STC Smartscan NG2, Manual

Page: 31 / 133

EUD-2018086-00 Rev.3, SmartScanNG² User's Guide for Wayside Enclosure Components, 14 May 2021
31
The LEDs can indicate that the relay has failed to activate when a control signal is applied, as
shown in the table below. In the table, a shaded area means that an LED is lit. An unshaded
area means that an LED isn't lit. Only seven of the possible combinations of lit LEDs are listed
below. All other combinations are invalid and indicate a system problem.
Shutter
Control
LED Shutter
Output
LED Heater
Control
LED Heater
Output
LED
Explanation
On Off Off Off Invalid. The shutters are being commanded to open,
but the relay isn't responding with shutter voltage.
On On Off Off Normal if a train is present. Invalid if a train isn't
present.
Off On Off Off Invalid. No shutter signal, but the shutter voltage is
present.
Off Off On On Normal if a train isn't present and the outside
temperature is cold. Invalid if a train is present or if
the outside temperature is warm.
Off Off On Off Invalid. The heaters are being commanded to turn
on, but the relay isn't responding with heater voltage.
Off Off Off On Invalid. No heater signal, but the heater voltage is
present.
Off Off Off Off Normal if a train isn't present and the outside
temperature is warm. Invalid if a train is present or if
the outside temperature is cold.