DRO suggestions (computer input like via USB)

I can't see any reason you'd want compute output from a DRO. Good DROs will guide you through bolt circles and other such stuff and if you need something fancier than that you need full CNC. In other words, if there was a need for it, it would already exist.

Pete C.

Pete, yes, I understand what you are saying, though I think that it does have value. Anyway, Newall C80 does seem to offer this capability, though it is pricey.

I will hold off buying a DRO for some time to learn a little more.

i

Are you making a Coordinate Measuring Machine, Iggy?

--Winston

The Newall C-80 is an excellent unit that has this capability, via serial port. The data is in a very easy to use format, I don't remember off the top of my head, but I think it was just in the form of axis + value for all 3 axes. I believe it is actually fast enough to use as a closed-loop encoder for a cnc system. In one of my previous posts I described a number of the advantages of the Newall system, so I won't reiterate those unless you want me to ww88

Mitutoyo KA series has RS232 option. The one I bought for my lathe came with scales good for .00005 thousands of an inch (over kill for a mill, but great for the lathe cross feed). I got it from Penn tool on sale. Had to pay slightly more for the scale outside the package. I don't recall what the 232 kit cost.

Only problem is RS232 is obsolete, I don't know if newest version of windows supports this bus.

Ignator

Yes, the C-80 system looks very nice indeed. Pricey, but very nice. The output seems simple enough to read from a Linux laptop.

i

RS232 is not obsolete be any means. While crappy consumer PCs may be dropping it, the rest of the computing world still supports it just fine.

What!? Centronics is. But RS232 will stay forever.

Nick

On Tue, 12 Jun 2007 11:44:46 GMT, with neither quill nor qualm, "Pete C." quickly quoth:

So a 4MHz 8086 computer with an RS232 is just fine with you, eh? I'll stick with my 2GHz Athlon and USB2 ports, thanks.

- Metaphors Be With You -

I use a computer daily, for work, with a clock speed measured in kilohertz. It's simple, reliable, and does the job. There are two main reason most people seem to need faster machines - chrome and bloat.

On Tue, 12 Jun 2007 13:55:31 GMT, with neither quill nor qualm, _ quickly quoth:

No dispute, but there is a third reason.

-- Instant Gratification Takes Too Long! -------------------------------------

I think that most computerss still have RS232 ports, and there are also RS232 to USB adapters sold for not too much.

i

I am in the market for a cheap DRO setup for a minimill and/or a mill-drill. Ideally I'd like to use the cheap chinese scales, output to an old 486 notebook computer I can't bear to throw away. It would make a good display for the coordinates. So I'd need some sort of interface cables from the scales units to RS232. That would let me use the laptop on both mills. Anything like that out there?

I second this question.

i

Maybe if you choose scales that output TTL quadrature you could interface these to the parallel port and use EMC2 and one of its front ends to interpret and display the results. I chose Newall for my lathe DRO for this reason, I can tap into the quadrature and feed it elsewhere other than just the display, now if only I could get a roundtuit.

Still

Nick

What I said was slightly incorrect, the Newall scales I have output differential quadrature at RS422 levels and so a RS422 to TTL converter chip would be required but the chip for that is common enough. I would then expect you could input the resulting TTL directly to the parallel port but some form of buffering or isolation might be a good idea.

I can't remember how many input lines the parallel port has configured as input normally for printer use but under low level software control I think the outputs can be configured as input if required due to the PIO chip.

Worth having a look at the EMC2 live demo as that has a number of preprepared examples which should give info about hookup, it would seem that at least 2 quadrature encoders can be hooked up at the same time. The demo has links in some of the documentation for the examples. Someone did a CNC etch-a-sketch.

They used to be a file on the Newall site that gave encoder compatibility, the file gave the maker and output format of their scales and what Newall reader units were compatible. The last time I looked the file was not longer there and they had altered the website, maybe a request for the data would get it sent to you. You may therefore be able to get TTL quadrature output scales, maybe other scale makers give this info.

David, since I use Linux, this is of particular interest to me. I am assuming that you are referring to EMC2 mentioned at

Please forgive me if my question is wrong or stupid. Is that true that "scales that output TTL quadrature" could be directly connected to the parallel port?

Or do I need some sort of a multiplexer to take inputs from several (say 3) scales and outputs one stream of signals to the parallel port?

I am browsing that website and would say that it would be quite close to what I want if I can get the scales to send their positioning data into my computer.

i

Did you actually try that, or do you suspect that? A PC that is challenged by his non-RT-OS will lose steps every once and a while.

There is a reason that neither Mach3 nor EMC2 use QE-signals (or any) as feedback.

Nick