Hi,
use Mach to generate two or more numbers, each one representing the speed of a spindle.
Those numbers are transmitted to a PLC which turns those numbers into analogue voltages, one
for each spindle. Thus you could have a number of spindles up to the number of independent
analogue outputs of your chosen PLC.
There are PLCs which can generate step/direction signals. Whether any (affordable) PLC has more than one
step/direction output pair, and whether they can be synchronized is more than I can say.
For example, if I require a 1500 rpm CW (M3 S1500), how would this code be translated for the PLC.
In short, you can't transmit that to a PLC. The S word is the speed of the ONE spindle defined in Mach and it does
not need to be transmitted anywhere. The primary spindle 'consumes' this signal.
The speed of secondary or tertiary spindles would have to be set by defining numbers which are subsequently
converted to either analogue outputs OR step/direction signal pairs, should your PLC be capable of that.
Quite frankly you are pushing, or trying to push, Mach3 beyond its intended capabilities. You might get a result
but I think it will be long, difficult and error prone. I wish you luck.
You could use out-of-band axes as provided by Mach4. They can be made to be free running with a little cleverness.
They are not coordinated axes however.
Mach3 and Mach4 are limited to six coordinated axes. Thus if you have five axes for motion that allows one
coordinated axis leftover. That axis could be a rotationally synchronized spindle. Further spindles could NOT
be synchronized in the same fashion because there are no further coordinated axes left.
You can have positionally accurate out-of-band axes in Mach4, we would call them 'indexable axes' but not coordinated.
For example if you commanded a two positional jogs for two out of band spindles, say one to rotate 3600 degrees, ie 10
revolutions at a speed of 360 degree/sec and the other 7200 degrees or 20 revolutions at 720 degree/sec they should
arrive at their respective destinations at the same time. What could not be guaranteed however is that they will maintain
perfect 2:1 positional accuracy throughout the move, even though they would end up in perfect 2:1 at the end of the move.
Craig