I have a lathe with a Sargon DRO. I'd like to build a custom interface box to connect to the two scales.
The current DRO display is a Sargon 650 Gold Standard, model 652, 1997. The scales are model XT350. The scales plug into the DRO each with a
25-pin D connector.
Can anyone point me to a good description of what signals and voltages are on the 25-pin connectors to the scales? I assume it may be equivalent to some standard interface, but I found anything that matches.
I guess Sargon went out of business recently. I'm sure I found a manual for the DRO on sargon-dro.com within the last year or so but now they are gone. So far, my web searches haven't led me to any technical descriptions of how the scales talk.
Any help or pointers to information is appreciated.
The only online info that I was able to find last year was the Wayback site, where websites have been archived.
I didn't find the 300 series scales connector pinout there, but you can still find some of the DRO manuals in those archived pages.
The display box provides +5V DC to the scales, the scales output two (A & B) TTL squarewave signals 90 degrees out-of-phase.
The dislpay box circuitry translates the direction, and the amount of travel.
The basic 5V TTL quadrature systems only need four conductors to operate.
You can determine which pin is 5V DC, and Ground with a DMM or voltmeter, and the other two conductors are the A + B signals. Having a breakout box (D-25 to D-25) with test points would be handy to have (to look at signals with the scales connected), but not entirely necessary.
If you've seen other manufacturer's info on how their 5V TTL scales work, that's also how the Sargon scales work. About the only difference is that some TTL scales (and rotary encoders) have a third Z signal for home or zero.
Yes, xray and axolotl, I am very interested in downloading the manual with pictures. I can download the text, but can't figure out how to get the pictures. I tried all ways of turning off the popup blocker and other secuity stuff on Earthlink, but still can't get the pictures. Any suggestions?
Yes, I'm certain that the 300 series scales are 5V DC TTL quadrature, with A & B signals shifted by 90 degrees. These parameters are shown in the 300 series installation guide (near the bottom) at one of the Wayback pages. They just didn't include the connector pinout.
It'll be simple if you've got a dual trace scope.
No need to be concerned about any similarity to the Mitutoyo scale "adapters". They're intended to be used to match older and somewhat newer Mitutoyo products, many of which utilized sinewave differential signals, so the Mitutoyo adapters aren't compatible with your Sargon
There are other manufacturer's websites where more info can be found about scale compatibility issues. Mitutoyo sinewave scales aren't compatible with many other maker's DRO units, same goes for Heidenhain and a couple others.
Newall used to have charts online indicating 5V TTL scales from other makers that would be compatible with their DRO units. Many of the TTL scales are completely compatible with other DRO units, except that the resolution may be different.. finer or coarser. Some of them are designed with a metric layout, some are inch. I believe some DRO units may not be able to properly translate the scale signals if the quartz and reader head (a) aren't matched, and (b) of the same physical metric/inch design that the DRO unit was designed to read/display at certain specific resolutions.
Your 650/300 Sargon components are compatible. I had the same model/scales a couple of years ago.
If you routinely use your scope, you might be interested in looking at rotary encoders for other purposes. The SWI encoders utilize TTL rotary encoders in their TRAK trav-a-dial style DRO encoders, instead of using linear scales. Rotary types can also be implemented for numerous other uses.
Looking at the web pages which you indicated, I think that I see the problem. They have downloaded the original web site and stored it unmodified. This means that the links to images are all pointing into the old place where they used to be, not to any new copies of the images which may or may not be present. A quick check with manually adjusting one URL suggests that they either did not bother to save the images, or they saved them somewhere else.