An MCR zone uses two MCR ________ one on the initial MCR rung and one on the end MCR rung.

In an MCR (Master Control Relay) zone, it is essential to have a method of controlling the flow of logic within that section of the control program. The use of two MCR coils is necessary; one is placed on the initial MCR rung to activate the zone and the other on the end MCR rung to deactivate it.

When the initial MCR coil is energized, it allows the logic below it to operate, effectively enabling the controlling processes within that MCR zone. Conversely, upon reaching the end MCR coil, the logic is deactivated, thus stopping any further actions in that zone.

Having these two coils creates a controlled environment where the program can execute tasks only when the MCR zone is active, thereby ensuring that the logic is easily managed and preventing any unintended operations. The MCR coils function as gateways that determine which parts of the program are active at any given time.