IEC 61784 3-6:2010 specifies a safety communication layer (services and protocol) based on CPF 6 of IEC 61784-1, IEC 61784-2 and IEC 61158 Type 8. It identifies the principles for functional safety communications defined in IEC 61784-3 that are relevant for this safety communication layer. This part defines mechanisms for the transmission of safety-relevant messages among participants within a distributed network using fieldbus technology in accordance with the requirements of IEC 61508 series for functional safety. These mechanisms may be used in various industrial applications such as process control, manufacturing automation and machinery. This second edition cancels and replaces the first edition published in 2007. It constitutes a technical revision. The main changes with respect to the previous edition are: updates in relation with changes in IEC 61784 3. This bilingual version published in 2011-11, corresponds to the English version published in 2010-07.