Rockwell Automation 1762-Lxxxx MicroLogix 1200 Programmable Controllers - Manual (Page 23)

Publication 1762-UM001G-EN-P - March 2011
Install Your Controller 2-9
Use Emergency-Stop Switches
When using emergency-stop switches, adhere to the following points:
• Do not program emergency-stop switches in the controller program.
Any emergency-stop switch should turn off all machine power by
turning off the master control relay.
• Observe all applicable local codes concerning the placement and
labeling of emergency-stop switches.
• Install emergency-stop switches and the master control relay in your
system. Make certain that relay contacts have a sufficient rating for your
application. Emergency-stop switches must be easy to reach.
• In the following illustration, input and output circuits are shown with
MCR protection. However, in most applications, only output circuits
require MCR protection.
The following illustrations show the Master Control Relay wired in a grounded
system.
TIP
Do not control the master control relay with the
controller. Provide the operator with the safety of a
direct connection between an emergency-stop
switch and the master control relay.
TIP
In most applications input circuits do not require
MCR protection; however, if you need to remove
power from all field devices, you must include MCR
contacts in series with input power wiring.