DSP upgrade for Shenhui laser one last problem

[Frasmet]

Howdy All!

I've finally got this upgrade completed, software installed, everything grounded, etc. There is only one problem that i can't seem to resolve.

At power on and when hitting the reset button the laser races toward the machine zero position and does not stop. It will slam itself into the upper left as hard as it can until I hit stop on the control panel. Several screws un-threaded themselves and I had to re-thread the holes and replace all the screws on the laser head (but everyhting is now tight and square). I have been forced to power on the machine with the stepper controllers disconnected and after the resetting connecting them and moving the head to the proper origin point via the control panel. Please note that when cutting the laser head returns to the correct position and moving the head by either computer control of control panel it stops exactly where it is supposed to.

Any thoughts or advice would be appreciated.

[Toasty]

Probably a silly question, but do you have limit switches wired up? I didn't see any mention of them in your post.

I would say either no limit switches or the limit switches are wired incorrectly.

[Tech_Marco]

First thing to do, check the limit switches with continuity tester.

Before power up the system, move the laser head to the center of the XY stage. Power up and manually trigger the XY limit switch and observe the XY reaction. Note that it take 3 triggering on the limit switches to simulate "HOME" and stop XY from moving. So, let's say you tap Y limit switch first, than the laser head should stop Y movement but will move along X direction. Once it happened, tap on X limit switch and the laser head should stop X movement but will move to the Y (home) again. Now, tap on Y limit switch again and the laser head will finally stop (Home).

During the above simulation, observe if the X,Y respond correctly. I did run into a trouble when I was retrofitting one of my machine. The XY limit switch seems working properly as the DSP controller sense the signal. But the laser head bumping the HOME even though the XY limit switch were triggered. I was pulling my hairs but still couldn't image how it could happen. After spending 1hr for diagnostic check and I got the solution. The problem was: X Y motor driver reversed!! So, X limit switch was set to Y motor while Y limit switch was set to X motor.

Always pay attention to the wiring.


Marco