[jmccracken]

Has anyone repaired or replaced a Heidenhain encoder cable? Specifically, my encoder is an ERO 115 125.

Background: In a separate post, I've been outlining and discussing creating a 4th axis ... and my travails with adapting the encoder to work with my rotary table and my Heidenhain 151B. It now works! My latest task has been to build a jumper / internal-extension cable for the encoder, about 3-1/2 feet long, with a 9-pin Heidenhain female bulkhead connector so that I can remove my 4th axis - disconnecting it from the Interact via bulkhead connectors - and reconnect when I'm ready to use it again. The other end is an equivalent 9-pin male connector going into the controller.

Unbelievably, to me, I bought correct 9-pin connectors (they screw into controller and cable from encoder perfectly), I wired them per the attached print using shielded CAT 6 (four (4) twisted pair with shield), rung the jumper / internal-extension cable out with a multi-meter (continuity pin-to-pin, no cross talk or shorts), and - low and behold - the system doesn't recognize the reference switch when the jumper / extension cable is in place. By removing the jumper cable, and connecting the encoder directly to the controller, it works fine recognizing the reference switch.

What could be going wrong? Based on earlier posts, I'm assuming its somehow not getting the reference pulse through the extension cable - these are pins 7 and 8. There are no errors (gross or otherwise) indicating poor signal or loss of power to the encoder. The shield in the CAT6 cable is connected via pin 9.

Has anyone tried to repair a Heidenhain encoder cable previously and have any idea what's going on?

Thanks!

[Al_The_Man]

I have made up Heidenhain cables in the past with no problem, you don't have the two marker pulse leads crossed, by any chance?
Al.

[jmccracken]

Al ... your message encourages me! Thank you. I have wired the extension cable, pin-to-pin:

1 - 1
2 - 2
3 - 3
4 - 4
5 - 5
6 - 6
7 - 7
8 - 8
9 - 9

I'll recheck again. Do you agree that the problem just about has to be with the reference pulse, pins 7 & 8?

Thanks for replying!

[Al_The_Man]

Normally the motor moves until the switch is seen and then goes into slow until the encoder marker is seen and then registers this as zero.
Does your motor slow down at the home switch, or appear to look for the marker?
Al.

[jmccracken]

Al,

No to both of your questions. Without my extension cable, upon seeing the signal from the home switch, it will behave as you describe finding its zero without trouble. However, with the extension cable, it simply ignores the home switch signal. In other words, I've verified that the switch (normally open, so that upon the switch being made, the input as measured at the controller goes to +24V) when made, the motor does not slow or behave any differently.

Again, without the extension cable, it behaves correctly.

Thus, to your point, I assumed that it may not be seeing the reference pulse from the encoder (pins 7 & 8), but I don't see it slow appreciably at all upon the limit / home switch being actuated.

Thanks!

[Al_The_Man]

Check the encoder end of the cable and confirm you have 0v & +5v.
It is hard to check the signals at the control end because they are the low 11µa signal.
You would need a 'scope.
It does seem a puzzle if you have confirmed the connections all the way through?
Al.

[jmccracken]

Yes, I've confirmed connections by "ringing" (checking continuity) with a multi-meter, pin-to-pin and ensuring there is no cross-talk between pins. I have access to oscilloscopes, but I had hoped to not have to go to that extent.