ability of a system that, by adequate technical or organizational measures, prevents from hazards either deterministically or by reducing the risk to a tolerable measure

Note 1 to entry:  Equivalent to functional safety.

FSV

values which are issued or delivered instead of process values when the safety function is set to a fail-safe state

Note 1 to entry:  In this document, the fail-safe substitute values (FSV) are always set to binary “0”.

one-bit value used to indicate a certain status or control information

GUID

128-bit number used to identify information in computer systems

Note 1 to entry:  The term universally unique identifier (UUID) is also used.

Note 2 to entry:  In this document, UUID version 4 is used.

MNR

means used to ensure the correct order among transmitted safety PDUs and to monitor the communication delay

Note 1 to entry:  Instance of sequence number as described in IEC 617843.

Note 2 to entry:  The MNR starts at a random value and is incremented with each request. It rolls over to a minimum threshold value that is not zero.

Note 3 to entry:  The transmitted MNR is protected by the transmitted CRC signature of the ResponseSPDU.

predicate meaning that the respective object is a “standard” object and has not been designed and implemented to fulfil any requirements with respect to functional safety

non-safety-related part of the implementation of this document which maps the SPDU to the actual OPC UA services

Note 1 to entry:  Depending on which services of OPC UA are being used (e.g. Client/Server or PubSub), different mappers can be specified.

PV

input and output data (in a safety PDU) that are required to control an automated process

attribute (bit or Boolean), indicating whether the corresponding value is valid or not (e.g. being a fail-safe substitute value)

SafetyAC

communication partner in a unidirectional safety link

Note 1 to entry:  A SafetyAutomationComponent can be a SafetyProvider (data source), a SafetyConsumer (data sink), or both.

entity (usually software) that implements the data sink of a unidirectional safety link

application data transmitted across a safety network using a safety protocol

Note 1 to entry;  The safety communication layer does not ensure the safety of the data itself, but only that the data is transmitted safely.

entity (usually software) that implements the data source of a unidirectional safety link

randomly generated authenticity ID which is used to safely authenticate SafetyProviders having the same SafetyProviderID

Note 1 to entry:  Together with the SafetyProviderID, it is an instance of connection authentication as described in IEC 617843.

user-assigned, locally unique identifier which is used to safely authenticate SafetyProviders within a certain area

Note 1 to entry:  Together with the SafetyBaseID, it is an instance of connection authentication as described in IEC 617843.

Note 1 to entry:  All SafetyProviders within an area such defined may share an identical SafetyBaseID.

part of the transmission system (implemented in hardware and software) that is not implemented according to any safety standards

Note 1 to entry:  This document is using the services of the standard transmission system to transmit prebuilt safety packets.