Interfacing the scales of a Tesa 3d micro-ms 545 CMM

I came across a Tesa 3d Micro-ms 545 CMM unit, but without the computer and the linear scale interfaces. (And no documentation)

It has a Renishaw PIM probe and it’s PI2-6 interface unit.

Anybody got experience with this CMM, do the three axis connectors go through interface units before connecting to the PC, or are they connected directly to the pc?

Is the pc interface a special Tesa card, or is it a Renishaw product? (I am guessing that the glass scales is Renishaw products, but they have no markings what so ever.)

The connectors are male 15pol dsubs, with 11 pins populated. And internally the read heads has 10 pins connected by flexfilm from the optical assembly.

Do anybody know anything about these interfaces? Is there separate interfaces available for these the linear scales? (They are open glass scales, reflective solution, with only the LED’s and photo-elements onboard. The rest of the electronics seams to be placed int the missing interface units.)

I was hoping to be able to get things up and running as a simple relative measurement platform.

Any help is much appreciated.

malman said:

I came across a Tesa 3d Micro-ms 545 CMM unit, but without the computer and the linear scale interfaces. (And no documentation)

It has a Renishaw PIM probe and it’s PI2-6 interface unit.

Anybody got experience with this CMM, do the three axis connectors go through interface units before connecting to the PC, or are they connected directly to the pc?

Is the pc interface a special Tesa card, or is it a Renishaw product? (I am guessing that the glass scales is Renishaw products, but they have no markings what so ever.)

The connectors are male 15pol dsubs, with 11 pins populated. And internally the read heads has 10 pins connected by flexfilm from the optical assembly.

Do anybody know anything about these interfaces? Is there separate interfaces available for these the linear scales? (They are open glass scales, reflective solution, with only the LED’s and photo-elements onboard. The rest of the electronics seams to be placed int the missing interface units.)

I was hoping to be able to get things up and running as a simple relative measurement platform.

Any help is much appreciated.

Click to expand...

If you are missing the computer and have nothing but the probe interface and the scales, then I recommend you contact Deva ( Deva Electronics - Home ) and enquire about one of their CMM kits.

Thanks gregormarwick

That lead me to some new insights..

As this is a low budget project, and I am an electrical engineer, this is handeled as a side project where i intend to build the electronics and software myself. I am not aiming at a full blown high precision CMM, but a more modest measurement tool.

But Devo had a product Devo023 Reader Head Pre Amp for Brown & Sharpe, that seams to fit my scales.
I also came by the info that the scales is made by B&S.
And found some B&S ones on ebay, so it is confirmed in my book.

My next step is to try to find out how these passive read heads shall be driven electronically.. ie LED current, and drive circutry for the photoelements, (phot-diodes or -transistors) there are four of each representing 0,90,180 and 270 degrees of a transition between two gratings on the glass surface.

Combining these will give me the normal analouge sin/cosin interface. i just have to find out how the four signals is used to cancel out amplitude and offset errors.... then it shall be fed into the interpolator to give me the RS422 encoder signals... one step at the time... first led and photoelement interface....

Anybody got info about these read head interfaces?

New try... my first attempt seams to have gone into cyberspace....

First, Thanks gregormarwick

Your tips gave me some new valuable insights.


I'm an electrical engineer, and as this is a low budget hobby project, I intend to do the electronics and software myself.
My goal is not to get a full blown high precision CMM, but more to get a basic coordinate measurement platform that can be adapted to my needs.

Following the direction to Devo website I found their product Deva 023 Reader Head Pre Amp for Brown & Sharpe which seam to fit my scales. And got this confirmed by their sales. I also got the info that the scales (and possible the whole unit) is build by B&S. Following this info i found Read Heads on Ebay which matches my heads.
Through the datasheet for the deva 023 i got the pinout which match my connectors, and by that some info about the read heads. Which have four LED's and four photoelements (photo-diodes or -transistors) each representing: 0,90,180 and 270 degrees transition between two gratings on the glass surface.

These four signals is then to be combined to generate the analog Sin/Cos output signals. These can then be fed into a interpolator which can determine small changes in the signals and then generate the A/B quadrature output common to scale interfaces.

My next step is to figure out the drive electronics for the read heads, ie LED current, Photo element drive circuitry and so on.

If anybody got any tips or information about this I am eager to hear.

(I also realized that my hobby diagnosed number dyslexia got into play.... its a 454 unit, not a 545)