[GTFreeFlyer]

Can I use the A-Axis pins on the DB25 Parallel cable as inputs instead of outputs? I am running 3 axes and I need to attach my probe somewhere and Input #4 on my G540 is taken. Mach 3 is loaded on my PC built into the machine and since I don't have it running right now I can't check it.

Much thanks in advance!

[doorknob]

I don't know for sure, but IIRC the step and direction outputs for each axis are optoisolated from the PC to the G540, while the input pins are optoisolated in the other direction from the G540 to the PC, which means that you would likely have to do the equivalent of open-heart surgery on the driver in order to repurpose one of those pins as an input.

But I believe that you can open the G540 housing (if you're careful) which should give you access and permit you to remove one of the four drivers from its carrier, and so maybe you could access the broken-out pins of the DB25 connector for the removed driver and make do with that.

I have seen photos of disassembled G540s, but have not taken mine apart, so I do not have direct experience doing that.

[GTFreeFlyer]

I was planning on actually cutting one of the wire strands inside the parallel cable that goes to the G540's A-axis, and then tapping into that wire with the probe's wire so the connection continues to the PC. From the G540, the signal would just reach a dead-end where I cut the wire. Thoughts? I'm just wondering if I can set that specific pin from an output to an input in Mach 3. Thanks.

[doorknob]

From the G540 manual, A-axis step is DB25 pin 8 and A-axis dir is DB25 pin 9.

A quick look at the documentation for the CNC4PC C10 breakout board shows that pins 8 and 9 may be used either as input or output pins, which leads me to believe that that is a capability of the parallel port itself.

So IMHO since the hardware apparently supports either of those pins as inputs, Mach3 should also support that, however I do not currently have a version of Mach3 to test it on.

[Mzones]

NO!
There are 5 inputs an a parallel port.
Mach can only receive input signals from pins 10-11-12-13-and 15.
These are the only pins supported by the printer ports' hardware , driver
and mach 3 software.
Pin 15 is being used by the G540r to send fault signal.
That means that there four inputs left.
What and how do you have hooked up to each of these inputs #1 #2 #3 #4 ?
I am assuming that you are wanting to hookup the following.

1- Limit switches
2- Home switches
3 - E stop
4 touch probe

The home and limit switches can share the same input, or the
home and the probe can share the same input.
This would leave 1 extra input

When all else fails Read the Mach 3 users manual.

[doorknob]

I stand corrected - I should have probed a bit deeper rather than drawing conclusions from the native C10 capabilities.

[john-100]

Hi

the PC printer port can provide 5 inputs and 12 outputs or 13 inputs and 4 outputs

pins 2 to 9 can only be set as 8 inputs or 8 outputs you can't mix and match and program them as say 6 outputs and 2 inputs

during the last few weeks I've been looking into the PC printer port circuit and IEEE 1284 termination network
to come up with my own breakout board

I've not yet decided if I will use the 74LS541 with octal buffer with schmitt inputs or 74LS245 bi directional octal buffer -
makes it easier to switch the direction of the data into or out of pins 2 to 9

Attachment 214528

John

[Mzones]

Lets change the question. Forget about "Can I use the A-Axis pins on the DB25 Parallel cable as inputs instead of outputs? "
I still say NO.

Lets work with a question more like this.

How can I make this work, with the available output pins that I have available?

You do need to post everything that you want to hook up.

[GTFreeFlyer]

Thanks guys. I had inputs planned as follows:

1. X limits and home
2. Y limits and home
3. Z limits and home
4. E-Stop
5. Tachometer for seeing the RPM on the Mach 3 screen
6. Touch probe.

I've simply just removed the tach and am using the touch probe instead. I can see the RPM on my SuperPID LCD anyway. No need to have it in two places, although it seemed like a neat idea.

[doorknob]

Time for a second parallel port (add-on card)?

[Mzones]

GTFreeFlyer

Consider one of these as a option

1. X Y Z limits
2. X Y Z home
3. Touch probe.
4. Tachometer for seeing the RPM on the Mach 3 screen
5. E-Stop

Or this.

1. X Y Z limits
2. X Y Z home and Touch probe.
3. Tachometer for seeing the RPM on the Mach 3 screen
4. E-Stop


The probe can use the same input as the homing switch,
because home limit is only active while homing and the probe is
only active during probing moves.
Hope that this helps you.


Mike