Division 2.2 Description of the functions of the safety instrumented system

A description shall be provided which gives a simple explanation of all the control functions of the safety instrumented system and the methods used to achieve the objectives, including a description of the mechanism(s) by which control is exercised including:

1. (a)

   A list of all input and sensed variables and their working range;

2. (b)

   A list of all output variables that are controlled by the safety instrumented system and an indication, in each case, of whether the control is direct or via another vehicle system. The range of control exercised on each such variable shall be defined;

3. (c)

   Where appropriate to system performance, limits defining the boundary of functional operation.