thomas, there is no advantages to use 2 limit switches i think. mach2 don't
use the limit + or limit - information separatly. The only thing a limit do
is Estop mach2, and eventually homing for combined home limit switch
strategy (i don't like it). It's better to use a mechanical ramp who will
trig the limit switch at the end of each axis limit, and to keep your money
for a second switche by axis for referencing. Like this you will get
software limits working, and you can have your ramps limit switch set just
after this software limits, with hardware power off on them in case your
servos or mach2 become made and run away.
if you have 1 reference switch by axis, you can reference all your axis at
the same time, and you can connect in serial all your limit switches to take
only 1 mach2 input. This make a total of 4 input for 3 axis. It's the better
setup, not expensive (2 switches per axis, 1 dual ramp for limits and 1 half
lenght ramp for reference by axis), save mach2 inputs, and give you a true
referencing possibility with setable software limits. this give you too the
possibility to put the reference switch in the middle of each axis, this is
really a time keeper strategy, because you will not need to go at 0 machine
position to reference.
This is well explained in the John's manual, but this strategy is not often
choosed by beginners certainly because when they see their machine joging
with mach2, they forget they could keep a lot of time with a true separate
referencing, software limits, and hardware limit switches for urgency power
off.
Olivier.
