Msorich

First, EQN it's not standard at all, it just first three letters of type Heidenhain's encoder 25 bit res +12 bit multiturn capacity, meaning 33554432 ppr and 4096 multiturn part.

Looked through its data, I learned that feature of safe information operates within its singleturn part. It's written in black & white there. This means within 33554432. Absolutely the same writes Siemens for their encoders and the same I wrote you above.

I have no clue where did you get "1/2 of multiturn part issue".

If you have issue you-called "beyond 1/2 of multiturn capacity", I would suppose that youre Drive, so to speak, operates is not in harmony with encoder. Because there shouldn't be any problems within singleturn resolution, which is much much far beyond 2048.

Considering that Heidenhain encoders have pretty high resolution by wide known reasons and as I wrote you above try to adapt encoder via p400 [9999], so-called "user defined encoder".

Hope this helps

Msorich

 

I do not have any encoder... I was simply reading the question at the top of this topic and read the official response from the "Tech Team" and they brought up the issue of "1/2 of multiturn part issue". 

If you read the original question to this thread and the response just after it from "Tech Team" they state the following:

"1)When drive is completely shutdown (no power or control voltage) only your real multiturn of the encoder is relevant. When drive is powered off and you manually move it > than 1/2 multiturn (4096/2 = 2048) the drive has after power on again a false position."

That statement by "Tech Team" is what made me start researching this "half multi-turn" issue.  I'm done with this issue because I think I understand what they meant by their statement.  I was just being courteous to you and tried to explain what I learned since you spent some time to try to help.

I think you are getting too caught up with the details to see the big picture.  An absolute encoder is called an absolute encoder because it does not require power to track its position.  A single turn absolute encoder can only keep track of position within one rotation and a multi-turn absolute encoder can keep track of its position within multiple rotations.  If you told me an absolute encoder could not track its position without power, then I would call it an incremental encoder and not an absolute encoder.

It does not matter whether it is a single turn absolute encoder or multi-turn absolute encoder, and it does not matter whether it is a 12 or a 13 bit multi-turn absolute encoder... the idea is the same regarding manually moving the encoder greater than half a multi-turn when power is off.  If you rotate beyond a half multi-turn, the value presented to the controller by the multi-turn bits of the encoder will not reflect whether the encoder was rotated clockwise to get this this value or counter clockwise.  If you rotate less than half a multi-turn, the value presented to the controller is unique within the range stored by the controller and the controller knows exactly where the axis is and whether it turned clockwise or counter clockwise.

Here's one last way to help you understand how I think it works. Assume you had a 12 bit multi-turn absolute encoder (12 bits meaning 2^12 = 4096) capable of tracking 4096 rotations before rolling over to zero. If you exaggerate the scenario and rotate the encoder shaft a full multi-turn (half a multi-turn x's 2), or 4096 rotations with the power off, then the value after rotation will equal the same exact value before those 4096 rotations.  Since it is the same value, the controller upon power up will think the encoder has not moved, when it in fact moved a tremendous amount and the ball screw slide is 5 meters away from where it used to be.  Just as this is a problem when rotating the encoder shaft a "full multi-turn" (or 4096 rotations), similar problems occur any time you rotate beyond a "half multi-turn" when the power is off.

I hope I'm right and I hope this helps... Thanks

F07443

F07443