Re: [CAD_CAM_EDM_DRO] DRO interface circuit

Be aware, the Digimatic spec posted by James is for the 5/10 pin Mitutoyo Digimatic devices only. When you get a Mitutoyo device, the product insert usually gives you the specific pins for the device and basic timing and data format (the dig_summary.jpg is one such example for a caliper). Mitutoyo publishes their Digimatic interface standards for product developers (like us I suppose), and there are various third party tutorials which make it even easier (such as http://www.tinaja.com/glib/muse145.pdf ). Armed with this information one can actually get something accomplished.


The 4 pin cheap imports work completely differently. They do NOT provide any sort of published spec. The only interface option is to find a tool distributor, and have them order it. It comes on the slow boat from China (literally, it seems) and arrives a few months later.

Being the hacker that I am, while I waited for my interface, I tried to reverse engineer the data format, figuring it must be at least similar in concept to the Digimatic. Nope. It is some bizarre two-way synchronous format which I could not replicate or more than partially interpret.

Their black box is 4 pin to RS-232. Kinda interesting. Being the hacker that I am, I had to see what all the fuss (and expense - hundred bucks) was about. Inside the DB25 shell, there is a potted circuit board. After slowly picking off the potting compound, I discovered a fairly complex RTS/DTS powered microcontroller circuit. PIC microcontroller (code protected, naturally), couple dozen discretes, other ICs with no numbers... could not reverse engineer it from here either...


Long story short, I used both in a project, starting with the Chinese and finishing the project with the Mitutoyo due to difficulties in interfacing the Chinese calipers. Between the rock solid Digimatic interface and the absolute scales, it was worth every penny. And in the longrun, there was actually a cost and size savings, as I did not require their little black box.


Probably more information than you wanted to know about... :)

Steve Devine

----- Original Message -----
From: "Larry Goldberg" <l_j_goldberg@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, October 14, 2002 12:10 PM
Subject: [CAD_CAM_EDM_DRO] DRO interface circuit


> I thought I had seen a schematic and logic diagram of the four pin
> interface used in Mitutoyo calipers, scales, and Chinese copies. A
> search of the archives was unsuccessful.
>
> Has anyone interfaced directly to these devices, and used them for
> closed loop control? Could you post the information or a link to it?
>
> Thanks,
>
> Larry
>
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