle Time???I Know The Word Is Obvious That It Is The Scan Cycle Time But It's Always In The Range Of 1msec & Amnot Convenient With That Number It's Very Small Specailly Than Filtering The Digital Input Is Enabled(6.4 msec) & The AnalogInput Filter Is Enabled,How Could Be The Digital Filter Is 6.4 msec & The Whole Scan rate Is1 msec!!!!!....Do I Miss Something????????Isnt The Filteration Of The Input Is A Part Of The Scan Cycle Time Or Should I Add The 2 Values????& Howa Can I Know Exactly The Total Scan Cycle Time????Cause My Program Output Depend On Scan Time...
Speedcat Posts: 14 Rating: (0)	Last edited by: Speedcat at: 3/28/2009 1:28 AM Last edited by: Speedcat at: 3/28/2009 1:18 AM
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3/28/2009 11:00 AM	Rate (0)
Darius Platinum Member Joined: 9/28/2005 Last visit: 12/9/2025 Posts: 2957 Rating: (243)	Hello, You see real scan time DI and AI filtering is nothing to do with scan cycle (I could be wrong). As I know filtering of inputs runs separate from program. DI filtering means that you get "1" on input if signal on DI when signal pulse with is bigger than filter setting. AI filtering means runing average of analog signal for given filer time, so its nothing to do with scan cycle of program.
	Best regards, Darius
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3/28/2009 12:23 PM	Rate (0)
Speedcat Posts: 14 Rating: (0)	Thanks darius But I ThinkProgram ExecutionDepend On The Filtered Value So It Has To Wait For It,Am I Wrong..AnywayDo You Think 1msec Is A Correct Time For A Program Of7 Networks???
Speedcat Posts: 14 Rating: (0)	Last edited by: Speedcat at: 3/28/2009 12:26 PM
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3/28/2009 1:49 PM

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dchartier

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Speedcat
Thanks darius But I ThinkProgram ExecutionDepend On The Filtered Value So It Has To Wait For It,Am I Wrong..AnywayDo You Think 1msec Is A Correct Time For A Program Of7 Networks???

Hello Speedcat;
Yes, you are wrong there.
I will let you read the PLC Concepts chapter of the S7-200 Systems manual by yourself so you understand exactly how the analog filter interfaces with the PLC scan.
Also, the most recommended way to read the actual scan time values in the S7-200 is to use the dedicated SMBs:

SM Word	Description (Read Only)
SMW22	Scan time of the last scan cycle in milliseconds
SMW24	Minimum scan time in milliseconds recorded since entering the RUN mode
SMW26	Maximum scan time in milliseconds recorded since entering the RUN mode

Hope this helps,
Daniel Chartier

3/28/2009 3:50 PM	Rate (0)
Darius Platinum Member Joined: 9/28/2005 Last visit: 12/9/2025 Posts: 2957 Rating: (243)	Speedcat Thanks darius But I ThinkProgram ExecutionDepend On The Filtered Value So It Has To Wait For It,Am I Wrong..AnywayDo You Think 1msec Is A Correct Time For A Program Of7 Networks??? Yes you wrong . dchartier suggestion is very useful for you, but basically what it does I wrote you in the first post. So you don't need to wait for an input, but for example if your scan cycle is 1ms and DI filter is 6ms, so you will "see" this input as logical "1" only after 6 program scans. Its other story with analog. You will allways see average of analog value for filter time. If your filter is 6ms for analog so you will see average value for 6ms of analog input. Thats all. You will read your values every scan cycle, but they will change not every cycle.
	Best regards, Darius
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3/28/2009 6:03 PM	Rate (0)
Speedcat Posts: 14 Rating: (0)	Thank You Daniel & DariusYou Realy Helped ,I Got It(Y)(Y)(Y)
Speedcat Posts: 14 Rating: (0)
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Scan Cycle rate???

Created by: Speedcat at: 3/28/2009 1:15 AM (5 Replies)

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Last edited by: Speedcat at: 3/28/2009 1:28 AM

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Scan Cycle rate???

Created by: Speedcat at: 3/28/2009 1:15 AM (5 Replies)

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Last edited by: Speedcat at: 3/28/2009 1:28 AM

Last edited by: Speedcat at: 3/28/2009 1:18 AM

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