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Calculate rate of change

Created by: Testermax at: 5/11/2011 8:22 AM (5 Replies)

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5/11/2011 8:22 AM	Rate (0)
Testermax Posts: 159 Rating: (3)	Hello! Im going to calculate the how much a weight changes every second, and accumulate this change, when a certain condition is met (comparator). I know two methods of accomplishing this: use the cyclic OB, or create an pulse each second. My approach was using the "onboard" pulsetrain in the PLC (1Hz) through a positive edge detection, to trigger this calculation (see the submitted picture) and run this in OB1 My question is, which method is the most precise and elegant, the cyclic OB or the timer in OB1? Attachment accumulate.jpg (825 Downloads)
Testermax Posts: 159 Rating: (3)
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5/11/2011 8:50 AM	Rate (1)
Chilly_Garfield Posts: 316 Rating: (37)	Hi Testermax, I think the best and most elegant methode is to use the OB 32 (cyclic interrupt every secound). With this OB you can absolve the processor occupancy rate and need no cyclic timer, pulsetrain or comparison.
Chilly_Garfield Posts: 316 Rating: (37)
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6/6/2018 4:39 PM	Rate (0)
ohsix Posts: 1 Rating: (0)	Testermax, I know I'm bringing this post back from the dead but I need to accomplish the same thing as the you using Step 7 v15 and I'm wondering which method you went with and how well did it work?
ohsix Posts: 1 Rating: (0)
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6/7/2018 9:45 PM	Rate (0)
marianosk Posts: 1 Rating: (0)	Read the last OB1 cycle time in milliseconds every cycle, store it in the marker as real or int and use it in your calculation with increment every cycle. That's the highest precision what you can get.
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6/13/2018 5:26 AM	Rate (0)
Freewhere Posts: 9 Rating: (0)	You can create the program in cyclic interrupt OB block and define the cyclic time
Freewhere Posts: 9 Rating: (0)
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6/13/2018 7:51 AM	Rate (0)
mopS04 Posts: 5521 Rating: (1058)	hi, I also think the best solution is to use an cyclic interrupt-OB with 1000ms call-time. this is more accurate than the solution in OB1. regards,
mopS04 Posts: 5521 Rating: (1058)
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