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Team Digital, LLC
SIC24 - Signal & Indicator Controller |
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The SIC24 (Signal and Indicator Controller) is
uniquely suited to control various types of signals and indicators on a
layout or a CTC panel. It
can be used as a signal controller, to indicate block occupancy and
turnout position, and as a grade crossing gate controller with
flashing signals. Combinations of some of these features are
also possible. The SIC24 is compatible with many DCC systems*
(see below).
• Built-in logic for automatically controlling signals using block detection • Configurable to model many signaling systems • Control SE8C signals • Computer not required, but can be used with one Control indicators on your layout or CTC panel • Block detection • Turnout status • Crossing gate and flashers Provides 24 outputs • Drives up to eight 3 LED signal heads with common anode or common cathode • Drives Bi-color LED searchlights with 2 or 3 leads. • Drives Tortoise TM switch machines for turnout control • Drives Tortoise TM switch machines for semaphore signal control including the middle yellow aspect. Provides 8 inputs • For local turnout control. • For occupancy sensors • For turnout feedback sensors Simple inter-board wiring • Serial bus reduces system wiring • Digitrax LocoNet® compatible Simple basic setup • Built-in setup configuration options • "Smart Programming" in conjunction with self programming The SIC24 sends and receives switch command, switch position feedback and sensor/block detection messages. It uses these same type messages to communicate between multiple SIC24s and to determine signal states. Since all communication is done over a serial bus, the number of wires to implement a signal system is greatly reduced. The serial bus is based on Digitrax’s LocoNet® and some features are unique to a Digitrax system. However, a Digitrax DCC system is not required for operation or programming. The SIC24 is compatible with LocoNet® block detectors such as the Digitrax BDL16 or detectors connected to its inputs such as the Team Digital DBD2 . A block diagram at the bottom of the page shows the general features with examples of various input and output devices. MSRP - 54.95 USD Available at these Dealers Manual in PDF format - 400K Board size: 2.2" X 4.0" Application Information Download an interactive simulation PC version: SIC24_siml.zip 900K Mac version: SIC24_sim68k.sit 1500K Support Tools |
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| Operation: The SIC24 has 24 outputs. Each output can drive an LED and can be assigned a specific function. For signal control, a three color aspect signal will require three outputs if each aspect is to be individually controlled. Typical signal control is based on some set of rules or logic to turn each LED 
on. Consequently, some logic is required to turn on and off each
output. In order to accomplish this, the SIC24 has a logic cell
that controls each output. The logic cell determines if it's
output will be on or off. When the logic cell is true the output
is on. When it is false the output is off. The logic cell
contains three logic elements, A, B and C. When all the logic
elements are true, the logic cell is true and the output is on.
Otherwise, the logic cell is false and the output is off. Each
logic element can be assigned to be a block state, a switch state or
a signal state. The concept of the logic cell allows the SIC24 to
drive a variety of signal types. See figure 1 for a diagram of a
basic logic cell. |
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| An illustration of Automatic Block signaling
(ABS) using a three color aspect signal can show how the
logic cell works. For any given direction, when a block is
occupied its signal is red and the following block signal is yellow
if the following block is not occupied. If neither of the blocks
is occupied, then the signal is green. |
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| Here is a simple example of ABS block signal
logic using B and S to represent block and signal respectively.
B2 is the block after B1. That is, the train is traveling from B1
to B2. S1 is red when B1 is occupied. S1 is yellow when S2 is red and S1 is not red. S1 is green when S1 is not yellow and not red. S2 is red when B2 is occupied. Six outputs of the SIC24 are assigned for the two signals. Three outputs for each signal. Each output driving an LED. Output 1 – S1R – signal one red Output 2 – S1Y – signal one yellow Output 3 - S1G – signal one green Output 4 – S2R – signal two red Output 5 – S2Y – signal two yellow Output 6 – S2G – signal two green |
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| A logic cell controls each output. So
each logic cell is configured to cause the output to respond to the
conditions as defined above. When all logic elements that
have been defined are true, the logic cell is true and the
output is turned on lighting the LED. Logic Cell 1 (output 1, S1R) Logic element A – B1 occupied Logic element B – NU Logic element C – NU Logic Cell 2 (output 2, S1Y) Logic element A – output 1, S1R not on Logic element B – output 4, S2R on Logic element C - NU Logic Cell 3 (output 3, S1G) Logic element A – output 1, S1R not on Logic element B – output 2, S1Y not on Logic element C - NU Logic Cell 4 (output 4, S2R) Logic element A – B2 occupied Logic element B – NU Logic element C - NU Logic Cell 5 (output 5, S2Y) ** this output is not used in this example Logic element A – NU Logic element B – NU Logic element C - NU Logic Cell 6 (output 6, S2G) Logic element A – output 1, S2R not on Logic element B – output 2, S2Y not on Logic element C - NU |
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| Each of the SIC24 outputs is assigned an
address, so whenever an output changes state a sensor type serial bus
message is sent with the address and state. So a logic cell can
use the logic state of an output as part of its logic. Some of the logic cells in the above example required more than one logic element to achieve the desired response. Both the conditions for element A AND element B had to be met before the output was on. As in the case of Logic Cell 2 (output 2, S1Y) in order for it to be true (on), output 1 had to be false (NOT on) and output 4 had to be true (on). These two elements are combined by AND logic. All three logic elements can be combined with one of four different logic  schemes. The four
combination are A OR B OR C, (A OR B) AND C, (A AND B) OR C and A AND B
AND C. An additional feature provides for control of the output. The output can be controlled so that when the logic cell is true the output is on, has a delayed turn on, is inverted or flashes. See figure 2 for a diagram of the complete logic cell with output control. It is important to note that when the logic cell tells the output to be on, that simply enables the output control to define what the output actual does. For example, it the output control is set to flash, the output will flash when the logic cell is true. The logic cell does not cycle from true to false each time the output flashes. The same holds true for a delay. The logic cell output is not delayed, only the output itself. |
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| In some cases three logic elements in each logic
cell may not be enough to implement the required logic. In these
cases the logic cell of one or more unused outputs can be utilized for
addition logic capability. |
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| The SIC24 has eight inputs. Each input can
be configured to send a switch command, switch position feedback or
sensor/block detection serial bus message. The inputs are compatible
with many stand-alone block detectors with noise filtering. Each
input can be configured to send a message on a rising, a falling
or a change of state signal. Unique signal schemes can be
implemented using the SIC24 by connecting outputs to inputs,
particularly if
an input is configured to send a message on a rising or falling state. |
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| Digitrax's SE8C has a unique address for each of
it's signals. One of the SIC24 configuration options enables one
of these unique addresses to be sent whenever a logic cell goes true.
Thus, using it's build in logic the SIC24 can turn on and off SE8C
signals in much the same way as it controls it's own outputs. The SIC24 does have limitations. It can not handle every possible signal scheme as a PC computer can. However, it does provide for signal and indication versatility with its logic capability. |
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| Programming: The SIC24 can be very challenging to program because of it's logic capability. To assist in programming, there are several built-in setup options. The setups are implemented using "Smart Programming" in conjunction with self programming. By entering several switch commands from the throttle, one of the setups is selected and configured. Once selected, the logic is automatically determined and all the required CVs programmed. The SIC24 comes pre-programmed for block signaling (ABS) of three aspects per signal which is one of the setups. "Smart Programming" can be done via the main track or via LocoNet®. Programming in page mode can be done using the programming track or via LocoNet®. Ops mode programming is also available via LocoNet®. CV read back using the programming track may work in some cases, but it is not supported by Team Digital because it is not reliable. Compatiblity: The SIC24 is not compatible with the Atlas, Backmann or MRC (except Prodigy Advance) DCC systems because they do not support accessory commands or can not program the number of CVs in the SIC24. |
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