Another "what do I need" thread. Vmc retrofit

thewho wrote:

Is there any disadvantages to use revolvers other than it's hard new if one breaks.

No, and there are some advantages as they are absolute so even if you get a bad position reading due to an electrical glitch it recovers next time sample.

I run my milling machine with resolvers and a Mesa 7i49 board and I have decided that any future machines (I plan another lathe conversion) will use resolvers too. I prefer them to encoders.

There are lots of resolvers on eBay, and some are even reasonably priced, if you are concerned about spares.
www.ebay.co.uk/itm/131370539881

I would suggest the 5i24 + 7i49 (for which there is a compatible firmware) to control the drives and run the resolvers and then something like the 7i37TA to connect the other IO.

If you need a lot of IO then the 5i24 / resolver firmwares seem to all have smart-serial modules, so you can hang (in theory) up to 8 smart-serial cards with up to 384 IO pins on the third connector.

thewho wrote:

The 5i24 16 or 25?

The 5i24_16_rmsvss6_8.bit firmware seems to be available for both versions. With the 7i43 it normally pays to get the "bigger" one as not all firmwares fit on the small one. Similarly with 5i20 v 5i23. I would take advice from Mesa on the subject, but I suspect that both versions have much "bigger" FPGAs than the 7i43.

So 5i24, 7i77 and 7i49 would be a good route to take?

The 7i77 is part of a different "family" of cards to the 7i49. The Mesa cards are divided into the DB25 family and the 50-pin header family. The 7i49 is a 50-pin card, and the 7i77 is a DB25 card and won't physically connect.
However, the 7i77 is probably of limited use to you anyway, it would add encoder counters and +/- 10V analogue outputs, but you don't need encoder counters and the 7i49 has analogue outputs.

(If you _do_ need encoders then the firmware I mentioned above supports encoders on the middle connector, but connected via 7i33TA (typically) rather than 7i77.)

Is there differences between resolvers? I have Heidenhain 4xx something revolvers.

Are you sure those are Resolvers? A quick Google suggests that Heidenhain only do Encoders, and 400 series are encoders: www.heidenhain.de/de_EN/php/documentatio...034/file.pdf#page=32

I think this needs to be clarified before continuing.

thewho wrote:

]And that is apparently a "Incremental Sinusoidal Encoder" I did not find a datasheet for that specific one but it should be 250 lines/rev.
Witch make me think they are a "no go" for this application?

"Sinusoidal" encoders output a sine wave rather than a digital square wave, so the hardware can measure level to interpolate to far more than 250 lines per rev accuracy.

Bear in mind that the machine used to work, so the hardware must be adequate.

I think what you will need is an "EXE" box:
www.ebay.co.uk/itm/Heidenhain-EXE-610-C-...&hash=item5413be0b38

Or similar. Different models have different interpolation ratios.

It is entirely possible that you already have a set, or the equivalent might be part of the original control.

thewho wrote:

And I don't like the idea of buying old Heidenhain converters when I can buy new for less.

The EXE units are still current.
www.heidenhain.com/en_US/products-and-ap...nics/exe-100-series/

They are an integral part of the sinusoidal encoder chain. Mesa cards (and Pico, and partport, and the others) can use the output of the EXE. They also rather usefully allow you to choose the resolution / count frequency tradeoff to suit your application.