LOGIC RAIL Grade Crossing Pro User manual

L OGIC
TECHNOLOGIES
R AIL
"Sophisticated
Model Railroad
Electronics"
TM
21175 Tomball Pkwy Phone: [phone]
Suite 287 email: [e-mail]
Houston, TX 77070 http://www.logicrailtech.com
Grade Crossing Pro
- Infrared detection version
Instructions
Revised 7/4/18
Getting started
Thank you for purchasing a Logic Rail Technologies product! Please familiarize yourself ith all the instructions prior to
installing this board.
The Grade Crossing Pro (GCP) provides prototypical operation of a grade crossing. Four pairs of Infrared (IR) emitters and
detectors are used for bidirectional train detection. Detection is achieved hen the IR beam from the emitter reflects off the
underside of the train back do n to the detector. Despite the use of infrared components you could still encounter false
triggering from overhead lighting. This is usually eliminated with angled sensor mounting Figure 5b) and/or proper
sensor sensitivity adjustment page 4). This version of the GCP must be powered from either a 7-9V AC or 9-12V DC
power source such as our 12VPSR). Do NOT exceed these limits! The layout of the signals and IR components is
illustrated at left belo . The illustration on the right sho s a side vie of the IR detection method.
The GCP operates as described next. An eastbound (left to right) train ill cause the signals to begin flashing hen the WF
sensor is activated. Approximately 2 seconds later the gate motor output ill turn on and the gates ill move do n (if
present). The signals ill continue to flash even if it clears WF as long as the train reaches WN ithin 35 seconds. Assuming
the train does this and then subsequently reaches EN the signals ill continue flashing. Approximately 2 seconds after the
last car of the train clears EN the gate motor output ill shut off and approximately 3 seconds later the signals ill stop
flashing. If the train had not reached WN ithin 35 seconds of clearing WF then the GCP ill assume the train has reversed.
This “timeout” ill cause the gate motor output to shut off and the signals ill stop flashing (~3 seconds after gate motor
shut off). Similar behavior exists for a estbound train ith respect to EF, EN and WN (shut off occurs after the last car
clears WN).
You should make all of the connections to the GCP before applying po er to it. You can mount the GCP any here it is
convenient underneath your layout using the four mounting holes provided. The holes ill accept #4 scre s; do not enlarge
the holes as damage to the circuit board can result and your arranty ill be voided!
The GCP board has 2 configuration s itches on it. Each s itch is described belo .
Switch Name Meaning when OFF/OPEN Meaning when ON/CLOSED
SETUP GCP is in normal operating mode GCP is in sensor setup mode
LP No Lamp Persistence (TrueLamp2) Lamp Persistence (TrueLamp2) enabled
The SETUP s itch is used to set your sensors’ sensitivity. Refer to page 4 for the sensor setup procedure. The LP (Lamp
Persistence) s itch, also kno n as TrueLamp2, feature provides realistic fading in and out of signals hile flashing. This
feature can be used ith either LED-based or bulb-based signals. Note that due to the technical nature of ho this is
accomplished, it may potentially shorten the life of bulb-based signals; there are no concerns ith LED-based signals!
The next t o pages provide the iring details for the crossing signals and gates (if applicable). The crossing signals fall into
3 categories:
• Tomar’s LED-based signals
• Other brands (including scratch-built) of LED-based signals such as Walthers
• Bulb-based signals
Refer to the appropriate section for the type of signal you are connecting to the GCP.

Wiring Tomar’s LED-based crossing signals
Tomar’s LED-based crossing signals are pre- ired in a common anode (positive) manner. Since these are dual-sided signals
(i.e. LEDs on both sides of each signal mast) there are 2 yello and 2 red ires (one from each LED’s cathode) and one
common hite ire. Figure 1 belo sho s you ho to ire ONE signal. The GCP ill support t o dual-sided signals; if
you are using t o signals then simply replicate the iring sho n for the second signal. Note that EACH LED connection
requires a current limiting resistor. The value of the resistor is dependent upon the voltage applied to the GCP. You can use
Table 1 to determine the resistor value. You can al ays substitute a ½ att resistor for a ¼ att resistor.
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Figure 1 – Wiring Tomar’s LED-based signals
Voltage applied to GCP Resistor Value
9V DC 390 ohm, 1/4W
12V DC 470 ohm, 1/4W
7V AC 390 ohm, 1/4W
9V AC 560 ohm, 1/4W
Table 1 – Current limiting resistors
Wiring other LED-based crossing signals including Walthers)
If you are using another brand of LED-based crossing signals, or are scratch-building your o n, you MUST ire them in a
common anode (positive) manner. Figure 2 belo sho s you ho to ire ONE single-sided signal; if you are using multiple
signals, or dual-sided signals, simply duplicate the iring sho n for the additional LEDs. Each of the GCP’s signal outputs
can handle loads up 180mA (~12 LEDs). Note that EACH LED connection requires a current limiting resistor. The value of
the resistor is dependent upon the voltage applied to the GCP. You can use Table 1 above to determine the resistor value.
Note that some of the resistors can be ¼ att hereas others must be ½ att. You can al ays substitute a ½ att resistor for
a ¼ att resistor but you CANNOT substitute a ¼ att resistor for a ½ att resistor!
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Figure 2 – Wiring LED-based crossing signals
Wiring bulb-based crossing signals e.g. NJ International)
Crossing signals constructed ith bulbs do not have a polarity like LED-based signals do. Ho ever, some bulb-based signals
may be pre- ired ith a common ire. If your signal does not, then you ill simply create a common connection from one
lead of each bulb (it doesn’t matter hich lead is used). Figure 3 belo sho s you ho to ire ONE single-sided bulb-based
signal. The GCP ill support t o dual-sided signals; if you are using multiple signals, or dual-sided signals, simply duplicate

the iring sho n for the additional bulbs. Note that current limiting resistors are sho n. These are only required IF the
voltage provided to the GCP is greater than the rating on the bulbs; most bulbs are rated at 12V AC or DC but you should
check the instructions that come ith the signal. If the GCP voltage source exceeds the bulb rating then add current limiting
resistors as sho n belo ; e recommend a value of 100Ω, ¼ att.
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Figure 3 – Wiring bulb-based crossing signals
Wiring crossing gates
The GCP ill directly drive a slo motion motor that
is typically used ith crossing gates such as those
from Tomar. Figure 4 sho s ho the GCP is
connected to a motor; the GCP can drive a max of
two motors (one per gate if you prefer to use
separate motors). If the gates are raised hen the
signals are flashing and lo er hen the signals are
not flashing then you simply need to reverse the
motor connections. You can adjust the speed of the
gate motor on the GCP. Using a flat blade
scre driver insert it into the gate speed adjustment
pot (from the edge of the circuit board, not from the
center of the board). Turning the scre driver
clock ise ill increase the gate speed hile turning
the scre driver counter-clock ise ill decrease the
gate speed.
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Figure 4 – Gate Motor Wiring Tomar example)
NOTE: You must check the instructions for your gate motor to determine the maximum voltage that the motor can
accept. For example, Tomar uses Circuitron’s Tortoise™ which has a maximum voltage rating of 12V DC or AC. If
the voltage provided to the GCP is greater than the rating on the motor then you will need to add a current limiting
resistor we recommend a value of 390Ω, ½ watt) in the connection path between one of the GCP’s GM outputs and
the turnout motor.
Mounting and wiring the IR components
The IR components should be mounted bet een the rails. Drill t o 11/64” holes,
through the ballast, roadbed, and sub-roadbed. These holes should be located one tie
apart (Figure 5a) and drilled at approximately a 45 to 60 degree angle from horizontal as
illustrated in the side vie in Figure 5b. The benefit of mounting them at an angle is
reduced false triggering from overhead light and increased detection reliability in smaller
scales or irregular bottoms on rolling stock. For the smaller scales this drilling may end
up hitting the ties. Take your time so you don’t mangle them! Insert the leads of one IR
emitter ( hite and black ires) into one of the holes (it doesn’t matter hich one!) from
the top of your layout. Repeat for the IR detector (blue and black ires). The tops of the
components should sit no higher than the top of your ballast for optimal IR performance;
in some cases (e.g. false triggering) it may be necessary to locate the components a little
belo the ballast line. You can extend the leads ith similar (or larger) ire. We
recommend soldering and insulating these connections. We also recommend using
terminal blocks/strips since you’ll have multiple DC and GND connections to make.
Once you have ired the IR components and verified their operation you may ish to
put a dab of hite glue or silicone caulk here the ires exit the holes underneath the
layout. This ill help to hold the components in place; make sure you don't get any
substance (e.g. ballast or glue) on the top surface of the IR components as this may
prevent them from operating properly. In extreme cases here you may be getting
interference from overhead lighting you can mount the IR detector in some plastic or
metal tubing. You can also recess the IR detector slightly belo the ties and roadbed.
Figure 5a
Figure 5b

Figure 6 belo illustrates the iring for one set of IR components (sho n for sensor location “WN”). Use
the same iring
scheme for the three remaining sensor locations (WF, EN, EF). Four 180 ohm 1 Watt resistors are included ith the GCP.
WARNING: The 180 ohm 1 watt resistor may become hot to the touch – take care so that you don’t burn yourself!
When properly ired the emitter ill have a very faint red glo coming from it. You can also look at the emitter through a
digital camera and see the infrared light!
For safety reasons do NOT point the IR emitter directly into your eye or stare
at the IR emitter!!!
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Figure 6 – IR component wiring
The spacing bet een the outer sensors (WF and EF) and inner sensors (WN and EN) depends upon ho long of a
n approach
you ish to
define for the crossing. Ho ever, keep in mind that there is a 35 second timeout that the GCP uses. This me
ans
that if it takes more than 35 seconds for a train to cover the nearest inner sensor after clearing an outer sensor then the GCP
ill think the train has actually backed up and exited the detection section!
Sensor sensitivity setup
Along one edge of the board are four potentiometers that are labeled "WF", “WN”, “EN” or “EF”; these are referred to as the
sensitivity adjustment pots. For most lighting environments it is USUALLY sufficient to just leave these set midway in
their travel i.e. halfway between fully clockwise and fully counterclockwise). To determine if any adjustments need to be
made do the follo ing:
1. Remove all obstacles that may be covering the sensors. Verify that all four of the blue IR detector ires are
connected into their associated terminal on the GCP board.
2. Put the GCP board into SETUP mode by putting the s itch labeled SETUP in the ON/CLOSED position. In this
mode the signals and gates ill not operate!
3. Run a locomotive over each of the four detector locations pausing over each one. Verify that the red LED on the
GCP lights up hen the locomotive is covering a detector. If this orks correctly then STOP you are done! If not
continue to step 4.
4. Using a small flat blade scre driver turn all four adjustment pots to the midpoint in their travel as described above.
5. If the red LED on the GCP board is ON then remove each of the four blue detector ires from the GCP’s terminals
one at a time. As you remove a ire check the red LED. If it turns OFF hen you remove a particular ire then note
hich location (WF, WN, EN, or EF) caused the change. Then reconnect that same blue ire and turn the associated
adjustment pot slightly clock ise (right) until the red LED turns OFF. It may be necessary to repeat this as you
reconnect the disconnected blue ires!
6. One you confirm that the red LED stays OFF ith all four blue detector ires properly reconnected then you’ll need
to verify proper detection ith a piece of rolling stock. Confirm that the red LED turns ON and OFF off as you
move a boxcar over each of the four detector locations.
7. Exit SETUP mode by putting the SETUP s itch in the OFF/OPEN position. The crossing signals should no
operate properly. You may ish to repeat this procedure ith any other layout lighting conditions you operate under
(e.g. “daytime” vs. “nighttime”).
Power
The GCP accepts 7-9V AC or 9-12V DC po er. Po er consumption hen used ith LED-based signals is approximately
390mA; po er consumption hen using bulb-based signals is approximately 430mA. If you are only using a single GCP
then use the TWO AC terminals to provide po er (polarity doesn’t matter). CAUTION: Most AC or DC accessory terminals
on your throttle/po er pack exceed 12V and cannot be used ith the GCP! Ho ever, you can use those po er sources in
conjunction ith our 12VPSR hich ill provide 12V DC. If you are using more than one GCP you can po er them all from

a single 9-12V DC source as sho n in Figure 7 belo .
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Figure 7 – DC power
Controlling an external bell ringer circuit
The “TO” (Trigger Output) terminal on the GCP can be used to trigger an external bell ringer circuit. The “TO” is active
hen the gate motor outputs are on; it is an “open collector, active lo ” output hich means that it is at ~0V hen on and
looks like an open circuit hen off. Figure 8 belo illustrates ho to control Innovative Train Technology’s GL Series bell
module (introduced in early 2017). A common DC po er source is highly recommended; CONTACT US if you ish to use
an AC po er source! Pay attention to the order of connections on the ITT module! As sho n the bell module ill play its
sound file as long as the TO output is active. If the crossing is active for a long time (more than a minute) you may hear a
brief gap in the sound hen it reaches the end of its recorded loop and starts over again.
Note that if you have an older ITT module that does not match the photo below then please contact us for details on
connecting it to the GCP. You can also find those details in the Application Note “Interfacing to Innovative Train
Technology’s bell modules” under the Documents tab on http://www.logicrailtech.com.
DC Power
Source
RO LO GM TO TI
Grade Crossing Pro
1
Tr
ac
k
AC GND DC PWF PWN PEN PEF
+
GND
Jumper wire
Figure 8 – Bell ringer control
Multi-track grade crossings
There is an obvious tendency to just add additional sensors to handle additional tracks hen you have a multi-track grade
crossing. The problem ith this implementation is that the GCP cannot differentiate bet een t o trains traveling in opposite
directions on different tracks. As such it could easily get “confused” and not provide the prototypical sequencing (i.e. the
action starts hen the train covers a far sensor and the action stops hen the train clears the near sensor on the other side of
the crossing). If you ill have multiple trains traveling through the crossing area ( ith outer boundaries defined by the far
sensors) at the same time then you must use one GCP for each track. See the next section for details on ho to cascade
multiple GCPs. IF you operate your trains such that only ONE train can possibly go through the crossing area at a
time then you CAN simply add additional sensor sets available from us) for the additional tracks. In this
implementation you ill ire the additional sensors the same ay you did for their counterparts on the first track (i.e. per
Figure 6). So for example, the blue ire from ALL of the WN detectors ill connect to the PWN terminal on the GCP.

Cascading Multiple GCPs for multi-track grade crossings
The “TI” and “TO” terminals on the GCP are used for cascading multiple GCPs hen you have a multi-track crossing. You
must use one GCP per track and you MUST use the SAME DC po er source (as sho n in Figure 9 belo ) for all cascaded
GCPs. You ill denote ONE GCP as the “master” and the others as “slaves”. The master provides detection for one track
and receives “triggers” from the slaves and provides the signal and motor outputs; the slaves only provide detection via
their o n sensors and do not utilize their signal or motor outputs. Figure 9 illustrates the iring for a 3 track set up.
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Figure 9 – Cascading Multiple GCPs
Troubleshooting
If your signals do not flash hen a particular sensor is activated then you can perform the follo ing tests. First, perform the
sensor setup routine previously described. If one or more of the sensors does not function properly then you kno it is faulty. If
the sensors are OK then you might have a problem ith the GCP, the signals, or the iring bet een them.
If the red LED on the GCP board stays lit hen the GCP is in SETUP mode then there is a problem ith: sensor sensitivity,
sensor iring, or one of the chips on the GCP. First, double-check your sensor iring. A missing sensor connection (missing
ire or open circuit) ill be interpreted by the GCP as a cleared sensor. A shorted sensor (i.e. blue and black ires touching)
ill be interpreted by the GCP as an activated sensor. Next, put the GCP in SETUP mode (see page 1) and turn all four sensor
sensitivity pots completely clock ise (right). If the red LED goes out then simply complete the sensor setup process
continuing ith Step 4 on page 4. If the red LED is still lit then the problem is either a bad sensor or a faulty chip on the
GCP.
You can determine if the GCP sensing chip is orking correctly by TEMPORARILY disconnecting all blue sensor ires
from the GCP. If the red LED on the GCP is lit then its sensing chip is faulty (read on belo for details on replacing it). If, on
the other hand, the red LED on the GCP is no dark then connect each sensor input (PWF, PWN, PEN, PEF) to GND, ONE
sensor input at a time. An activated sensor appears to the GCP like a connection to GND so you are, in effect, mimicking an
activated sensor ith this test. If the red LED does NOT come on each time you make that temporary connection (make sure
you try all four sensor inputs!) then you have a faulty chip.
The chip that “processes” the sensor inputs is located closest to the sensor sensitivity pots. This chip is labeled “LM339”.
Replacements are available from us or you might find one from stores such as Radio Shack. To replace the chip you ill
need to gently pry it out of its socket using a flat blade scre driver. Take great care hen inserting the replacement chip so
that you don’t bend any of its pins underneath it. Make sure the text on the chip has the same orientation as the name “Grade
Crossing Pro” on the circuit board. Still having problems?! Please contact us for further assistance!
Warranty
This product is arranted to be free from defects in materials or orkmanship for a period of one year from the date of purchase.
Logic Rail Technologies reserves the right to repair or replace a defective product. The product must be returned to Logic Rail
Technologies in satisfactory condition. This arranty covers all defects incurred during normal use of this product. This
arranty is void under the follo ing conditions:
1) If damage to the product results from mishandling or abuse.
2) If the product has been altered in any ay (e.g. soldering).
3) If the current or voltage limitations of the product have been exceeded.
Requests for arranty service must include a dated proof of purchase, a ritten description of the problem, and return shipping
and handling ($7.50 inside U.S./$20.00 outside U.S. - U.S. funds only). Except as ritten above, no other arranty or
guarantee, either expressed or implied by any other person, firm or corporation, applies to this product.
Technical Support
We hope the preceding instructions are sufficient for ans ering any questions you might have about the installation of this
product. If you require technical support please do not hesitate to contact us by phone, mail and email; our contact information
can be found on page 1.