AS IEC 61131.6:2014 pdf free download – Programmable controllers
1 Scope
This Part of the IEC 61 1 31 series specifies requirements for programmable controllers (PLCs) and their associated peripherals, as defined in Part 1 , which are intended to be used as the logic subsystem of an electrical/electronic/programmable electronic (E/E/PE) safety-related system. A programmable controller and its associated peripherals complying with the requirements of this part is considered suitable for use in an E/E/PE safety-related system and is identified as a functional safety programmable logic controller (FS-PLC). An FS-PLC is generally a hardware (HW) / software (SW) subsystem. An FS-PLC may also include software elements, for example predefined function blocks. An E/E/PE safety-related system generally consists of sensors, actuators, software and a logic subsystem. This part is a product specific implementation of the requirements of the IEC 61 508 series and conformity to this part fulfils all of the applicable requirements of the IEC 61 508 series related to FS-PLCs. While the IEC 61 508 series is a system standard, this part provides product specific requirements for the application of the principles of the IEC 61 508 series to FS-PLC. This Part of the IEC 61 1 31 series addresses only the functional safety and safety integrity requirements of an FS-PLC when used as part of an E/E/PE safety-related system. The definition of the functional safety requirements of the overall E/E/PE safety-related system and the functional safety requirements of the ultimate application of the E/E/PE safety-related system are outside the scope of this part, but they are inputs for this part. For application specific information the reader is referred to standards such as the IEC 61 51 1 series, IEC 62061 , and the ISO 1 3849 series.
5.2.2.1 General
Security threat and hazard analysis are normally necessary for safety-related applications to protect against intentional attacks or unintentional changes. Security can be achieved by establishing appropriate security policies and measures such as physical (for example mechanical, electronic) or organizational measures. Where safety related communications are part of the FS-PLC there is the possibility of inadvertent changes to the parameters of network devices. Safety related communication devices shall have protections against inadvertent changes. Where applicable, the requirements for overall security defined in IEC 62443 shall be followed.
5.2.2.2 Security assumptions for ensuring functional safety and SIL capability
The basic security policy for the security environment(s) of the FS-PLC, according to the complexity of the equipment, should address the following security services:
– logical access controls to, and between, the FS-PLC, including human-machine interfaces. Such logical control is restricted to a known community of users who are approved by management to access one or more of the devices. Commonly, logical access is restricted to a small group of users who install, maintain and administer those services and granted on a role basis to selectively access, change and/or use specified information.
– management controls so that within a particular security environment there is a common approach to the management and administration of the security policy, with a single authority having overall responsibility.
– physical controls to limit unauthorized access to the FS-PLC (including backup materials, cabling, connections).