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PTO Positioning Irregularities

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So I have a V130-J-TR34 driving a Teknic Clearpath motor via PTO. The motor is connected to a THK Ball Screw Slide with a Turck "Home" Sensor wired into the PLC via Digital Input.

The current program basically homes the motor/slide to the sensor, and then the sensor goes high, I then trigger an immediate PTO STOP, followed by a re-set of the PTO Profile, then finally a PTO Set Home. The Read Status Current Position is getting set to 0 correctly.

Then, if I do a PTO Move to a target (ex: 150215)...the PTO actually sends it to 150245, +30 counts. BUT, if I then move it back to home, it goes perfectly back to 0, and if I do the same move again to 150215, it goes exactly to 150215, and is fine thereafter moving to any position. (Counts also verified via Teknic Drive Software)

Is there some trick to configuring PTO in either the Profile or Move blocks that I might be doing wrong?


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  • MVP 2023

Maybe you must try to use Joe Tauser PTO Example for test

I think the problem is in activating the stop function in homing via sensor.

You system see sensor and decelerate.
After that you must to give the command to return to 0 and only then go where you need to go.



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Is there any logic occurring accidentally on the home sensors negotiate transition?


in getting the unit to stop does the home sensor remain on or does the slide actually move past the home sensor and end up re-triggering a piece of logic with an unexpected positive transition that it shouldn’t be during your first move?

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  • 3 weeks later...

I am having a similar positioning problem on my V130-33-T34.

Basically I have the same setup with a ballscrew set driving a motor trying to send it 4 different "PTO move" blocks to 4 positions on the linear rails. First I initialize it to a mechanic end switch - and give a "PTO Home" when it leaves it and it sets it right. I then proceed with absolute movements.

Then I give it a command to go to Target Position 1=100mm with 900rpm and stop with acc/ dec both 2.5 sec (2500 in ms). All good in positions up to here.

Then the fun starts, changing rpm in standing to 350 and acc/dec to 3000, Ihave to preform a movement where I give it a command to go to TP2=160mm, upon reaching the position I immediately give it a command to go back to TP3=120mm.

It reaches the TP2 and goes back to TP3 but I'm not sure if the actual movements are such and here's why.

I then proceed to go to TP4=2000mm which is actually just a bigger measurment than needed because after giving the command the program is checking for an induction sensor to give a signal that it is at the end of the ballscrew set. There it gives the command "PTO stop" in normal motion with dec=0.5s so it stops nicely and before the actual ending of the ballscrew.

After stopping at that position (around 370mm with maybe 0.1mm deviation) I give it a command to go back on TP1 with 900rpm and acc/dec 2.5s again.

When it arrives there the measurement from 0 position where PTO home was is 100mm which is okay.

After this there is another ladder net execution to turn an output on and off and after that it repeats the positioning startinf from TP1> TP2> TP3> TP4>TP1 with the same settings as in firat cycle.

The deviation starts when it reaches back to TP1 again, it is onl 92mm away from the 0 position physically, but the TP1 is reached okay and also the current position when it stops at TP1 is also the correct 100mm.

Each cycle gives 8mm less to actual position and so all the subsequent movements are off for that amount x number of cycles.

Should I just go to TP1 = 0mm and start from the mechanical endswitch everytime and go back to it at the end of cycle?


Thanks for reading, hope you come up on some solutions for me, I'll try to move it on 0 and reset it everytime.


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