BS EN 54-21:2006 pdf download

BS EN 54-21:2006 pdf download.Fire detection and fire alarm systems一 Part 21: Alarm transmission and fault warning routing equipment.
7.4 Electrical and other design requirements
7.4.1 The processing of signals shall give the highest pnority to the transrnession of fire alarms (item E of Figure 1 of EN 54-1:1996) or fault warning (item J of Figure 1 of EN 54-1:1996). If both E and J are operated in the same routing equipment, then the highest priority should be given to fire alarms
7.4.2 The availability of the power supply for the routing equipment shall be as a minimum on the same level as the avallabdity of the power supply for the CIE required by EN 54-4.
7.4.3 Transitions between the main and the stand-by power sources shall not change any indications and/or the state of any outputs, except those refating to the power supplies.
7.4.4 If the routing equipment has provison for disconnecting or adjusting the mn or the stand-by power source, this shall only be possible at access level 3 or 4.
7.5 Integrity of transmission paths
7.5.1 A fault m any transmission path between the routing equipment and the transmission network (as defined in EN 50136-1-1) shall not affect the correct functioning of the routing equipment or any other transmission path,
7.5.2 If the routing equipment is designed to be used with a power supply (item L of Figure 1 of EN 54-
1:1996) contained in a separate enclosure, then an Interface shall be provided for at least two transmission paths to the power supply, so that a short circuit or an interruption in one does not prevent the supply of power to the routing equipment.
7.6 Accessibility of indications and controls NOTE See EN 54-2:1997, Annex A
Access levels shall be provided on the routing equipment, from access level 1 (most accessle) to access level 4 (least accessible). Manual controls and other functions shalt be grouped on the appropriate access level, as specdled In EN 54-2:1997, 12.6.
77 Indications by means of lIght-emIttIng Indicators
7.7.1 Mandatory indications from light-emitting indicators shall be visible in an ambient light intensity up to 500 tx, at any angle up to 22,5 from a line through the indicator perpendicular to its mounting surface:
at 3 m distance: the indication of the supply of power,
— at 0,8 m distance: other indications.
7.7.2 If flashing indications are used, the on- andlor the off-periods shall be not less than 0,25 s and the
frequencies of flash shall be not less than 0.2 Hz for fault indications
7.8 Colours of indications
The colours of the general and specific indications from light-emitting indicators shall b€ yellow for indications of fault warnings and red for the indication of the acknowledgement.
7.9 Testing of Indicators
All mandatory visible indicators at the routing equipment shall be teslable by manual operation at access level 1 or 2.
110.3 Software design
In order to ensure the reliability of the routing equipment the following requirements for software design shall apply:
a) the software shall have a modular structure.
b) the design of the interfaces for manually and automatically generated data shall not permit invalid data to cause an error in the program execution,
C) the software shall be designed to avoid the occurrence of a deadlock in the program flow.
7.10.4 Program monitoring
7.10.4.1 The execution of the program shall be monitored as under 7.10.4.2 or 7.10.4.3. It routines associated with the main functions of the program are no longer executed, this shall be indicated at least as a common fault warning as ii Clause 5.
7.10.4.2 If the program executes In one processor, the execution of the routines as In 7.10.4.1 shall be monitored by a monitoring device as in 7.10.4.4.
7.10.4.3 If the program executes ii more than one processor, the execution of the routines as in 7.10.4.1 shall be monitored in each processor. A monitoring device as in 7.10,4.4 shall be associated with one or more processors, and at least one such processor shall monitor the functioning of any processor not associated with such a monitoring device.
7.10.4.4 The monitoring devico of 7.10.4.2 and 7.10.4.3 shall have a time base independent of that of the monitored system. The functioning of the monitonng device, and the signalling of a fault warning, shall not be prevented by a failure in the execution of the program of the monitored system.
7.10.4.5 In the event of a system fault as specified in 7.10,4.1 or 7.10.6. those parts of the routing equipment affected shall enter a safe state not later than the indication of the system fault. This safe slate shall not result in the false activation of mandatory signals.
7.10.5 The storage of programs and data
7.10.5.1 All executable code and data necessary to comply with this European Standard shall be held In memory which is capable of continuous. non-maintained, reliable operation for a period of at least 10 years.