[Teejaycasa]

Hello everyone,

I'm experiencing an issue with a Heidenhain 155 CNC, the problem is with Z axis.

After switching on the machine, the reference of Y axis is done correctly, but for the Z axis, it continues moving even after reaching the reference point cam and the machine stops when the axis reaches emergency stop.

I checked all the hardware side, everything seems OK.

Do you think that it can be a software issue?

Could someone help?

[gridley51]

Have you just entered or changed the parameters?

[Al_The_Man]

Not seeing the encoder marker pulse?
Trip the home limit well before the end of the stroke and see if it references?
Al.

[Teejaycasa]

The machine was recently purchased by of friend of mine, he got it from Belgium, this machine has never worked after its installation on his site.

I tried to trip the home limit as Al The Man said but same issue.

I guess that it is something related to parameters

[Al_The_Man]

If it is the same issue with premature tripping of the limit may point to not seeing the marker pulse?
Does it continue on to a hard stop O.T.?
Al.

[Teejaycasa]

I tried also to replace this switch with a new one, same issue.

sorry Al do you mean by O.T the emergency stop limit switch?

[Al_The_Man]

If you trip it prematurely and it keeps on going, it is either the home switch or if not then it is the encoder reference pulse is missing.
If it sees the switch it should go in to low rpm.
Al.

[Teejaycasa]

I did another experience.

Swiched off the machine, I removed the cam box which holds the home & emergency stop switches. I pushed the home switch premanently, started the referencing: the axis moves downworads, when I release the home switch it moves upwards. but when I push the same again the axis doesn't stop and continues to move.

If the encoder pulse is missing maybe we get an error like the famous "Gross positi errr"

[Al_The_Man]

The missing marker pulse is only once per rev, it would not show position error.
It looks like the marker is missing.
Al.

[gridley51]

It is not necessarily the marker pulse missing.It can also be the reference switch changeover is too close to the index pulse.Recently had that problem with a new encoder and I had to use a scope to prove the index pulse was there but was happening at the same time as the reference switch was changing from ignore the index pulse to look for the index pulse.Turning the encoder half a turn cured that one.
Canteuse (sp)? who posts in one of the other forums here had the same problem with the axis running away after hitting the reference cam and the problem was his parameter for counting direction for that axis was wrong.I can`t exactly remember now but he will tell you if asked.

[Al_The_Man]

It is not necessarily the marker pulse missing.It can also be the reference switch changeover is too close to the index pulse.Recently had that problem with a new encoder

But he mentioned it did it when tripping the LS manually as well?
Al.

[gridley51]

But he mentioned it did it when tripping the LS manually as well?
Al.

Al,I know but I had the same problem and tried tripping the LS manually and still it wouldn`t reference.
I had put a brand new encoder on a mill with a 155 and it worked fine for three months then wouldn`t reference on the Y.Exact same fault as described.
Complained to the encoder vendor who said check it with the scope and he was right,the pulse was there.Then swapped cards out of the control,still no difference.unclamped the encoder and rotated it half a turn,perfect.
Canteuse who I referred to emailed me looking for help with the same problem.He had just loaded parameters.One of the encoder parameters was wrong.
I had this problem three times on Heid controls.

[cantause]

Hi everyone,

As Mark said, he helped me out with a problem very similar to the one Teejaycasa is talking about.
In my case, I 've had to reenter the parameters after a power loss, but I only had a universal set from the manufacturer, not a back-up, so some parameters needed modifications.
My referencing problem (X axis hitting hard limit switch) has been solved by changing the parameter for counting direction of that axis.
If Teejaycasa has the same kind of problem, he might try to switch the value of the counting direction parameter for the Z axis (MP22).

I hope this can help, this solution was found by Mark, he's the one to thank if it works :-)

François

[underthetire]

This machine use heidenhein scales as well?

Ive seen those scales with a little magnet on the top housing. The magnet does fail (seen 3 of them go so far) and replacing them fixed the reference problem.

[Teejaycasa]

Thank you all for your answers.

I will try the two solutions:

1. Rotate the encoder a half turn;

2. Modify the MP22 (0 or 1 as shown on the service manual), but plz how to get to the parameter menu, is there any special code?

NB: this machine doesn't use scales as per underthetire question.

[Teejaycasa]

Please could you plz show me how to access to parameter menu, I can't find that on the manual.

[gridley51]

Please could you plz show me how to access to parameter menu, I can't find that on the manual.

Switch the control on.
Keep pressing the MOD button until it asks for Code Number.
Type in 95148 and press ent.
Parameter list will come up.
Use the Up Down arrows to get to the parameter you want to change.
When the parameter is highlighted type in your value.
Arrow Up/Down to the next parameter.
Press DEL twice to exit parameters.

What make/model of machine do you have?

[Teejaycasa]

Many thanks, sorry for my late reply, I was too busy last days.

I will try this and let you know.

The machine is HURON, model: SXB 523, MY: 1989