Frequently Asked Questions:

SIGM20

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FAQ:
General
DAC10
DTM16
DTM30
SIGM10
SIGM20
LocoAnalyse

Ribbon Cables

 

My signals aren't responding properly

The following causes have been found to cause this kind of behaviour:

  • Is the LocoNet cable plugged into front of UP3 or similar utility panel? The front connectors are suitable only for throttles because the rail_sync signals (a version of the DCC track signal) is not passed out to the front connectors. The LocoNet cable must always be connected to the rear telephone connectors.

  • Are the LocoNet cables OK? We are aware of several instances where a LocoNet cable that passes a test with an LT1 tester is actually high resistance, affecting the messaging.

  • Is the jumper JP1 on the board removed? These should be REMOVED for normal operation, and only inserted for programming on a programming track.

  • Is the board's green LED lit? If not, this suggests a problem with LocoNet cabling, or the track power is currently switched off.

What sort of signals should I use?

The SIGM10 drives most signals that have LEDs. Using the optional S20HCA adapter board, it can also drive signals using miniature incandescent light bulbs. 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.

How do I set a serial number for a new processor?

Some users (e.g. beta testers) may be sent a new processor chip. This will have the SIGM20 firmware, but no serial number allocated. This needs to be set before the board can be used and programmed. DO THIS BEFORE DOING ANYTHING ON THE LAYOUT! A SIGM10 with unprogrammed serial number can be identified because its green LED flashes steadily after power up.

Full instructions for installing new processors can be found here.

A serial number is assigned by setting a point to THROWN (typically using a handheld throttle). To assign serial number=17, set point 17 THROWN.  The SIGM10 responds to the first point thrown command it sees. It is important not to operate the railway with an unconfigured board - because the first point operation is likely to program it.

Once the serial number has been programmed it can be changed using the "locoanalyse" software. Consequently setting to an erroneous value is not disastrous. However, the PC software will not be able to configure a board that has not had the serial number set initially.

What does the green LED tell me?

The green LED will be lit if all is well on the board and it is correctly decoding DCC packets from the LocoNet cable. In general if the track power is on, your green LED should always be on.

When the SIGM20 receives a DCC or LocoNet message that affects the signals it controls, the LED flickers off momentarily. This is provided to assist with layout setting up, so that users can tell that a command tot he board has been detected. For example if a signal is controlled by a sensor on a BDL16x board, then when that sensor changes state & puts a message onto LocoNet, the LED will flicker.

If the SIGM20 is powered up, track power is on and the green LED isn't on, it points to a problem in cabling between the SIGM20 and the command station. The following suggestions are offered:

  • Check that the SIGM20 has power properly applied.

  • Is the board correctly powered? SIGM20 boards should not share a transformer winding with the boosters, or with power fed to some other types of device e.g. DS54 or DAC10. This can lead to "ground loops" with short circuits introduced via the return path. There is more advice in the general FAQ.

  • Check that track power really is on.

  • Check that jumper JP1 is removed.

  • Check that the SIGM20 cable isn't connected into the front of a utility panel, e.g. UP3.

  • Check the integrity of the LocoNet cables between the SIGM20 and command station. Sometimes the connectors don't crimp properly, leaving a high resistance connection. An LT1 type tester doesn't always detect this!

4 Aspect Signals

The SIGM20 can drive eight, 3-aspect signals or six, 4-aspect signals: i.e. a total of 24 LED outputs. It is important to realise what is happening when 4 aspect signals are connected.

Firstly, the outputs can b selected between 3 aspec and 4 aspect for each "half" of the board independently. Outputs 1-4, and outputs 5-8, are separately selected; when 4 aspect is selected, the last signal in the bank does nor drive LED outputs. Some possible legal combinations therefore are:

  • Signals 1-4 are 3 aspect; signals 5-8 are 3 aspect

  • Signals 1-3 are 4 aspect; signals 5-7 are 4 aspect (signals 4 & 8 not being used)
  • Signals 1-4 to be 3 aspect;signals 5-7 are 4 aspect (signal 8 not used)
  • Where 4 aspect signals are used, signals 4 & 8 respectively don't drive LEDs. However their logic is still programmed and they generate LocoNet messages as if they were driving signals. Thery can be used as "Virtual" signals where complex logic is needed.

The outputs for each signal are now labelled A-B-C-D for each signal. The manual shows which output provides each output.

 

©CML Electronics Limited 2008
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