Re: [CAD_CAM_EDM_DRO] E-Stop switch

P. J. Hicks wrote:

>Hi,
>
>When the proper input line (pin) is triggered Mach1 initiates an E-Stop condition.
>
>a. Is this (software triggered) the norm? I.e. shouldn't an E-Stop be a physical/mechanical/electrical sort of thing?
>
>

For safety reasons, there should be an all hardware e-stop circuit that
removes power from the
motor drives. This is much more important on servo systems than
steppers, as many failure
modes would cause stepper systems to stop moving, where failures might
cause a servo to
run away at high speed.

>b. I have read mention of removing all power when E-Stop is activated and seen pictures of the Big Red Switch on several controller cabinets. Does this mean complete removal of all power to the system both AC primary and DC motor power or one or the other?
>
>

I have a servo-driven machine, and the emergency stop circuit informs
the computer of the condition,
but also removes the raw DC motor power from the servo amps, and
connects a braking load to the
amps power input. It also shuts off the servo amps transistors. So, it
really stops the machine
through three different mechanisms, hopefully stopping the machine even
if there is at least
one failed component IN the e-stop circuit, such as a welded relay contact.

Generally, in CNC systems, e-stop stops motion. E-stop on old mainframe
computers removed power,
because the most likely emergency on those was fire.

Jon