IEC 61784-3-1:2007 specifies a safety communication layer (services and protocol) based on CPF 1 of IEC 61784-1 and IEC 61158 Type 1 and 9. It identifies the principles for functional safety communications defined in IEC 61784-3 that are relevant for this safety communication layer. This bilingual version (2014-12) corresponds to the English version, published in 2007-12.