This part of the IEC 61784-3 series explains some common principles that can be used in the transmission of safety-relevant messages among participants within a distributed network which use fieldbus technology in accordance with the requirements of IEC 61508 (all parts)1 for functional safety. These principles are based on the black channel approach. They can be used in various industrial applications such as process control, manufacturing automation and machinery.

This part and the IEC 61784-3-x parts specify several functional safety communication profiles based on the communication profiles and protocol layers of the fieldbus technologies in IEC 61784-1, IEC 61784-2 and IEC 61158 (all parts). These functional safety communication profiles use the black channel approach, as defined in IEC 61508. These functional safety communication profiles are intended for implementation in safety devices exclusively.

NOTE 1 Other safety-related communication systems meeting the requirements of IEC 61508 (all parts) can exist that are not included in IEC 61784-3 (all parts).

NOTE 2 It does not cover electrical safety and intrinsic safety aspects. Electrical safety relates to hazards such as electrical shock. Intrinsic safety relates to hazards associated with potentially explosive atmospheres.

All systems are exposed to unauthorized access at some point of their life cycle. Additional measures need to be considered in any safety-related application to protect fieldbus systems against unauthorized access. IEC 62443 (all parts) will address many of these issues; the relationship with IEC 62443 (all parts) is detailed in a dedicated subclause of this document.

NOTE 3 Implementation of a functional safety communication profile according to this document in a device is not sufficient to qualify it as a safety device, as defined in IEC 61508 (all parts).

NOTE 4 The resulting SIL claim of a system depends on the implementation of the selected functional safety communication profile within this system.

NOTE 5 Annex C explains the numbering scheme used for the technology-specific parts (IEC 61784-3-x) as well as their common general structure.

NOTE 6 Annex D provides a guideline for the assessment and test of safety communication profiles as well as safety-related devices using these profiles.