SPC/SPI serial communication with DRO's

[Doug Fortune <pentam-at-home.com>]

Keith Rumley wrote:

>
> For the past couple of months I've been proceeding to convert a Bridgeport
> (Moog Hydrapoint, actually) to EMC. (August 2000, I think) RTLinux 2.3
> /Servo-To-Go II, with Emerson FX/DX490 servo drive and motor pairs.
>
> I'd like to make use of the Mitutoyo ADS2 absolute scales on the mill to
> read positioning data into EMC. The scales use a capacitive read-head unit,
> which communicates with the DRO serially. My thought is to poll the
> read-head using its serial protocol, and read that data into EMC's
> positioning feedback loop.
>
>      From talking to a tech person at Mitutoyo, the serial data wouldn't be
> blazingly fast, but the DRO unit is supposed to keep accuracy up to one
> meter per second. Another little quirk - he faxed me some schematics,
> pinouts, and protocol info, but the clock rate for the data spacing was on a
> page not faxed. (It was a long time getting this much info...)
>
> Does the PC seria! l port have enough speed for this, and how would it need to
> be meshed into EMC?

Welcome Keith:

I posted this January 19, 2001 on CAD/CAM/DRO:

> Does anyone know the electrical pinouts for the
> Mitutoyo DRO/scale interface ?

While researching the above, I came across a web page
(with circuit diagrams and source code) that covers
converting a Starrett 737 Vertical LCD Scale  mounted on the
quill of a JET JT830 vertical milling machine, to a large
Mitutoyo LCD Display readout:

http://www.matronics.com/cncscale/index.htm
Web pages courtesy of : Matt Dralle  dralle-at-matronics.com

Apparently, the SPC protocols of the two devices are incompatable
and therefore need translating, which Matt has done with a circuit.

Hope this helps you out.

Doug Fortune
http://www.cncKITS.com