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Integration Time

Created by: tulinho at: 6/29/2011 7:44 PM (8 Replies)

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6/29/2011 7:44 PM	Rate (0)
tulinho Posts: 16 Rating: (1)	Hello Guys, I have a doubt that is really confusing me. I was consulting the doc "S7-300 Module Data Manual" to know what does mean this parameter (Integration Time). According to it, this refers to the interference frequency to be suppressed. Ok In my case the line frequency is 60Hz, so I tried to use the mentioned parameter with the value 16.7, that is the related value in the manual. However, trying to use this value I can't get a satisfatory response from the analog module I use. It just work well when I use the other value (for 50Hz), 20. I just can't understand what is going on. I'm doing a documentation for an application and I need to explain which value should be used in each case. So I hope someone tell me what I am doing wrong. Thanks and best regards, Tulinho
tulinho Posts: 16 Rating: (1)
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6/29/2011 8:26 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (997)	I dont understand what your problem is...?
IBN-Service Posts: 8946 Rating: (997)
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6/29/2011 9:37 PM	Rate (0)
mralalog Regular Member Joined: 5/7/2010 Last visit: 8/6/2012 Posts: 13 Rating: (2)	"Integration time" with respect to an analog input module is the time that the analog to digital converter samples the input signal. Generally, one sets the integration time to the AC lineperiod of the locality. That will give maximum rejection of that interference signal. It is possible that you have interference nearer to 50HZ and the local 60 HZ does not interfere as much. In that case, I would set the integration time to 50HZ, 20ms, if that gives you a less noisy reading.

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6/29/2011 9:53 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/25/2023 Posts: 6822 Rating: (1349)	mralalog "Integration time" with respect to an analog input module is the time that the analog to digital converter samples the input signal. Generally, one sets the integration time to the AC lineperiod of the locality. That will give maximum rejection of that interference signal. It is possible that you have interference nearer to 50HZ and the local 60 HZ does not interfere as much. In that case, I would set the integration time to 50HZ, 20ms, if that gives you a less noisy reading. If you local Power lines carries 60HZ and you are concerned about the Hamonic ,their have different frequencies but their amplitudes are much smaller than their main signal. http://en.wikipedia.org/wiki/Harmonics_(electrical_power) Regards
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6/30/2011 2:58 AM	Rate (0)
tulinho Posts: 16 Rating: (1)	Mr mralalog, First I thought I should use the integration time for the period of 60Hz that is the frequency of the line. Once it didn't work of course I used the IT for 50 Hz. But what I still don't understand is why the module simply doesn't work at 60Hz period, I wasn't able to get any measure from the module, doesn't make sense at all this discrepancy be caused by harmonics in 50 Hz. thank you in advance, hoping for your help to explain me.
tulinho Posts: 16 Rating: (1)	Last edited by: tulinho at: 6/30/2011 3:14 AM
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7/2/2011 8:43 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (997)	tulinho Mr mralalog, First I thought I should use the integration time for the period of 60Hz that is the frequency of the line. Once it didn't work of course I used the IT for 50 Hz. ... Does not work? Hard to believe. No value? Wrong value? ???
IBN-Service Posts: 8946 Rating: (997)	Last edited by: IBN-Service at: 7/2/2011 8:45 PM
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7/2/2011 9:10 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/25/2023 Posts: 6822 Rating: (1349)	tulinho Mr mralalog, First I thought I should use the integration time for the period of 60Hz that is the frequency of the line. Once it didn't work of course I used the IT for 50 Hz. But what I still don't understand is why the module simply doesn't work at 60Hz period, I wasn't able to get any measure from the module, doesn't make sense at all this discrepancy be caused by harmonics in 50 Hz. thank you in advance, hoping for your help to explain me. May be it is an EMC issue.Consult the manual on how much intensity of magnetic field is permitted while working with an Analog module! Regards
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7/2/2011 10:06 PM	Rate (0)
tulinho Posts: 16 Rating: (1)	Believe me, when I set the integration time of the module to 16.6ms I just measure garbage, I can't even notice variations on the signal. But when I set it to 20ms it works well. One of my professors said maybe my CPU is configured to 50Hz and I need to work like if the line frequency was 50Hz. what do you think about it?
tulinho Posts: 16 Rating: (1)
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7/3/2011 1:20 PM	Rate (0)
IBN-Service Posts: 8946 Rating: (997)	tulinho Believe me, when I set the integration time of the module to 16.6ms I just measure garbage, I can't even notice variations on the signal. But when I set it to 20ms it works well. One of my professors said maybe my CPU is configured to 50Hz and I need to work like if the line frequency was 50Hz. what do you think about it? That makes absolute no sense for me. You can not "configure your CPU to 50Hz" If analoge signal is OK with filter 20ms but is wrong but with filter 16.6ms, something strange happens. Whatyour analoge signal is looking like? Can you do a scope image? It should be a (slowmoving) DC - signal. It is not possible to connect a real AC signal (i.e. 50Hz) to analoge input. Are there large disturbing signals in near area? Can you select 400 Hz (=2.5ms)?
IBN-Service Posts: 8946 Rating: (997)	Last edited by: IBN-Service at: 7/3/2011 1:23 PM
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