n00b questions on 7i76-5i25

Hey y'all,

I have a 4 axis Taig DSLS 3000 Micromill that I'm currently running off a parallel port with LinuxCNC. I'd like to get one of those Mesa combos, mainly for more IOs to hook up homing switches and perhaps a spindle speed sensor.
What I haven't been able to figure out through reading the docs, is whether I'd be able to set up the second connector on the 5i25 to drive my mill's control box by setting it up with 4 step gens (etc.) on the right pins.

The alternative would be to wire a DB25 connector from the 7i76, which'd be more fiddly and awkward for my getup.

Siggi

Does not compute.
If you have a 7i76 attached to the 5i25 then you have up to 5 stepgens on the 7i76 plus spindle encoder inputs, and more I/O than you can shake a stick at.
The 7i76 manual gives you a lot of information that you don't need to know, but try pages 11 and 12 of the pdf which cover the TB2 and TB3 connectors.
pncconf knows a lot about these cards, so if you run it with the cards installed you can setup a basic configuration right there.
Note - the 7i76 MUST have a source of field power on TB1 or most of the pins won't show up (ask me how I know). A 12v wall-wart will be adequate for configuration, so long as you're not driving the outputs into anything.
Roger
PS - My configuration is 5i25-7i76 plus 7i73 as pendant, and I'm running 4 stepgens (XYZA) on the 7i76.

Thanks Roger,

I realize that I have plenty of stepgens for my purpose that way. It's just that it would be more convenient put a DB25 header on the second connector of the 5i25, set it up to make like a parallel port (but with hardware step gen), and hook up that way.
It looks like there's plenty of hardware in the 5i25 to do this, as it can drive two 7i76 with five step gens each. I just can't figure out how to configure things this way.
Would this be possible by customizing the 5i25 firmware, perhaps?

Siggi

I think he is trying to ask for a way to "plug" right into his machine without doing ANY wiring.

Using just a bear 5i25 should be able to do that, but it may not be the best way. Without knowing more about what exactly is inside your machine's control box, we can't say for sure how good or bad that approach may be.

In the control box there is likely a stepper drive for each axis, and a parallel port breakout board. Between the parallel port BOB and the drives there is likely only a couple of single ended TTL connections. and all other io will also only be TTL.

If the drives are capable of differential connections then removing the original BOB and replacing it with a 7i76 would likely be an improvement, adding differential step/dir signaling, more and better higher voltage io, plus the 7i76's spindle controls and encoder input (also differential). But this route requires you open the box and rewire it.

Why not get one of these and use your 7i76 the way it is meant to be used?

www.ebay.com.au/itm/DB25-Female-Breakout...0:g:nlcAAOSwRUhY8zch

Wire the 7i76 to this and use a DB25 cable to your machine? Personally though, I'd be running separate cables for each motor.

You could use one of the parallel port compatible 5I25 configurations
(choose the one that most closely matches your current pinout)
and change to the 7I76 later.

These are all the current parallel port compatible configurations.
Most of these have corresponding .pin files that show the pinout

5i25_benezanx2D.bit
5i25_bstechx2.bit
5i25_dmmbob1x2.bit
5i25_g540x2.bit
5i25_hdbb2.bit
5i25_mx3660x2.bit
5i25_prob_rfx2.bit
5i25_r990x2.bit

You could make a custom 5I25 configuration that has a 7I76 breakout pinout on one port
and a pinout for a standard parallel port breakout on the other, but note that pncconf is not
going to help you much with configuring that combination

Thanks everyone,

and PCW, thanks for the specific pointers, if you have pointers to docs or links threads on how to modify and build/rebuild the Mesa hardware that'd be awesome.
Also, I've just discovered the "Driver Boards" sub-forum here. It looks like that's likely a better venue for this n00b question in particular, and maybe I'll find examples for what I'm wanting to do there. As a (recovering) software engineer, I think a little bit of code might be a better solution for my needs/wants than a little bit of extra wiring .

Siggi

Todd wrote:

But this route requires you open the box and rewire it.

Yeah, I'm hoping I'd be able to match the existing DB25 pinout and be done with it.

Then I suggest you look through the bit files for the 5i25 parallel port connections that Peter listed. And check to see of any of those will work for you. (my guess is that one or more of them will.)