Heidenhain encoder questions

Got a new to me 1987 Bridgeport Series 2 Interact 2 mill with Heidenhain
151 controller. Machine was made in England. Servo motors each have
an encoder for the DRO in addition to the tach for motion feed back. Also
has an MPG encoder for axis jogging. The Heidenhain books give very little
info on the parts they use. The plan is to update the servo drives with
something that will take step and direction inputs. Can anyone tell me
about the Heidenhain encoders? Are they quadrature or are they gray scale
resolvers? If they are quadrature, how many pulses per revolution?
Any light that can be shed on this will be greatly appreciated.
Gerald

Heidenhain encoders are most likely quadrature....
The model number tells the tale. Output type, and resolution.

They used at least three types of outputs. Most common was an 11ua analog output, that was interpolated (multiplied) to get the digital quadrature outputs.
For example with a linear scale, the scale may have 10 micron spacing, but after sending the analog signals through the interpolator box, you can have 1 micron resolution. Same for the rotary encoders.

The also had 5 volt quadrature outputs.

And.... (?) voltage based analog outputs.
Again, they needed an intrpolator box to get digital quadrature output.

The EXE... series of boxes interpolate 11ua anaolg to digital. They usually have switches to set the multiplication ratio.

VERY high quality! Use them if possible.

heidenhain exe | eBay

Thanks for the info, 3t3d. Looks as though I will have to do some disassembly
to try to find some numbers. Then on to research to figure out what I have here.
By chance, is there an internet site that would be suited to identifying 20 year old
parts?
Gerald

The motors are SEM`s and info on them can be downloaded from their website.The encoders are ERO`s and are Ua (microamp) output.These are now obsolete although Heidenhain still has some stock and some resellers also have some too.
The encoder output goes straight to the Heidenhain control without any conversion of the signal.
Why would you want to update the servo drives or do you intend to retrofit the Heidenhain control with Mach or similar?
IMO retrofitting a working Heidenhain control unless with a more modern Heidenhain is a backward step.
I can give you exact part numbers for the encoders in the morning if you wish.

Mark, thanks for the info. You confirmed my suspicions about the motor encoders.
Last night I opened up the housing that holds the XY joystick and manual pulse
generator. The MPG encoder is HR150-05000. id-No. HGB 000 26, Sn-No.
8 403 943 W6. What can you tell me about it? I agree that the Heidenhain is a
very good controller, but I have been using Mach for several years and have hundreds
of routines written. Some up to 60,000 lines of code. Would like to like to be able
to move between machines seamlessly. I needed the rigidity of the Series 2 to be
able to speed up and take deeper cuts. I have tested the drives and all three servos
move nicely and the 151 TNC seems to operate like it is supposed to though I have
not tried it running a test program. If I am successful with the conversion, I may
offer the drives & TNC for sale. I may be making a big mistake but it time will tell.
Thanks again, Gerald

I would suggest going a route like emc2 as that will let you keep closed loop control and also use the linear scales for even more accurate positioning.
The heidenhain converter electronics do 5 fold interpolation of 1µapp signals, which should be good enough to keep some of the position accuracy of the orginal control(if you use that for the scales).
Depending on your gearing it might be enough to simply square up the signals from the encoders and use them as is, for motor feedback and use the scales for positioning.

Also a setup like that would let you keep the orginal servo amps which is way better then converting a fully closed loop system to step-servo.

It's your machine. Do what you want with it.

That said, IMO it's silly to downgrade a working industrial control to a toy control like Mach. EMC, perhaps - at least it's closed loop not "step and pray".