STC MRDI Service manual

TB-2017234-RH01 1
Figure 1 - Connecting the Transmitter to the 2600-
020 AEI
Controller
Technical Bulletin
© 2017 Southern Technologies Corporation (STC). All rights reserved.
Bulletin Number: TB-2017234-RH01 Date Published: 08 22 2017
Summary: Operation Guide for the Model 2600-180 & 2600-190 MRDI Transmit and Receiver.
☐Critical (Affects safe operation of system) ☒Informational
Distribution List: NA
Description
The MRDI transmitter and portable receiver units are
wireless devices developed by Southern Technologies to
assist with wheel sensor alignment for the 2600-020 AEI
Controller or the MRDI system. When used with the AEI
Controller, the top four LEDs indicators (TO5-TO8)
represent sensors TO1-TO4.
The Transmitter Unit activates when plugged into the
AEI Controller. The Receiver Unit indicates the current
state of each connected wheel sensor and provides a
means to remotely monitor status changes while
making precise adjustments at trackside.
The maximum working distance between the
transmitter and receiver is approximately 150 feet
(45.72 meters) line of sight. The AEI Controller
provides power to the Transmitter Unit. The
Receiver operates from a 9-volt battery.
Directions for Use
1. Apply power to the transmitter and receiver
units. As shown in Figure 2, connect the
Transmitter Unit to the 2600-020 AEI Controller or
MRDI using the supplied flat cable. Switch on the
Receiver Unit soon after connecting the
transmitter. The units will automatically pair with
one another as indicated by the flashing red Link
LED, which is located on the receiver. The Link LED
blinks continuously when the units are in
communications with each other, but will stop
when out of range. If the units do not pair, see the
section on pairing later in this document.
2. Relocate the transmitter outside of the building
for additional range if necessary. Figure 4 represents
a suggested location for the transmitter.
Figure 2 - MRDI Transmitter and Receiver Units

TB-2017234-RH01 2
3. Locate and place the 2600-800 Wheel Sensor Gauge across the rails such that the large gauge plate
is positioned directly over the Tiefenbach wheel sensor. Make sure the gauge is properly seated on the
railhead as shown below in Figure 3.
Figure 3 - 2600-800 Wheel Sensor Gauge Placement
4. At the bottom of the wheel sensor, unscrew the two knurled protective plastic nuts from the
adjustment screws. Locate the brass adjustment tool that came packaged with your Tiefenbach wheel
sensor. Screw on the adjustment tool and tighten without pushing the adjustment screw out of its
adjustment protector. Push the adjustment tool upwards to unlock the protection mechanism.
CAUTION: Excessive force to the adjustment screw can cause damage to the sensor.
5. Calibration should begin with sensors in the
inactive state (LED indicator located on the Receiver
Unit, associated with wheel sensor, should be off). If
necessary, deactivate the sensor by reducing
sensitivity (turn the adjustment screw to left). Each
element of the dual sensor should be set to the
“activation threshold” with the target (large-gauge
plate) in place.
Note: Be sure Link LED on the Receiver Unit is
blinking the entire time while performing calibration.
6. Slowly turn the adjustment screw to the right
until the sensor just activates as indicated by the
associated LED on the Receiver Unit. Next, set the
second wheel sensor to the “activation threshold” in
a like manner.
7. Repeat procedure as necessary with each
remaining wheel sensor connected to the AEI
Controller.
The wheel sensors are now calibrated. Remove the
adjustment tool, replace the knurled nut, and lightly
tighten.
Figure 4 - Suggested Location for Transmitter

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Transmitter/Receiver Pairing
Southern Technologies performs initial pairing and ships product as a paired set. A paired set should
link with each other within a few seconds after being turned on. The following instructions provide
guidance for initial pairing for replacement units or in the unlikely event that re-pairing is necessary.
1. Remove the two Phillips screws and the cover from each unit. Figure 5 shows the internal circuit
boards of the receiver and transmitter.
2. With both units powered up, press and release both Pairing Pushbuttons simultaneously. The
Link LED on the receiver should begin to blink rapidly after a few seconds when paired.
3. Carefully replace covers. Do not over tighten screws.
The units will automatically pair each time they are subsequently powered up.
Figure 5 - Receiver and Transmitter without Cover
Transmitter Specifications
Frequency range: 902-928 MHz
FCC & Industry Canada compliant
RF Power Output +10dBm (10mW)
Operating temperature -40 to +85C
Receiver Specifications
Frequency range: 902-928 MHz
Sensitivity (-112 dBm at 1.2 kBaud, 915 MHz 1% packet error rate)
FCC & Industry Canada compliant
Operating temperature -40 to +85C
LINK LED
Pairing Pushbutton