To order, call 1-800-652-7276
e-mail: orders@ansaldo-sts.us
www.ansaldo-sts.com
p. 1
Wayside Signaling
Systems
Ansaldo STS USA
(Formerly known as Union Switch & Signal)
Rev. 4-11
MicroLok II Track Circuit PCBs
MicroLok II Track Circuit PCBs permit the system to perform the
critical function of train detection in railroad applications, both
along the mainline and interlocking locations. The MicroTrax
Coded Track Circuit PCB is part of a total track circuit system that
enables very long track circuits, accurate train detection
regardless of ballast conditions, and data-intensive through-the-
rails communications. The ECode Track Circuit PCB allows
MicroLok II systems to interface with most versions of the
Electrocode Track Circuit, thus expanding applications to more
territories and simplifying the transition to all-MicroTrax
operations. For railroad interlocking (e.g. end of siding), the OS
Track Circuit board provides a simple and reliable means of
detecting trains within the interlocking tracks (no track occupany
relays required).
Descriptions
“MicroTrax” Coded Track Circuit PCBs (N451910-0701, -7601, -7602, -
7603)
The MicroTrax Coded Track Circuit PCB provides an interface between
the CPU PCB vital microprocessor and MicroTrax style DC coded track
circuits. The MicroLok II CPU PCB monitors incoming coded track
circuit communications through this PCB, and interprets a loss of
communications (due to shunting of the signal by an approaching train)
as a track occupancy condition (train detection). Each Coded Track
Board monitors two adjacent track circuits simultaneously. The CPU
processes the occupancy inputs in the context of the entire interlocking
control scheme.
The generation track code signal is connected to the
rails through a Track Interface Panel consisting of a
transformer and a low impedance inductor (see RSE-
1D3). Eight front-panel LEDs on the board monitor a
variety of signals such as Master and Slave track
signal pulse transmissions and receptions (+/-) and
valid message confirmation.
ECode Track Circuit PCB (N17063901)
The ECode Track Circuit PCB enables MicroLok II
systems to be installed in territory equipped with
current and past generations of Electrocode track
circuits. This board interfaces with the MicroLok II
CPU PCB, where the actual processing of track
messaging and train detection indications are
performed. Both this PCB and its associated Track
Interface Panel (see RSE-1D3) are dual-capacity units
capable of handling two independent dc coded track
circuits.
The front panel of this board contains LEDs and
switches that permit on-site observation of track
signals, calibration and maintenance checks. By using
a pushbutton on the ECode Track Circuit PCB’s front
panel, users can view the transmitted/received codes,
receive current, transmit voltage and transmit current.
Rotary switches on the panel permit manual
adjustment of track code transmit levels for the two
controlled track circuits.
OS Track Circuit PCB (N451810-6701)
The On Switch (OS) Track Circuit PCB interfaces the
MicroLok II system to the OS track circuit at
interlocking applications requiring one OS transmitter
and two OS receivers (end-of-siding). An OS track
circuit is used to indicate the track occupancy status of
both the crossover track and the short section of
mainline track near the switch. Detection of the
presence of a train in either of these areas is used to
prohibit activation of the switch machine. Train
