The two primary approaches for communication networks in safety systems
are the white channel and the black channel. The white channel is
essentially an entire communication scheme that is designed from the bottom
up for safety applications. Of course, all of this specialized equipment
requires certification and implies added cost, including hubs switches, and
so on. The black channel, which comes from the “black box” concept and
uses a regular transmission system and regular network hardware. The
safety layer is essentially built into the network and exists between the
communication stack and the application according to the IEC
62280-1 standard.