Re: Control Pendant/Panel layout for your comments

--- In CAD_CAM_EDM_DRO@yahoogroups.com, wanliker@a... wrote:

> In a message dated 10/17/2003 12:42:48 AM Mountain Daylight Time,
> jeff@w... writes:
> It works as well as
> other schemes (like the charge pump circuit), but only requires a
> switch latched relay contact.
> In my thoughts it works much better as no power, no movement. And

no auto

> start after any power outage either. Too much solid state stuff

fails in a

> shorted mode and in some cases can power things up. That can be

very dangerous.

> And in my mind there has to be one E Stop that isolates

power,,,,,,,,period.

> bill

Bill is right. E-stop should NOT be initiated by the control
software. E-stop should manually kill power to the motors and inform
the software through feedback it has done so. By using a latching
relay as the DC power control any condition that even momentarily
interrupts the power to the relay shuts things down. By wiring the
limit swiches in series Normally Closed and making it part of e-stop
protects the machine from running or starting if a fault condition
exists.