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Use of a compter of S7-300

Created by: Draxelmaier at: 11/24/2006 9:05 PM (16 Replies)

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11/30/2006 11:56 PM	Rate (0)
Draxelmaier Posts: 27 Rating: (0)	Hello Wizard, Finally I could installed the examples requested, I decided to use function SFB47 COUNT and not that of measurement of frequency because function SFB47 is used more for this type of applications. My problem now, which is the best mode usable of hardware configuration of theencoder for my application to calculate speed from an incremental encoder (24VDC, A/B)... continuous, periodic,... Also the evaluation of theinputs of counting: Impulsion/sens rotary simple coder rotary double coder... Thank you...
Draxelmaier Posts: 27 Rating: (0)
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12/1/2006 9:30 AM	Rate (0)
Wizard Diamond Member Joined: 4/24/2006 Last visit: 12/3/2024 Posts: 8777 Rating: (1172)	Hello Draxelmaier, When you use Continuously counting, if the countvalue will reach the upperlimit it willgo back to lowerlimit and counts up. If you use Periodic counting,if the countvalue will reach the upperlimit it will go back to theLoadvalue and counts up. So I think perhaps the periodic counting will be best. Then the evaluation of pulses, you can count only the positive edge of signal A (single), or you can count the positive and negative edge of signal A(double). Or you can count positive and negative edge of signal A and B (Quadruple) It depends how secure you want to be. Best regards, Wizard

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12/1/2006 7:50 PM	Rate (0)
Draxelmaier Posts: 27 Rating: (0)	Hello I understood the modes of counting well. Thank you… Another question, during the counting of the impulses of the encoder, i.e. considering the periodic stopping of the encoder,is the zero setting of the current value ofcounter COUNTVAL is automatically done with each cycle counting. Thank you.
Draxelmaier Posts: 27 Rating: (0)
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12/3/2006 12:21 PM	Rate (0)
Draxelmaier Posts: 27 Rating: (0)	Hello During the use of function SFB47 COUNT, How to detect the stop of counting, i.e. when the current value ofcounter COUNTVAL remains constant, because at this time speed must be null. Thank you...
Draxelmaier Posts: 27 Rating: (0)
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12/4/2006 2:07 PM	Rate (0)
Wizard Diamond Member Joined: 4/24/2006 Last visit: 12/3/2024 Posts: 8777 Rating: (1172)	Hi, When you want to use Periodic counting, the countvalue will fall back to load value when it's value reaches the UpperLimit. It's difficult to recognize there are no pulses anymore. In that case you'll have to read out the Actual Countvalue at certain periods and compare with an old value. Perhaps it's better to use Frequency measurement. Best regards, Wizard

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12/5/2006 12:01 AM	Rate (0)
Draxelmaier Posts: 27 Rating: (0)	Hello To use the function of measurement of frequency, starting from the value of frequency provided in mHz. I have an encoder of resolution 200 impulses/turns. The suitable time of integration is of 400ms which corresponds to the suitable base of time for the calculation speed. My question is Calculated speed is Speed = (MEAS_VAL * (60/200))/1000 out of Turns/min? With 60: conversion of second into minute, 200: resolution of the encoder, 1000: conversion of mHz into Hz. Thank you...
Draxelmaier Posts: 27 Rating: (0)
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12/5/2006 1:57 PM	Rate (0)
Wizard Diamond Member Joined: 4/24/2006 Last visit: 12/3/2024 Posts: 8777 Rating: (1172)	Hi, Just wondering: Speed = ((Measured value * 1000 * 60)/ 200) turns/minute Hope this helps. Best regards, Wizard

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