NSM-3E Signal Monitor Unit
Operations Manual
Eberle Design Inc.
Page 5
maximum. Recurrent Pulse detection can be disabled with the RP DISABLE option switch,
see Section 3.4.
2.5
LEDGUARD
®
LED FIELD SIGNAL SENSING
The NSM-3E Signal Monitor can be configured to use a technique called
LEDguard
®
that is
designed to better monitor the characteristics of LED based signal loads. Each field signal
input is measured and compared to both a high threshold and a low threshold value to
determine Active / Not Active status. This differs from conventional operation where the
active threshold is picked according to the color of the field signal. Once the high and low
On / Off thresholds (Section 5.1) have been determined using the input RMS voltage, the
individual fault monitor functions use the appropriate threshold to determine if a fault
condition exists.
LEDguard
®
Green/Walk
Yellow
Red/Dont Walk
Conflict
Low
Low
---
Red Fail
High
High
High
Dual Indication
Low
Low
Low
Clearance
Low
Low
High
2.6 NON-VOLATILE FAULT MEMORY
The loss of AC+ power to the monitor will not reset a fault condition (Conflict, Dual
Indication, Red Failure, Clearance or a Voltage Monitor Fault if the 24V Latch or CVM
Latch options are enabled). The NSM-3E Signal Monitor stores the fault and channel
indicator status into non-volatile EEPROM memory. Should an AC+ power interruption
occur while the monitor is in the fault mode, then upon restoration of AC+ power, the
Output relay will remain in the fault mode and the correct fault and channel information will
be displayed. This fault mode is maintained until the monitor receives a reset command
from the RESET button or the External Test Reset input.
2.7 RESET INPUT DETECTION
This function prevents the cabinet controller from being operated with the monitor disabled
due to a faulty Reset button or External Reset input. The NSM-3E Signal Monitor monitors
the state of the front panel Reset button and the External Reset input. When a Reset
command is detected from either input, the NSM-3E Signal Monitor will enter the reset
mode with all indicators illuminated, the Output and Start relays energized, and monitoring
functions disabled. The monitor will then automatically enter the normal mode and begin
monitoring functions.
2.8 DISPLAY LED TEST
The monitor will illuminate all front panel LED indicators for 1000ms when a Reset
command is issued by the front panel RESET button. This function provides a way to check
the operation of all front panel indicators.
