8
West
approach
detector
GND
OUT
Center
block
detector
GND
OUT
East
approach
detector
GND
OUT
GND
2
1
OUT
Figure 12 – External detector wiring (NCE BD20 shown)
Grade crossing bell
The
Grade Crossing Pro/2
can control a grade crossing bell sound module in two ways. The preferred way, and less
expensive option, is to plug in one of the bell modules we offer (#BELL-CL, #BELL-MD, #BELL-FA, #BELL-GS). If you
use one of these modules the
Grade Crossing Pro/2
will fade the sound off when shutting off the bell. There are two sockets
on the board to accept the module as shown in Figure 13a below. Carefully install the bell module by lining up the pins on
the bottom of the module to the mating sockets on the
Grade Crossing Pro/2
board. Note that when the module is properly
installed the bell module label will have the printing oriented in the same direction as the
Grade Crossing Pro/2’s
main chip.
Also, there will be two open socket locations along the top end of the lefthand socket. A properly installed bell module is
shown in Figure 13b below. The bell module requires an 8Ω speaker connected to the SPKR outputs as shown in Figure 13b.
You can adjust the volume of the bell sound using the potentiometer labeled VOLUME next to the SPKR terminals.
Figure 13a - Location for bell module
8Ω
Figure 13b – Bell module installed
Figure 14 shows the wiring for an external grade crossing bell sound module. Shown is the ITT sound module version from
2018 through the date on this document; contact us if you have a different version! You will need a 6 conductor ribbon cable
(available from us, part number X-CABLE) to make the connections. The black connector end plugs onto the 6 pin header
labeled “EXPAND” on the
Grade Crossing Pro/2
board. Make sure that the red stripe on the cable is closest to the edge of
the board; there is a white stripe printed on the board to the left of the 6 pin header as a hint! Pin 1 (red stripe) of the cable
prDC power to the bell module while pin 6 of the cable provides the “ground” connection to the bell module when it
is turned on by the
Grade Crossing Pro/2
. Note that you must install a small wire jumper between the two terminals on the
bell module labeled SW. Finally, connect any 8 ohm speaker to the bell module. The ITT sound modules have their own
volume control; the volume control on the
Grade Crossing Pro/2
does NOT affect an external bell module!
