Interact Encoder Scaling Factor - 4th Axis

Hello all ... I finally finished building a 4th axis for my Bridgeport Series I Interact w/ Heidenhain 151B controller using an extra SEM servo motor and encoder (same as the X, Y, and Z axes). All I lack is to get the scaling correct. For instance, moving the 4th axis 90-deg (command line: G01 G90 A90) moves the rotary table, in reality, 144-deg.

I have played with a number of machine parameters but nothing seems to change scaling, including the "correction factor" parameters, MP43 specifically.

How can I adjust scaling?

Many thanks!

For angle measurement (with axis IV) rotary encoder types ROD 250 and ROD 700 with 18,000 lines are available.

there should be an encoder count parameter for the 4th axis [and every axis]

hmm. but I do not see one, there is parameter 15 which would change interpolation from a factor of 20[value 1] to 10[value 10]

perhaps the newer controls have the parameter I recall

Gus - I agree that there should be some sort of proportional control on any P - I - D (proportional - integral - derivative) controller. MP28 - 31 is the integral values for each axis, and MP 32 - 35 is the differential values. MP12 - 15 seems to be the only value that corresponds to proportional. Changing my MP15 from 0 (20-fold) to 1 (10-fold) does change the result ... it now moves over 200-deg. for a 90-deg. input. This is encouraging in that it appears that you're right ... the MP15 value should be adjustable to something like 25-fold for my application.

csg67 - perhaps you're right as well. I find it interesting that 90 / 144 = 5/8 ... and exact fraction implying that I need 8/5 more counts to make it work correctly for my application. How many counts do the standard Heidenhain encoders have (I don't have my model number handy right now)?

Are there multiplyers (some sort of signal conditioner box) available? Perhaps I can get into the actual programming of the Heidenhain 151 (see this link: http://igor.chudov.com/manuals/Bridg...escription.pdf) that allows me to custom set my "signal evaluation" as given in MP15?

Thanks!

TNC151B controller can be used only in special encoder.
The MP12-15 values ​​only '1 '(20 fold) or '2' (10 fold).
Replace the electric motor at the end of the encoder, or change the mechanical ratio. :)

See the "Installation and interface description"
http://content.heidenhain.de/doku/om...B6/N140B6.html
2.3.3.2 Transducers and EXE-units for axis IV

The encoders with 18000 and 36000 lines must be used.They must be 11ua output type.
As other people have pointed out,it`s quite plainly written in the Heidenhain manuals for the control and applies to all 100 series Heid controls.

Ok...for comparison how many lines do the standard encoders have? I believe that mine are ERO 115-125 encoders.

The 125 means, I believe, 125 lines or pulses per revolution. My axis moves 144-deg for a control of 90-deg. That's 8/5 exactly. So I think I need an encoder with 8/5's the pulses per revolution. 125 x 8 / 5 = 200.

Thus I need an ERO 115 200 on the end of the motor, or, as others have pointed out, a ROD 250 having 18000 lines / pulses per revolution mounted direct to the rotary table.

My rotary table is a 90:1 ratio ... 90 x 200 = 18000. The Heidenhain controller wants 18000 pulses per revolution of the table whether the encoder is on the motor or direct to the rotary table.

From other threads its apparent that the Heidenhain encoders are 11-microamp sinusoid all encoders.

The way around it would be to gear the encoder.May be possible but then you need to get it to ignore the index pulse when it`s not required and take care of the backlash.
All the manuals are freely downloable from Heids website.
You can configure encoders individually once you get to the 355 control and possibly the 2500.

The reference point is really a problem, see # 6 link:
3.6 Inputs "Reference end position" and "Reference pulse inhibit"

Backlash compensation IV: MP39.

Well ... I finished making and installing a bracket for relocating the ERO-115-125 encoder and stepping it up by 8/5 such that it is now providing 200-pulses per revolution of the motor. Attached is a screenshot of the SolidWorks drawing of the encoder relacation bracket.

The result is that the 4th axis now works perfectly!

Thus far I haven't had to deal with any issues resulting from the encoder pulse occuring more than once per motor revolution ... but there is still plenty of time to get frustrated again.

Alright ... I'm super frustrated again. 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.

Unbelievable - 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, and - low and behold - the system doesn't recognize the reference switch when the jumper 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 now? Based on earlier posts in this thread, 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.

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