Posted this on the "zone" but might get more help here   

Been running Mach3 on my laptop via a buffered, not optoisolated, BOB.

Quite successfull, no problems.

Now as per prevailing opinion I have hooked up a desktop with on board LPT. 1.67 ghz 368 mb

Same version of Mach, same xml, same printer cable. Ports and Pins still correct.

But it is just not getting any signal from my homing and limit switches. Even the estop does nothing.

Doesn't matter if active low or high. Motors run fine on jog so its not port assignment issue.

Swap back to the laptop and no problems.  Do I have a dud mother board? Something I'm overlooking?

Any clues???

Possibly a 3.3 volt system? The older stuff is better as it's all 5 volt, possibly need a scope to check it.

I think the 3.3V would effect the outputs more than the switch inputs. the motor signals are working which shows enough is being output to drive the controller.
can you see any switch activity on the diagnosis screen?

No response on the diagnostics screen at all. Either active low or high.

Being a buffered BOB I would have thought it would cope with 3.3v signal anyhow. (not an expert, just a carpenter)

Limits and homes are photo interupters. So possibly 3.3v is not enough for the LED side of them.

Funny how even the estop does not work.  NC switch.

In effect outputs are OK, inputs are not.

Have a look in the Bios and see what type of LPT out put is set, check its the same as on your laptop.

Graham.

Thankyou people for your responses to my query.

I was ignorant of the different LPT modes so did some googling and learned a bit   

Laptop was ECP and desktop that worked was ECP too.

Tried all the options given in Bios and still no different.  NORMAL, EPP, ECP- DMA3,  EPP+ECP

Looks as if I have a sus mother board.

Bring on the ncPOD  I say !!!!!!!    

Whay not get a 5V pci card ?
Siig makes em' as well as a few others .

Yodawill2000  I see the perfect logic in what you sugest, however this was more a curiosity question for me rather than a dire need.

My laptop is what I have been using up till now and is my preffered machine.

It has been 99% fine.  Not 100% because it just struggles a bit to provide a completely clean pulse stream.

Hence my enthusiasm to see the ncPOD come on the scene.

I tried the desktop because I see so many posts saying you should not be useing a laptop, (mostly on CNCzone) so thought I would give it a go.

It is still not my preference but I may have to if the ncPOD does not proceed as I am hoping it will.

Gotcha'
Now a question ,, hehe  What the heck is a ncPOD ??

Gotcha'
Now a question ,, hehe  What the heck is a ncPOD ??

See the thread called "Mach to DeskCNC?"