The SS isn't a breakout board, it is the replacement of 2 parallel ports that can pulse much faster than parallel ports. You may still want to use a breakout board for opto isolation. You could use the SS plus a mod device or the G100 with the IO only plug-in. The g100 would be able to handel a good bit of additional I/O. Probably enough for for a pretty simple tool changer and if you can't find a G100 cheap, I'll sell you one. I wouldn't use the G100 for motion control but if it can handel all of the extra I/O you need, may be a cheap alternative to a PLC.. The SS is far superior to it as far as motion control. The disadvantge of haveing the SS control the tool axis is you will loose time on tool changes.

Hope this helps a little.
Brett

I'm not made of money but I don't mind spending it if needed.

So what would be the simplest way to index the changer using a stepper.
Remember I have a running machine that has the current BB full.

I would like this to be an add-on.

Ok you need to be specific tell use what your I/O requirements will be, the type of ATC i.e. standard rotary, hot swap, hot swap-swap arm. The standard rotary is the cheapest to do. What is the Sequence of events for the ATC? What type of error checking Proxes to varify things have moved, not in the way, etc........

Once you know Your I/O that does your movements, and error checking, sequence of events, Electromotion type i.e. steppers/servos, how many?

Also, if speed is NOT an issue, then standard rotary is fine, and you can use one of your unused axis.

if ATC change time is a REAL issue then you will need to move everything off board onto a PLC.

I use Air cyclinders/solinoids for my ATC arm, (and swap arm) motion, and 1 or 2 servos depending on type of ATC.  You can get STUPID fancey with this stuff, but as the complexity rises, so does your cost, headaches, cussing, hair pulling, and DEBUG Time!!!!!!!  I use the CTRIO modules from ADC to run my accessory servos independant of mach, but, I will tell you that those modules are a pain in the butt to learn, they are POORLY documented on how to use them for pulse train sources.

scott

This it is how the changer will work.

The changer will have 3 axis.

1: The Z will go to a preset and mach
will send a signal to start the change.

2: The TC will slide on a rail and engage the tool.
It will leave a switch to let the PLC know that it is not there and when it engages the tool contact a switch
letting the PLC know where it is.

3: It will activate the draw bar, the bare will leave a switch and contact and switch to let the PLC know
where it is.

4: The TC will then drop down leaving a switch and
contacting and switch to let PLC know where it is and send Mach a signal to index the changer “x # of deg’s”Mach sends a signal back to the PLC to reverses the proseager and tells Mach when it has returned home. 

5: The PLC tells Mach the coast is clear and cycle start.     

That could all be done in VB and with probably a parallel port (depends on amount of I/O)  or you could also use a PoKeys to get the I/O required.
 Personally I would use a PLC to do the linear movements (slides with air or hydraulic) and monitor the switches etc then use an axis to do the rotating. VB would be less than the first as most of the routine would be handled by the PLC.
 Scotts way of controlling things totally from PLC is good but as he said it starts to get expensive when controlling motors accurately from a PLC.
In the future I am planning making a toolchanger for the mill I am working on, I have a servo drive/motor which will be used for the rotation. The drive I have has indexing (64 positions possible I think) so it it will handle the rotaion and it also handles which direction to go for shortest rotation to the next tool so matters are even more simplified for me

Hood

What are PoKeys?

http://po.labs.googlepages.com/pokeys
 Art hasnt got the analogue inputs/output done in the plugin but the digital I/O seems to work fine in the testing I have done, see here as well http://www.machsupport.com/forum/index.php/topic,6920.msg48987.html#msg48987


Hood

I would like for Mach to keep up with the TC indexing on it's own DRO.
That's why I ask if Mach could run another axis outside of the printer port.

If the PLC controlled the axis how would Mach know where it was?

Not sure really what you are asking but will try and answer.
 Your Gcode says to get another tool, you have a M6start.m1s macro which you put your VB code into, this tells whatever hardware you have to do its thing, once it is done and the new tool is in position it sends a signal to Mach to say the toolchange is complete and Mach continues with the code.
 As an example my lathe sends a signal to the PLC over Modbus, the PLC then starts its toolchange routine and continues with this routine until the correct tool is in position, the PLC then sends a signal to Mach to say its at tool * and Mach then carries on. There is no need for Mach to know where the changer is at any other point in the routine as all it cares about is the tool in position signal so that it can get on with its machining

Hood

I can see how that works.  It makes sense. 

If you are using a stepper, how do you zero tool #1?  If it were in a DRO in MACH, I could see how you could zero on your first tool and then every tool after that would be X amount of degrees.