IEC 62280-1 Ed. 1.0 b:2002

Applicable to safety-related electronic systems using a closed transmission system for communication purposes. Gives the basic requirements needed in order to achieve safety-related communication between safety-related equipment connected to the transmission system. Not applicable to existing systems which had already been accepted prior to the release of this standard. However, as far as is reasonably practicable, this standard shall be applied to modifications and extensions to existing systems, subsystems and equipment.