simpson36,
It is not a simple question of using a port address that Windows does not
normally treat as a printer port. The newer versions of Windows, especially
the 64 bit versions, control ALL access to ports and memory. The only way
to get data to a device is to ask Windows to do it for you. Unfortunately
Windows wants either certified device drivers, or devices that mimic the
standard printer, USB, or Ethernet that consumers use. Note that Windows
will allow you to write to a "printer" but not to the pins of a printer port.
The difference is how it gets done. Windows will deliver all the data, just
not with the timing that you are hoping to achieve. For this reason a
printer port under Windows 64 bit or any USB "printer" device will not
provide reliable timing for the step pulses used for CNC control.
Steve Stallings
www.PMDX.comOn the topic of 'to be or not to be' LPT port, has anyone considered targeting an address configurable LPT card?
Let's say an LPT card costs about 10 bucks. This is not going to impact any rational decision to purchase MACH4. Most new computers don't have LPT ports anyway, so purchasing an add-in card is pretty much a given.
Would it be possible to have MACH4 talk to the UART on an LPT card thru a specific address which is not recognized (and blocked) by the OS. i.e. just use the hardware on an LPT card as an 'interface' between MACH4 and existing LPT based systems. If the OS does not see the UART functioning as an LPT, theoretically it would not interfere. Many moons ago I was trying different LPT cards and several did not register with Windows as LPT ports. They had drivers that emulated the LPT and passed the data stream to the hardware on the card. Absent that driver, the OS pretty much ignored the card.
Alternately, a USB device to simply mimic the simple on/off behavior of the handful of LPT pins would not be complicated or expensive to produce. MACH4 could then just send words to the device to be decoded into the pin array that matches the LPT layout.
There are a lot of ways to skin this cat, but the overall idea would be to have an alternative to a full motion control solution (Kflop, Smoothstepper, etc) at a low cost that would simply mimic an LPT port. If outside the OS, the valid arguments about Microsoft unexpectedly mucking things up would be eliminated.
Just thinking out loud . . .