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How to read analog input with certain sampling rate and number

1/5/2011 3:27 AM	Rate (0)
ossoo Posts: 8 Rating: (0)	Hi everyone, I am using S7-200 with EM231 (8 AI) module. I need to read from an analog input channel at certain sampling rate and number, like read 40 samples every 250us since A/D conversion time is 250us. Then I need to do calculation based on these 40 samples. How could I do to acheive this? I am new to PLC programming. Please give me detailed information. I'll appreciate a lot. Thanks,
ossoo Posts: 8 Rating: (0)
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1/5/2011 2:28 PM	Rate (0)
Darius Platinum Expert Joined: 9/28/2005 Last visit: 7/24/2025 Posts: 2957 Rating: (243)	Hello, I don't think that you can use any interrupt that can handle reading at 0.25ms rate. That's just too fast. Minimum time that can quearantee you fixed acquisition is 1ms with S7-22x CPU. So you should think about other sollution.
	Best regards, Darius
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1/5/2011 7:40 PM	Rate (0)
ossoo Posts: 8 Rating: (0)	Hi Darius, If I use 1ms per sample, how should I program to achieve this? Since I am new to PLC, I have no idea how to do it. Thanks,
ossoo Posts: 8 Rating: (0)
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1/7/2011 8:12 AM	Rate (0)
Darius Platinum Expert Joined: 9/28/2005 Last visit: 7/24/2025 Posts: 2957 Rating: (243)	Hi, I don't think its not good idea to teach you to program PLC in the forum. Please start with the S7-200 system manual and as detailed questions then.
	Best regards, Darius
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1/7/2011 8:49 AM	Rate (0)
Marcjan Platinum Expert Joined: 4/22/2010 Last visit: 3/31/2025 Posts: 5697 Rating: (716)	Also the Tips and Tricks can be a great help to understand the 200 series: https://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objid=1232912&caller=view
	Problem solved? Please let us know! Please no technical questions by PM, use the forum sections for your questions.
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