Interface Questions?

[widgitmaster]

What is the difference between a "Breakout Board" and a "Parallel Port Interface"
Why is a breakout board called a breakout board, is it made to be broken?

Which one will work best with Gecko's G202's?

The Non-Electrical Widgit

[Eurisko]

Widgit,

A breakout board is user-configurable. There are breakout boards available for a variety of different interfaces (parallel, RS232, etc.)

It allows the user to reconfigure the wiring on a standard interface, usually by jumpering wires to different locations for custom hookups.

Say you want a DB25 connector with only 3 lines active. You can jumper the wires inside the breakout board and keep only the signals that you need, at the pin locations that you want.

[widgitmaster]

Ok, I remember in my beginning computer days there was a "Breakout Box" that would allow you to reconfigure an RS-232's wires for various reasons. So "Breakout" refers to the ability to sever the line and re attack at a different point or pin.

So If an LPT interface can communicate signals from the stepper controllers and limit switches on pre-defined pins, why is it still called a Breakout board and not an interface?

The reason I'm asking, is because I'm going to build a complete router with all the electronics, and I have little or no experience in electronics! Some of these terms are ambiguous and confusing!

Widgit

[Eurisko]

Widgit,

The terms do seem to be misused.

The important thing is that you find a solution that will make your wiring neat, short, and efficient. I tried to post a photo of a typical breakout board, but Photobucket isn't cooperating tonight. Mine simply "breaks out" the DB25's pins to screw terminal blocks on the board.

Do a Google search and compare some of the features of the different boards.

Fare well, Widgit. Always a pleasure to read your posts.

[BobWarfield]

Eurisko is correct. Technically, that little board in the top left of my chassis is a breakout board:

http://www.cnccookbook.com/img/Lathe...s/P4213943.JPG

All it does is connect the terminals on the DB-25 to screw terminals. It makes it easy to wire up point to point.

Some people use these and connect right up to Gecko Drives because they're cheap. The trouble is, you will fry your PC if anything goes wrong, or if you do anything wrong, and you will reduce the noise immunity too.

Hence the parallel boards like outfits like Campbell sell. These are simple too. They isolate with an "optoisolator". That's a funky chip that converts the signal to light passes the connection between the two sides as light and then converts back to electricity. That way, nothing but the information of whether the signal is on or off can pass between the two and they're isolated.

I prefer to use a parallel interface just because of the protection they provide. It adds some cost and they are (usually) not as compact.

Check out the Xylotex products. That's what I used on your minirouter I bought. Everything is on one handy little board including a parallel interface and even the step motor drivers. No Geckos required. It's main limitation is it won't drive the larger step motors. But it'll run a 425 oz motor, which is pretty stout for these little routers.

Cheers,

BW

[Eurisko]

Originally Posted by BobWarfield All it does is connect the terminals on the DB-25 to screw terminals. It makes it easy to wire up point to point. Some people use these and connect right up to Gecko Drives because they're cheap. The trouble is, you will fry your PC if anything goes wrong, or if you do anything wrong, and you will reduce the noise immunity too.

Bob, I'm a little confused.

The Gecko G202's step and direction lines are already isolated. Are you advocating doubling up on the optoisolators?

[BobWarfield]

Originally Posted by Eurisko Bob, I'm a little confused. The Gecko G202's step and direction lines are already isolated. Are you advocating doubling up on the optoisolators?

Yes! Why? Because I'm not worried about protecting the Geckos, I'm worried about protecting the mobo on your PC. There's a bunch of wiring in a typical box. You're not just running step/dir to the Geckos. You've often got a DC power supply (try letting 80V onto you PC mobo, yikes!), home/limit switch wiring, relays controlling spindle and coolant, yada, yada:

http://www.cnccookbook.com/img/Lathe...s/P4213943.JPG

That's my chassis using a Grex as the equivalent of the parallel interface. Quite a few wires there and I'm not done yet. The non-isolated breakout is a connector to my lathe control panel, not my PC.

Can I guarantee I'll never get a wire crossed while I'm fooling around inside there? Will a wire never come loose and accidentally short on something with all the vibration near a CNC?

Nah, I can't promise that. In fact I already crossed a couple wires and got weird behaviour from a stepper while wiring it up.

If I cross the wrong wires with a pure breakout board, I fried my PC mobo. I'm hating life. If I cross wires with a parallel interface, I fried the optoisolator chip on that card. It's a cheap mistake to fix.

It's just insurance. If you don't want to buy the insurance, don't buy it. If you wire everything up right, it oughta work.

Cheers,

BW

[Eurisko]

Thanks for the quick reply, Bob.

I will definitely use some optos to protect my mobo. Unfortunately, the only ones I have on hand are some 4N35's. With 10 usec switching , would probably be useful only for the limit switches and peripherals.

Now I need to find a nice control box. Any ideas?

Widgit, are you still with us?

[BobWarfield]

Search eBay for "NEMA". Looks for enclosures in what comes up. NEMA boxes will have weather sealing so they're a good bet. Look carefully at dimensions--they can seem real big when they arrive!

If you prefer rack mount, they're available on eBay too. I used a couple. They can seem tight though.

Cheers,

BW

[widgitmaster]

Originally Posted by Eurisko Now I need to find a nice control box. Any ideas? Widgit, are you still with us?

Check this guy out on eBay, he has a large selection!
If it's not on his eBay, send him an email and he will have it for you!
http://search.ebay.com/_W0QQfgtpZ1QQ...3aMEWNQ3aMESOI
Eric

[ger21]

Originally Posted by BobWarfield If I cross the wrong wires with a pure breakout board, I fried my PC mobo. I'm hating life. If I cross wires with a parallel interface, I fried the optoisolator chip on that card. It's a cheap mistake to fix.

You can buy PC motherboards for a lot less than some breakout boards. Now if you fry more than just the motherboard, than that's a different story.