Problem with PTO

[Mabrill]

Hi everybody

We have a problem with a PTO we use this to control a servomotor, in a bag maker machine, but when we use a sensor to stop it the PTO this take a little time to stop, then the machine stop few centimeters after the signal has been received. And when we increment the frecuency (speed) the distance of stop becomes higher. Somebody have any solution?

[Emil]

Hi,

Such reaction is "normal".

If you give PTO target, it will stop immediatelly when it reaches the target.

If you Reset RUN bit, it's operated at te end of the scan, so some delay is expected.

What yo can do to improve te reaction:

1. To read immediate the input (Read Physical inputs - VisiLogic > More menu > Immediate) within 1.25 ms (Enhanced models) or 2.5 ms (all Vision PLC).

Or:

1a. Connect the sensor to HSC (reload) and give it Target = 0. When the signal comes, the congtroller will enter immediatelly in a dedicated subroutine.

In Interrupt subroutine, SET one "Stop" MB/XB.

In the normal scan, each few nets add a net "When "Stop" bit active - reset it and jump to End.

With this procedure the reaction time of thhe congtroller will drop from up to 2 scans to few ms or even few tens of microseconds (option 1a with enhanced models).

Please let me know if you need more help...

[Damian]

Hi everybody

We have a problem with a PTO we use this to control a servomotor, in a bag maker machine, but when we use a sensor to stop it the PTO this take a little time to stop, then the machine stop few centimeters after the signal has been received. And when we increment the frecuency (speed) the distance of stop becomes higher. Somebody have any solution?

Not sure what exactly your doing, or what you hope to achieve, but it sounds like you are performing a simple "registration" type move. In these types of systems the sensor is not meant to stop it immediately. It is normally setup with an offset between the sensor and the actual desired stopping point. This gives the servo some distance to make corrections and ability to decelerate to a controlled stop. This would also make the stopping point non-speed dependent (within reason).

I think for us to provide you with better suggestions you will need to better explain exactly what your system is and what your expectations are.