The SD-004 three aspect signal slave module is used to operate signals that are fitted with light emitting diodes (LED) for lamps. It connects directly to the central control unit (SD-001).
When the central control unit receives a command it decodes it and sends a data signal to the SD-004 slave unit which then changes the colour of the signal depending on the command sent.
Up to four of these slave units can be connected to a central control unit.
The three aspect signal slave module switches one signal in response to the data sent from the central control unit. One central control unit and four two aspect signal slave modules can control a total of four signals.
The SD-004 three aspect signal slave module supplies the correct voltage and current directly to the LEDs. No separate resistors are needed.
The three aspect signal slave module obtains power to drive the LEDs from the central control unit, no separate power supply is required.
The three aspect signal slave module uses two accessory decoder addresses for each signal.
When a command to change the aspect of a signal is sent from the comamnd station, the central control unit receives the command via the track bus. When a command is received the central control unit decodes the command data packet to determine the accessory address and if a match is found the central control unit sends a signal to the slave unit. The three aspect signal slave unit then sends a data signal to the track signal and the lights change to red, green or yellow depending on the commands sent to it.
If an address match is not found the command is ignored and no data signal is sent to the slave unit and the signal does not change.