Need help w/ Ultra 3000

I am having a nagging problem with an Ultra 3000 servo. The problem I am having is the servo will be sitting in a dwell position and lose the axis homed input from the drive. I did a histogram on the PLC and it drops out for just .05 sec and comes back on, but by this time my PLC instruction for the servo axis homed has dropped out. The funny thing is it doesnt happen all the time.

All of the Hardware has been changed (drive, encoder cable, and motor) and we have tried the program from the other unit that is the same with no different results.

Dirty power maybe. Had a similar issue machine was close to bank of welding power supplies. I ended on installing power conditioning filter for control lines. Also a reactor was installed before the drive. No problems since.

pjones411 said:

.... I did a histogram on the PLC and it drops out for just .05 sec and comes back on, but by this time my PLC instruction for the servo axis homed has dropped out...

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If that time (.05 seconds) is repeatable, an easy temporary patch might be a timer in the PLC, to "debounce" this signal...only do this if it poses no other risks...

Paul

Pjones, I had this exact same problem with an Ultra a few years ago. I tried using a debounce timer as Okie suggested and this seemed to help but not all the time. Sometimes the signal would just drop out for a fraction of a second, but other times it would drop out and "stick" off--as soon as I touched my meter leads to the terminal, it would come back on. You may want to experiment with adding a pulldown resistor to prevent the output from floating when it is off... this helped in my situation.

I currently have a debounce timer in the PLC program. I has worked thus far. I will try the resistor if the problem appears again. Thanks for the help guys.