SIGM20 Automatic Signal Controller

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Automatic signal control via Loconet!

The SIGM20 is an automatic controller for  eight signals. It  sets the signal state automatically according to the state of the trackwork (e.g. points), other signals and block occupancy detectors. It does this automatically, without any other computers involved: so no PC is required to operate the railway. The board can control simple blocks, simple and complex junctions ....automatically.

The SIGM20 drives LED signals directly. Via optional adapters it drives incandescent lamp signals or semaphore signals controlled by Tortoise point motors. The behaviour for each signal is programmed: thereafter it operates automatically without needing a PC to be present on the layout.

Simple block behaviour:

More complex junction behaviour:

SIGM20 Functions

Functions of the board include:

  • Controls up to 10 signals:

    • The SIGM20 drives either eight, 3-aspect signals or six, 4-aspect signals
    • Two more signals can be driven by an optional self assembly add-on board.
    • LED signals: these can be 2, 3 or 4 aspect, or "searchlight" type;
    • Incandescent lamp signals can be driven using optional adapters
    • Semaphore signals operated by Tortoise motors can be driven using optional adapters
    • NEW - simulation of "soft" lighting & dimming of lights: brightness ramps up or down over approximately half a second for more realistic looking signal lamps.

  • Signals can be of two basic types:

    • controlling a straightforward block (with one "ahead" route);
    • controlling a diverging jucttion (where the route depends on the state of a point);

  • Automatic signal logic, controlled in response to DCC and LocoNet activity:

    • The signals go red when the block ahead of them is occupied - sensed by LocoNet messages from block detectors (e.g. BDL168);
    • Signals will be amber if the next signal ahead is red;
    • Signals go red if the trackwork is set against them (e.g. if a point is not set correctly);
    • Track can be set for running in both directions; signal state is then sensitive to the running direction active at the time;
    • Running direction can be set automatically by train movements, or by operator control
    • ......and many other functions.

  • Fully compatible with SIGM10 - the two can be mixed on a layout seamlessly;

  • NEW - Screw terminal connections to signals

  • All the logic to make this happen is entered through a simple user interface;

  • All the behaviour is determined by LocoNet & DCC messages.

Prices

£54 assembled & tested board.
Ordering Information

Order Online!

Documentation & Application notes

The manual for the board is available for download: follow this link

Please see our application note page for advice on how to use the board. Several guides are available there.

Information on an optional DTX8 board to drive two additional signals is available.

Signal Mast Types

The SIGM20 drives most signals that have LEDs. Using the optional S10HCA adapter board, it can drive signals using miniature incandescent light bulbs, and "Tortoise" type point motors for semaphore signals. It is able to represent the following kinds of signal:

  • 4 aspect: these are typical of UK main line signalling with red, amber, double amber & green aspects;

  • 3 Aspect: widely used everywhere with red, amber, green aspects;
  • 3 aspect with flashing amber state: typical of US practice;
  • 2 aspect, used on minor lines only.
  • In European signalling practice, separate "distant" signals are common. The SIGM20 can drive one "distant" signal type, with the signal becoming dark (no LEDs lit) if the "main" signal on the mast is green.

The board can drive model signals that have LEDs wired in both common cathode and common anode arrangements. It can also drive "searchlight" signals that have one visible lamp that can adopt red, amber or green aspects using bi-colour LEDs.

Programming

Determining and programming the signal logic is not difficult, but does require thought (and a well drawn track plan helps!). It is necessary to know beforehand which block detectors will make each signal go red, and under what other conditions signals will need to go red. For example a signal on a main line will need to go red if a point from a siding onto the main line  is set to let a train from the siding proceed.

Programming of the signal logic is ideally carried out via a PC: simply enter into the PC the details of the block detectors for each signal and the point states that must make signals go red, and the PC will download the programming through LocoNet. For those that don't have a PC at all it is possible to do this by hand and program using a programming track.

The PC program to configure the board is called Locoanalyse. It can be downloaded here and now has its own web page.  It requires an MS100 (at minimum) or a locobuffer (preferably) to connect between the PC and LocoNet.

The definitions of all of the configuration variables for the SIGM20 is separately documented. Most users that use the PC program will not need this information, but it is available for those that are interested. SIGM20 SV Documentation

How it Works

The SIGM20 operates as a loconet device in the same way a throttle does. Through LocoNet, the SIGM20 is able to sense the states of points & sensors and can decode the DCC accessory commands that go to accessory decoders. The SIGM20 generates LocoNet messages when signals change states so that other devices can "know" the state of any other signal.

Through LocoNet, the SIGM20 can sense the state of points even if they are operated by a different throttle. With any accessory decoder, operation of points by other throttles (e.g. DT300, DT400) will be detected & shown on the panel. This will also be true if a PC software program (e.g. Railroad&Co) operates the points, or if  a DCS100 route sets the points.

If the accessory decoder does support feedback (e.g. DAC10, DS54) then the correct point state can be detected even if a local pushbutton input to the accessory decoder is used to change its state.

Points don't need to have feedback microswitches on their tiebars: see here for details.

Support

In the first instance, please consult our Frequently Asked Questions for this board. Please note that free support will be provided for the function of the board only. Advice on signalling configuration and determining signal logic will not be provided free of charge: these are layout specific and require user involvement.

Stefan Trachsler has written an excellent "LocoNet Checker" program that identified and reports devices present on LocoNet. This program supports the SIGM20 and can be found here.

©CML Electronics Limited 2008
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