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FM 350-2 Period Duration Measurement - Time Window

Created by: anelej at: 5/19/2010 3:24 PM (4 Replies)

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5/19/2010 3:24 PM	Rate (0)
anelej Posts: 3 Rating: (0)	Hello, I am working with FM 350-2 and trying to measure a variable period between 10ms and 1s. It is very important that I get the measured values as soon as possible. So, here is my problem: When I take a wide time window, I can't get the measured values quick enough, and with a small time window I can't measure the long periods. Is it possible to change the time window while the programme is running? Is there a way to get measured period when that period is over and not to wait the end of the set time window? Thank You in advance.
anelej Posts: 3 Rating: (0)
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5/20/2010 9:36 AM	Rate (0)
SINAMICS_TO Bronze Member Joined: 4/24/2008 Last visit: 8/2/2024 Posts: 213 Rating: (16)	it is not possible to change the time window in the running program without restart the module. The FM350-2 has a dynamic measuring time. You will get a measuring value back when you get 1 pulse in the time window. For exsample. Signal 2,5Hz time window 100ms You will get the following measurement values (in 100ms windows) -1, 0,0,0, 2500, 0,0,0, 2500,.... So you only need to ignore the 0 measurement values. You can also use the module in counting mode and make your own measuremnt calculation by using the OB35

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5/20/2010 9:51 AM	Rate (0)
anelej Posts: 3 Rating: (0)	Your answer was very helpful. I was wondering about those zeros and how it managed to measure periods grater than time window from time to time. Thanx a lot!
anelej Posts: 3 Rating: (0)
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5/20/2010 10:34 AM	Rate (0)
anelej Posts: 3 Rating: (0)	@Boehser_Onkel, Just one more question. The part with the time window is perfectly clear now, but I am not shure if I understood you well about OB35 and counting mode. Did you mean to count the impulses by FM 350-2 and read the number of pulses periodically in OB35? If I've understood it well, than it is not an option for me because I need a very precise measurement (with an accuracy of 0.005%). Or did I miss something? Danke noch einmal!
anelej Posts: 3 Rating: (0)
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5/20/2010 2:06 PM	Rate (0)
SINAMICS_TO Bronze Member Joined: 4/24/2008 Last visit: 8/2/2024 Posts: 213 Rating: (16)	By using the OB35 you have the problem that you can only calculate a average value. So it would be not useful for you and your accuracy. A better module for you would be the FM350-1 or ET200s1Count. This moduls have a continuous measuring mode. Look in manual of FM350-1 chapter 7.4 picture 7-30. With this module you will not get an output of zero likeFM350-2.

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