MicroLogix 1500 issue! 2

[jrush01]

Hey Guys!
We have a Laser Molding Robot Machine with MicroLogix 1500; 24BWA AC Power, MC206 Motion Coordinator and PanelView 550 screen. I have an issue with its Home Position. Machine is supposed to mold shoddy onto a plastic base while checking for color and clips. Whenever the Emergency button is hit, and the machine is turned back on; the machine considers that last point of operation as it's Home Position. When you set it to return Home position, it moves around and stops at the point where the Emergency stop button was applied. Is this a memory glitch?? How do i get it to return to its actual Home Position?? I highly appreciate and welcome any input.
Thank you.
~Jrush01!

 

[ADMIRALKEN]

Has it every worked correctly?
Sounds like you need to write a homing routine in the logic.
On first pass or after E-stop, have the homing routine run.

Or it could be that the system is/was setup with absolute encoders, and someone replace the encoder with the wrong part.

 

[jde777]

Sounds like it is working properly. If the machine was in the middle of forming a part and e-stop is initiated, I would expect the programmer to write code to pick up where it left off, not restart from the beginning. I would upload program from the controller and review the code written for the e-stop and position.

 

[jrush01]

Thanks Admiral and jde777!
Yes, the Machine is working properly, and i understand what jde777 is saying in that the machine should pick up where it left off. Problem is; after it finishes molding the part in which the e-stop was initiated,and the cycle is finished, when you put a new base and shoddy for molding; you should be able to call the machine to it's original home position for a new cycle; but instead, it considers that point at which the e-stop was initiated "home" from then onwards. I need to be able to reset it back to it's home position.
Hopefully this will help explain my problem a bit better.
Thanks again for the inputs and ideas!
~John!

 

[jonesy29847]

Some servos look for a home pulse from the encoder. The pulse will occur once per revolution of the encoder.

In a past life I would return the servo to a known position, using a limit switch, then issue the home command, the servo would move in a direction I would specify until the Z pulse the the servo would stop and be homed.

The documentation for the servo should be helpful.