889-2106-03
Model U-1400 Operations Manual Rev Apr 2020 Page
32
of 39
5.5
LOOP CHECK PASS / FAIL INDICATIONS
The Loop Check feature is enabled whenever the Loop Check Timer for a specific loop input
is set to a value between 1 and 255 minutes. When the Loop Check Timer has timed out, the
detector will automatically short the check loop to simulate vehicle detection. If the
percentage of inductance change is greater than or equal to -0.04%
∆
L/L, and the channel on
which the current loop check test is selected and being viewed on the LCD, the display will
show
PAS
.
If the percentage of inductance change caused by activating the check loop is less than -0.04%
∆
L/L, the detector will initiate its check loop verification process. The LCD screen will
display an indication of a pending state (
Pcl
) during the check loop verification. This screen
will flash for 55 seconds until one of three things happen; the check loop verification fails
(indication shown below -
Lcl
), the check loop(s) causing the check loop verification is (are)
connected or restored to a functional state (indication shown above,
PAS
), or the check
loop(s) causing the check loop verification is (are) turned off, i.e. the Loop Check Timer of
the loop(s) is set to 000.
If the check loop verification fails, the LED corresponding to that loop
channel will begin flashing at a three Hz rate. If the channel
corresponding to the check loop failure is selected and being viewed on the
LCD, the display will toggle between a screen showing
L
and
LOOP
FAIL
and a screen showing
Lcl
and
LOOP FAIL
with a 50% duty cycle
to indicate a that Loop Check failure has occurred. In addition, the loop
status will enter the Call state and the Health Status will enter the Fail
condition. A Loop Check failure will deactivate any Primary Vital Output
to which any loop input or Health Status is mapped. When the Health
Status of one or more loop inputs is (are) mapped to an Auxiliary Vital
Output, a loop check failure will deactivate the Auxiliary Vital Output.
Disabling the Loop Check feature (setting the Loop Check Timer to zero), powering down the detector, or resetting
the channel that failed the loop check test will clear the Loop Check failure. However, if the problem that caused
the Loop Check failure is not corrected, the channel will fail the next loop check test.
The Loop Check feature is suppressed if the loop has an open, a shorted, or a relative (±25%
∆
L/L) failure.
The detector will perform a loop check test on all programmed channels two seconds after start-up or two seconds
after a reset.
NOTE: If the Loop Check Timer is set to 000, the Loop Check function is off.
5.6
VITAL INPUT (VITAL IN) STATUS / FAIL INDICATIONS
Each of the four Vital Inputs has a dual color (green / red) LED which illuminates in various ways to indicate the
state of the Vital Input. When the LED is off, the Vital Input is deactivated (low voltage level). When the LED
LOOP FAIL
1
©
LOOP FAIL
1
©
Loop Check
Failure
1
©
Loop Check
Pass Indication
1
©
Loop Check
Pending
