Page 5
FIG. 7: WIRING WITH INTEGRATED PUSH BUTTON AND TIMER (
AL-85852
)
12-28 VDC
POWER
SUPPLY
+
-
MAGNETIC LOCK
+
-
+
-
AL-85851
REX
INPUT
C
NC
ACCESS SYSTEM LOCK
CONTROL RELAY
R
ED
GRN
BLK
USE 1/2 SECOND TIME
SETTING WITH ACTIVE REX
(SEE SECTION 5)
IN+ D VICE
C1 NC1 NO1
AL-85852
PUSH BUTTON
WH
T
4.
BASIC OPERATION
When the
AL-85851
is first powered, its LED will flash twice quickly every second for
about 40 seconds. This is a self test and also permits the
AL-85851
to adjust itself
to the thermal environment that it “sees”. After this start up period, the LED will stay
green. If the self test fails during the start up period, the LED will begin to flash at four times
per second. This failure indication will continue indefinitely. If you see it, de-power the unit
for about 30 seconds and then re-power it. If the failure indication occurs again, replace the
unit. During the self test period the unit’s control outputs are in their “normal” conditions
(lock control-conducting; REX-relay deenergized).
In the event of a very brief power outage, the unit will not self test for 40 seconds but will
undergo a self test of 10 seconds before resuming normal operation. Note that the self test on
power up feature of the unit is the main reason why the
AL-85851
must receive constant
power.
With the jumpers in factory set condition and the unit past its self test, it will detect moving
objects at a different temperature than ambient. It will signal this detection by switching its LED
from green to red. The LED actually mirrors the state of the REX relay rather than the lock
control transistor.
You need to understand how the unit’s control outputs operate in a detection event. In the rest
condition (green LED on; no detection), the lock control transistor is conducting and the
REX relay is deenergized. When an object is detected, the REX relay energizes immediately.
This is to shunt alarm contacts or send a REX signal to an access control system. Fifty
milliseconds later, the lock control transistor switches off which releases the magnetic lock.
This brief delay is to make sure that the access control system has processed the REX signal so
that it won’t alarm if it is also reading lock status detection such as
the
Senstat feature. A lock
status signal will change state as soon as the lock is de-powered.
In factory set condition, the lock control transistor will remain off for four seconds after detection
has ceased (keeping the lock released). If, during the four seconds, the object moves again, the
detection condition will be maintained for another four seconds after this “new” detection ceases.
For the magnetic lock to resecure, four seconds must pass with no detection. This trailing
edge timing feature is for egress safety and reliability. Otherwise, it is possible for a person to
approach the door (thereby activating the
AL-85851
) but then stop moving for a brief moment
at the door. The detector would then reset and if the person then quickly lunged into the door
he could receive a bump as his motion could be quicker than the response of the detection to
this new movement. The four second timing feature virtually eliminates this potential problem.
Another operational safety feature is the fact that if power is cut to the
AL-85851
, the lock
safely releases so that a person wishing to exit is not trapped.
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800.323.4282
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