IEC/PAS 61784-3-18:2009(E) specifies a safety communication layer (services and protocol) based on CPF SNpFAMILY of IEC/PAS 62633 and IEC/PAS 61158 Type SNpTYPE. It identifies the principles for functional safety communications defined in IEC 61784-3 that are relevant for this safety communication layer. It contains an additional profile - SNpTYPE - which may be integrated into a future new edition of IEC 61784-3.