Encoder Pulses to Distance & Speed

whussain6

Member
Join Date
Oct 2013
Location
Newcastle
Posts
108
Hi, I am sure it must be simple but my head is not working at the time.

I have
- Encoder pulses (Input)
- Pulse per Rev of the belt
- Belt circumference (mm)

mm_per_rev = (Belt circumference/PPR)

I am calculating distance d (m) = (Pulses) x mm_per_rev/1000

Question is how to calculate the speed?
I must have all this within AOI so cannot use time based routine to calculate the speed. But ms pulse is provided for AOI.

it must be something like
d2 - d2 / t2 - t1

what about rollovers etc.
Appreciate your help.
 
Speed = [distance traveled during last elapsed time] / [elapsed time]. If you calculate for example velocity every 5 seconds, then the velocity in m/s will be just the traveled distance divided by 5.

Rollover : if the total distance is for example >= 100000 then subtract 100000, then the traveled distance will be negative and to correct it just add 100000
 
Convert Speed units per scan speed to per second

Actually I am looking to convert speed units per scan which I am obtaining from differential distance to speed (m/s).šŸ™ƒ
 
To obtain a stable speed reading you need a precise time base, and the scan time of a PLC is not usually stable.

In addition you need to count an appreciable amount of pulses between measurements, I think there should be at least 50 pulses
 
To obtain a stable speed reading you need a precise time base, and the scan time of a PLC is not usually stable.

In addition you need to count an appreciable amount of pulses between measurements, I think there should be at least 50 pulses

If you put your speed calc code in a Periodic Task the scan time base will be precise. We do it all the time.
 

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