
Page 13 of 13
BLOCKsignalling
www.blocksignalling.co.uk
5. If the signal aspects do not light as expected, wire each output in turn to the
green output (with the other aspects not connected) to confirm that all the
aspects of the signal work when separately connected to the green channel.
If none of the aspects work when connected to the green channel it is likely
your signals are common-cathode signals which will not operate with this
module. If in doubt, check with the supplier of your signals.
6. If when the module is powered, the signal shows green, then immediately
switches to red, check there is not an obstruction in front of the sensor (such
as a tunnel roof).