Re: [CAD_CAM_EDM_DRO] Limit Switch Installation

jmw@... wrote:

> Are limit switches typically wired in series (normally closed) in
> the (PMDC) axis motor power circuit.
>
> I would assume so with this type of motor since the switch should
> stop the motor in case all other safeguards (software, etc) fail.
>
> But a switch rated for 15AMPS 90VDC is going to be the size of a shoe
> box? What up? Do people just run the cigarette-pack-sized switches
> (e.g. 24VDC 1AMP) and hope they don't trip em very often?

You don't generally connect the limit switches to break the full power
feed to the drives. You connect normally closed emergency switches
in series, and have them operate a power relay to cut the power,
disable servo amps, engage the braking resistors, etc. You would
normally wire the emergency circuit to shut off the spindle motor and
coolant systems, too.

I have a drawing of the emergency circuits I'm using with the
Servo to Go card and servo amps at
http://www.artsci.wustl.edu/~jmelson/EMC.html as the 4th picture,
and schematic that follows.

Jon