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George,

On our breakout board we use pin 10 for the ESTOP.

Bob Campbell
Bob@...
www.campbelldesigns.com
Breakout board
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Stepper Motors

How can I interface an ESTOP external switch to mach2. I have the
PMDX.com parallel interface board and it does not seem to have an
estop connection? Can I specify in mach2 which parallel port pins
will be the estop (such as in the case of using a 2nd parallel port)?

Thanks,

George:

Yes, specify the EStop pin as whatever you wish...

Art
www.artofcnc.ca

--- In mach1mach2cnc@..., "george_barr"
<george_barr@y...> wrote:

How can I interface an ESTOP external switch to mach2. I have the
PMDX.com parallel interface board and it does not seem to have an
estop connection? Can I specify in mach2 which parallel port pins
will be the estop (such as in the case of using a 2nd parallel

port)?

Thanks,

George: You need to decide what conditions will cause an E-stop and
what signals you have available when that condition occurs. Remember
that any signal to the parallel port on the PC has to be ground
referenced to the PC. If the signal is a fault signal from a motor
drive you have to make sure it's ground is common with PC (Step and
DIrection) ground and if not you need to consider using an
optoisolator or relay as isolation.

In a lot of the systems the e-stop signal back to MACH2 is more of
a "information" signal than an action signal. It is good practice to
employ a hard wired e-stop system that is independent of computer
control. It is common to wire things like hard limit switches and
front panel mushroom buttons to external electronics that shut off
the power to the motors and sending a signal to MACH2 that a manual e-
stop has occurred.

My big red button(s) and table limits are all wired in series in a
normally closed condition (contacts closed when switch not activated)
and that is used to hold in the coil voltage on a small 12VDC 4PDT
relay. Any activation and the relay releases. One set of the small
relay contacts drives the coil of the large contactor for DC supply
to all my motors, another set uses a normally closed pair that are
open during normal run conditons to feedback to the parallel port
(computer e-stop) and a third drives a big red lamp on the front
panel. The relay contacts isolate the PC from any outside
voltages/noise. Since my big contactor has DPDT contacts I have a
low ohm power resistor that gets clamped across the motors when the
DC is interrupted acting as a dynamic brake.

MACH 2 will let you monitor any parallel port input pin as e-stop.

Tom C