[kreutz]

As suggested by Harryn, here is a new thread for this subject.

The idea is to use a hardware splitter to allow the use of up to 6 motor pairs on dual drive axes with Mach3.

Mach3 allows to slave two motors on one axis by software, but is restriced to 6 axes total, so using that feature would eliminate using independent 4th and /or 5th axis if X, Y and Z are dual motor driven (or if you want to use multi spindle heads driven simultaneously and already have X and Y with dual motors each). At the same time you are restricted from using the rest of the LPT input output signals for spindle, vacuum, cooling pumps, charge-pump, etc, since they are being used for axis drive signals.

The solution is a hardware splitter interface, so you could use up to 6 dual drive axes, or any combination of dual drive and independent single drives to a total of 6 (Mach3 limit).

Here are the Schematics for such a simple interface. As designed, you can use dual drive on X, Y and Z axes, axis "A" is independent and driven only on the Master interface. Any (or all) of the Slaves could be left vacant. More single axes could require a second Lpt port if you use all the extra outputs in LPT1 for control (vacuum, spindle, charge pump, enable, etc)

In order to use more dual motor axes (more than 3), it could be necessary to use a second LPT port and another splitter board, if it is only 1 more pair, you could add an extra 74HCT14 chip and connect the other pair ("A" axis), Step and Dir signals on pins 8 and 9 of the LPT port, to two of the added 74HCT14's gate inputs, gate outputs go, through the extra inputs of the 74HC240 inverting buffers, and respective buffer outputs, to both (Master and Slave) interface connectors (pins 8 and 9 respectively). Similar to the rest of the axes' connections. Don't forget to tie the rest of the (non-used) inputs of the added 74HCT14 to ground or VCC.

Used Step and Direction pins on the LPT port are assumed to be pin: 2, 3, 4, 5, 6, 7, 8, and 9 (for the 4 axes), being pin 8 and 9 used for the "A" axis.

Enjoy!