scope:

Introduction

Point switch rails need to have moved fully to their correct positions before signalled movements are allowed over them. Detection is the means of checking if the points are in the right position. If the points are facing points, then the detection also checks that they have been locked in that correct position.

Where signals are mechanically operated, it is often convenient to have mechanical detection in series with the signal wire, but most installations nowadays are electrical, and this form of detection will be dealt with in this module.