Page 2 of 42
BLOCKsignalling www.blocksignalling.co.uk
Introduction
The BLOCKsignalling Section Control Module is designed to protect a section of
track to prevent more than one train entering that section at one time (see later for
details of the Station Stop Modes).
At the entrance to the section there is a signal and a short isolated piece of track
which can be energised and de-energised by a relay built-in to the module. There is
also an infra-red sensor which is located below the track which is able to detect
trains passing the signal.
The isolated section of track is normally powered via the relay and the signal
normally shows a green aspect.
At the start of the section, the infra-red sensor is continuously looking for a trains
passing, and as soon as it detects one, it switches the signal to red and disconnects
the power from the isolated section of track, stopping any approaching train in front
of the red signal (see later for bidirectional running).
The module then uses a second infra-red sensor located at the exit from the section
of track to detect when the train has completely left the section.
When this is confirmed, the signal at the entrance to the block is switched from
danger back to green (if a 2-aspect signal is used). The isolated track section at the
entrance is also re-energised and any waiting train will then move away past the
signal.
If 3- or 4-aspect signals are connected, then information from the following blocks is
used to switch the signals to show yellow or double yellow. The interconnection
between the modules carries coded information of the status of the block ahead.
In 2-aspect mode, a Dapol signal can be driven via a relay connected to CH5 for
some of the modes (2, 7 and 8). There are also station stop modes. These are
discussed in further detail later.
Bidirectional Running
There are two programs for bi-directional running with 2-aspect signals.
The first uses both sensors to detect trains entering the section. When a train
enters, the signal outputs are set to red. The sensors are checked alternately.
When the train has completely entered, the module then begins checking both
sensors to see if a train leaves the section.
