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General Mach Discussion / Parallel port clock signal to run a latch - is it possible with Mach3

« on: February 04, 2007, 12:58:52 PM »

I have an old CNC machine that I am trying to update with Mach 3 software.  I am trying to do it with the least amount of changes to the machine.  The machine already uses a parallel port for communication with the computer.  The parallel port signal comming into the machine goes through a latch.  The latch control is connected to pin 1 of the parallel port - the clock signal.  So for the latch to work (transfer what appears on its input pins to its output pins)  it needs a clock every time any signal coming from the computer changes.  I put a 'scope on the step and direction signals and they look good but the clock line just has a little bit of noise on it.
Questions,
Is the parallel port bad - that is, does Mach 3 normally send a clock signal on line 1?
If Mach 3 does not normally send a clock signal on line 1 can it be made to produce one?
Is it better to scrap the old interface board, buy one of the many ones that are sold and connect it directly to the existing step and direction connections?

Thanks