Z Measuring System Defective A

[pjeran]

Got a new error message that I can't find in the manuals that I have.

I am running an Interact 1 Mk 2 w/ a 151 control. Went to power up the machine, it cycled through the x,y,z axis OK, but when I try to use the hand wheel or Z axis feed, a relay trips and the screen reads:

Z Measuring System Defective A

Anyone know what that means and where to start looking. I have a bad feeling the bulb in the encoder is starting to go.

Any thoughts?

Thanks,

Paul

[machintek]

A measuring system defective is just what it means. It could be a cable, a plug or the device itself. Since it does home and only occurs when you switch to the handwheel, it may be indicating that the handwheel encoder is defective. What happens if you use the Z joystick?

George

[pjeran]

George,

Thanks for the quick follow-up.

It will happen using either the joystick or the hand wheel. It does not happen immediately, the first time it happened, I had been able to touch off on the x and y axis for a part and I was touching off on the Z with the hand wheel when it tripped. The next time, I was just moving the Z using the joystick and it tripped.

Any other suggestions would be helpfull.

Paul

[machintek]

Swap X and Z or Y and Z motors. If the problem follows the motor, you have your answer.

George

[pjeran]

George,

Finally got a chance to swap the servos, Z for X. Unfortunately, it did not follow the servo, still getting the Z measuring system defective A error. The X axis worked fine.

I have found that if I manually move the spindle down and then start up the machine the Z will home, but then when I try any movement either with the dial or the levers it will error out, sometimes it is instant, other times it takes a second or two.

Any more thoughts?

Thanks,

Paul

[gus]

That proooooobably tells you it is the wiring to the motor encoder.

[pjeran]

Gus,

When I swapped the servo I swapped the cable too. I am now wondering if it is something in the 155 control. At a loss right now.

A while back I lost all the parameters due to the battery dieing and used a set from a friend with the same mill. Is it possible that one of the parameters not being tuned could cause this? The mill has worked for the better part of a year with the new parameters.

Thanks,

Paul

[machintek]

I do not believe it is the parameters. They are generic with the exception of travel limits and backlash. Drive tuning is done at the servos.
Heidenhain has a procedure that allows you to use the handwheel encoder plugged into a axis encoder control input to check that part of the control circuit. Call Heidenhain and see if that test leads you to any conclusion.

George

[pjeran]

Thanks George I will give them a call.

[gus]

Unless you tapped into the back of the machine directly to the encoder with new wires, it could still be a wiring issue. One piece at a time, you have eliminated the servo/encoder, so wiring is the next issue, then the control itself.

I'm trying to think, it occurs to me that there is a situation where I can get an encoder error without an encoder error, maybe if the parameter is backwards or something, but I cannot think of it.........or maybe I am imagining it.......

[pjeran]

Just thought I would post a follow up for anyone else that might run into this problem.

It has taken a while, but I traced and reseated every connector in the encoder path, swapped servo/encoders and the problem still existed. Cleaned all the contacts going into the controller.

While reading through the controller manual I noticed that they were talking about multiple boards in the controller. Seeing that I had addressed everything external, decided to take a look see inside the brain box.

Made sure I had all the parms written down and pulled the brain. After I opened up the top, I was surprised to see that after using such a bomb proof connector on the outside of the controller for the encoder, the internal connection is a simple molex connector. Pulled that board and the connectors cleaned all the contacts and reassembled.

Crossed my fingers and fired it up. Success!

I hate intermittent errors. Just a note to others, the controller is not hard to remove or work with.

Now back to making chips!

Paul

[gus]

thanks for the follow up, it is always good to hear the answer, and this on especially because it is not one I would have thought of.

good job following through logically, most probelms are simple if approached correctly