conveyor speed-flow rate using incremental encoder and load cell

AMAZINGAHMED

Member
Join Date
Jul 2005
Location
Cairo
Posts
101
Hi 2 all

I had that project some time ago where i needed to calculate the conveyor speed. I have an incremental encoder 360ppm attached to the driven drum. i had Siemens s7-313C cpu.
What i did is to utilize OB35 (cyclic interrupt) to calculate the pulses difference every 100ms. Then i measured the drum diameter (d1) to get the linear distance moved for 360 encoder pulses (linear distance=pi*d1 = 0.68m). Then i calculated the conveyor distance moved in the last 100ms using: (distance=pulses difference*0.68/360) m/msec. then i multiply by *10*60 to get m/min.
Am I right so far?
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Now to the flow rate portion:
I have a load cell and i read the weight using a SIWAREX card which gives me the current weight in grams.
The effective weighing distance will be that distance between the two rolls before and after the load cell roll (d2=0.85m).
I divided the current weight by 1000 then by 0.85 to get the weight per distance Kg/m.
The final step is to multiply Kg/m by m/min to get Kg/min which is the flow rate then i changed it to Ton/hr.

I wish i'm not out of the track
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Finally i needed to have a totalizer to calculate the total material passed through the conveyor:
i calculated the encoder pulses which equals 0.85m using: (encoder pulses for 0.85m= 0.85 * 360 / 0.68 =450 pulse).
I then every 450 add the current weight to the total weight.

I saw to share my experience with whom interested because like all the people on this forum i like to help and also if anyone has other ideas for such calculation or sees that my method is wrong, please share.
Good luck
 

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