Specifications

Section 1: Introduction
1-9
DOOR SWITCHES
A door switch senses whether a door is open or closed. A door switch interfaces to the Alto 818
via a monitor input. Through the database setup, a door switch can serve a number of functions.
It can be used to indicate a door which is held OPEN TOO LONG, exceeding the time period set
with the DOOR command. Similarly, if a door switch changes state from closed to open without
a valid access decision made by the ACU, a DOOR FORCED OPEN message can be generated.
When anti-passback is enabled, the card holder status can be programmed to change only if the
door switch indicates that the door has been opened.
REQUEST-TO-EXIT
A request-to-exit, REX, signal may be used to trigger the unlocking of a door or to inform the ACU
that a door is to be opened without a valid signal from a sensor, thereby preventing a DOOR
FORCED OPEN message from being generated. REX devices are frequently used on doors which
use a sensor only on the entry side.
When a REX signal is used to unlock a door, the open time interval is the same as when access
is granted through the sensor on the same door. The time interval may be restarted by repeatedly
activating the REX input for the door. If a REX signal is generated but the door is not opened, it
will relock at the end of the programmed unlock time. Just as with a door unlock triggered by a
valid card key presented to a sensor, the door will relock as soon as it is opened.
REX devices can be pressure-sensitive mats, panic bars, motion detectors, push buttons or a
number of other devices. The REX signal is interfaced to the Alto 818 via a monitor input.
1.3.6 ANTI-PASSBACK
If only the entrances to a controlled area are sensor-controlled, it may be possible for a key holder
to pass back his or her card key to an unauthorized individual who would then be able to use it to
enter the controlled area. The Alto 818 provides anti-passback control to prevent this. To use anti-
passback, all entrances and exits must be controlled by sensors. Command keys must be
presented alternately to an entrance and an exit; successive use of an entrance or exit constitutes
an anti-passback violation. Two types of anti-passback operation are available: Hard and soft.
While an area which uses anti-passback control must have both entrance and exit sensors, exits
should also be capable of being opened from the inside without use of a command key in emergency
situations. National, state, and local fire and life safety codes should be checked to verify if the
system design complies.