7
IR component wiring
Please note that the IR emitter wiring is DIFFERENT
from the previous generation
Grade Crossing Pro
!
Figure 10 illustrates the wiring for
ONE
set of IR
components (shown for sensor location “WF”).
REPLICATE the same wiring for the three
remaining sensor inputs!
Four 68 ohm ¼ watt
resistors (Blue-Gray-Black color bands) are included
with the
Grade Crossing Pro/2
. When properly wired
the emitters will have a very faint red glow. You can
“see” the infrared light using your digital camera or
smartphone camera!
For safety reasons do NOT point
the IR emitter directly into your eye or stare at the
IR emitter!!!
The
Grade Crossing Pro/2
supports a
SETUP mode which can be used to verify proper
operation of the sensors. To enable this mode, you must
have the switch labeled SETUP in the ON/CLOSED
position as shown in Figure 7. In this mode the signals
will not flash. There are four sensor status LEDs; one
68 ohms
1/4 watt
Detector
Blue
wire
Black
wire
Emitter
Black
wire
White
wire
Figure 10 – IR component wiring
(WF input shown; replicate for WN, EN and EF inputs respectively)
near each of the four photocell sensitivity adjustment pots.
NOTE: The four adjustment pots have NO affect when using
either infrared sensor mode!
Do the following after you have connected power (see page 9) to the board: With nothing over
or blocking any of the IR components the red sensor status LEDs on the circuit board should all be OFF. Place a piece of
rolling stock at each detection location, one at a time, and confirm that the associated red sensor status LED turns ON. Don’t
forget to turn OFF the SETUP switch when finished!
Using an external detector
Use this sensor mode if you would prefer to use a different type of detector such as an NCE BD20 current sensing detector.
Any brand of detector should work provided that its output is an open collector, “active low” polarity, which means that
when a train is detected the output is pulled to ground. When no train is sensed the detector output is an open circuit or
“floating.” You will need 3 detection blocks or zones. Figure 11 shows how they would be partitioned. Figure 12 shows how
simple it is to connect the BD20 block detectors to the
Grade Crossing Pro/2
.
NOTE: The four adjustment pots have NO
affect when using this mode!
W E
WO ow
Crossing
section
East
approach
section
West
approach
section
Figure 11 – External detector zone partitioning
STOP
