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Calculate machine speed with absolute encoder

Created by: Eng.Mahmoud at: 10/22/2012 2:24 PM (7 Replies)

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10/22/2012 2:24 PM	Rate (0)
Eng.Mahmoud Advanced Member Joined: 12/20/2009 Last visit: 9/13/2021 Posts: 6 Rating: (0)	Hello everyone, i have an application where i need to calculate the speed of a machine as a Rev/Min.and then to get this speed to set the speed of another machine as they are synchronized togrther.i have a profibus absolute encoder which i use in cam control and it works ok.but the problem in the machine speed calculation.so any one have a solution? my hardware is cpu 314C-2DP and profibus encoder 6FX2001-5AP25 thanks

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10/22/2012 4:49 PM	Rate (1)
daad Silver Member Joined: 10/31/2011 Last visit: 11/26/2024 Posts: 400 Rating: (5)	Dear Mahamoud, You have to measure number of pulses for one revolution.Then mesure number of pulses for one minute(according to percesion) then divide these pulses to number for one revolution.And reset the number measured counts. So that is one of the method for rev/min Regards

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10/24/2012 10:08 AM	Rate (0)
Eng.Mahmoud Advanced Member Joined: 12/20/2009 Last visit: 9/13/2021 Posts: 6 Rating: (0)	Dear m.shoaib khatana the idea you said i used before with incremental encoder and it works fine. the difference here the the encoder reading is by degreee,so it read from 0 to 8192 pulse/rev then it resets and start from 0 again. the other thing that i need much faster calculation (max 500ms) as i will use this valve in a pid function thanks

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11/14/2012 10:21 AM	Rate (0)
ozi Bronze Member Joined: 3/24/2006 Last visit: 11/17/2024 Posts: 58 Rating: (13)	what is the maximum speed of rotation ? if its not fast enugh you can use this 8000 pulseas modulo and find diffrenses in a timer interrutp OB35 for example... you can also also change interrut time for beter calculation

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3/21/2013 1:57 PM	Rate (0)
alvis Posts: 4 Rating: (0)	Hello, my situation is similar. Can You explain your solution in more details? Thanks
alvis Posts: 4 Rating: (0)
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3/23/2013 6:35 AM	Rate (0)
ashishm Bronze Member Joined: 2/1/2011 Last visit: 9/13/2023 Posts: 186 Rating: (4)	Dear alvis, The solution provide by ozi as per me is correct. you calculate the difference in present and last value of encoder in OB35 which gives you about difference in encoder value for 100 ms so Indirectly you are getting speed for 100 ms that you can calculate by this for Minute which can be used as RPM.

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3/25/2013 8:26 AM	Rate (0)
magdykh_fee Regular Member Joined: 3/25/2013 Last visit: 7/11/2024 Posts: 1 Rating: (0)	you can easly get the speed , firist compare between the cuurent value and zero , when equal set marker (M0.0) and when equal the maximum value for encoder reset the marker (M0.0) then make this marker to operate a timer,,,, then move the cuurent value of timer at negative egde of the marker (M0.0) this value represnt the speed of the motor

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7/21/2015 11:08 AM	Rate (0)
RIAN Che Bronze Member Joined: 1/2/2014 Last visit: 11/10/2024 Posts: 148 Rating: (22)	magdykh_fee you can easly get the speed , firist compare between the cuurent value and zero , when equal set marker (M0.0) and when equal the maximum value for encoder reset the marker (M0.0) then make this marker to operate a timer,,,, then move the cuurent value of timer at negative egde of the marker (M0.0) this value represnt the speed of the motor Hi expert , can you explain how that timer value represent motor speed? I dont understand? Can y ou explain?

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