AS IEC 61131.6:2014 pdf free

AS IEC 61131.6:2014 pdf free.Programmable controllers Part 6: Functional safety
software controlling the operation of the FS-PLC or one of its subsystems
Note 1 to entry: The embedded software is supplied by the FS-PLC manufacturer installed in the FS-PLC. The user has no direct access to embedded software. The FS-PLC manufacturer develops or writes embedded software to control his FS-PLC. This may, for example, control the communication subsystem or the interpretation of the program developed by the user in the engineering tools.
Note 2 to entry: Another term for embedded software.
Note 3 to entry: Firmware can be either safety related or non-safety related.
NOTE 1 As shown in a), a functional unit is able to be viewed as a hierarchical composition of multiple levels,each of which might in turn be called a functional unit. In level (i), a “cause” might manifest itself as an error (a deviation from the correct value or state) within this level (i) functional unit, and, if not corrected or circumvented,might cause a failure of this functional unit, as a result of which it falls into an “F” state where it is no longer able to perform a required function (see b)). This “F” state of the level (i) functional unit might in turn manifest itself as an error in the level (i-1) functional unit and, if not corrected or circumvented, might cause a failure of this level (i-1) functional unit.
NOTE 2 In this cause and effect chain, the same thing (“Entity X”) is able to be viewed as a state (“F” state) of the level (i) functional unit into which it has fallen as a result of its failure, and also as the cause of the failure of the level (i-1) functional unit. This “Entity X” combines the concept of “fault” in IEC 61508 series and ISO/IEC 2382-14，which emphasizes its cause aspect as illustrated in C) ,and that of “fault” in IEC 60050-191,which emphasizes its state aspect as ilustrated in d). The “F” state is called fault in IEC 60050-191, whereas it is not defined in IEC 61 508 series and ISO/IEC 2382-14.
NOTE 3 In some cases, a failure or an error might be caused by an external event such as lightning or electrostatic noise, rather than by an internal fault. Likewise, a fault (in both vocabularies) may exist without a prior failure. An example of such a fault is a design fault.AS IEC 61131.6 pdf free download.