Document ID: chunk:federal_register_of_legislation:F2021C00477:body:0:p59
Version: federal_register_of_legislation:F2021C00477
Segment Type: other
Provision Reference: 
Character Range: 154974–157890

manufacturer, but made open for inspection at the time of type approval.
3.2. Description of the functions of "The System"
 A description shall be provided which gives a simple explanation of all the control functions of "The System" and the methods employed to achieve the objectives, including a statement of the mechanism(s) by which control is exercised.
3.2.1. A list of all input and sensed variables shall be provided and the working range of these defined.
3.2.2. A list of all output variables which are controlled by "The System" shall be provided and an indication given, in each case, of whether the control is direct or via another vehicle system. The range of control (paragraph 2.7.) exercised on each such variable shall be defined.
3.2.3. Limits defining the boundaries of functional operation (paragraph 2.8.) shall be stated where appropriate to system performance.
3.3. System layout and schematics
3.3.1. Inventory of components
 A list shall be provided, collating all the units of "The System" and mentioning the other vehicle systems which are needed to achieve the control function in question.
 An outline schematic showing these units in combination, shall be provided with both the equipment distribution and the interconnections made clear.
3.3.2. Functions of the units
 The function of each unit of "The System" shall be outlined and the signals linking it with other Units or with other vehicle systems shall be shown. This may be provided by a labelled block diagram or other schematic, or by a description aided by such a diagram.
3.3.3. Interconnections
 Interconnections within "The System" shall be shown by a circuit diagram for the electrical transmission links, by an optical-fiber diagram for optical links, by a piping diagram for pneumatic or hydraulic transmission equipment and by a simplified diagrammatic layout for mechanical linkages.
3.3.4. Signal flow and priorities
 There shall be a clear correspondence between these transmission links and the signals carried between units.
 Priorities of signals on multiplexed data paths shall be stated, wherever priority may be an issue affecting performance or safety as far as this Regulation is concerned.
3.3.5. Identification of units
 Each unit shall be clearly and unambiguously identifiable (e.g. by marking for hardware and marking or software output for software content) to provide corresponding hardware and documentation association.
 Where functions are combined within a single Unit or indeed within a single computer, but shown in multiple blocks in the block diagram for clarity and ease of explanation, only a single hardware identification marking shall be used.
 The manufacturer shall, by the use of this identification, affirm that the equipment supplied conforms to the corresponding document.
3.3.5.1. The identification defines the hardware and software version and, where the latter changes such as