Signals are short messages that can be exchanged outside the standard application messaging system. They do not require Input, Output or Pipe and can be sent in unicast mode (to a specific target), multicast mode (to a set of targets) or in broadcast mode (to everybody in the network).

They are used to report simple events such as status change, emergency commands, etc...

Signals can be sent from:

the CHAI, Direct and Broadcast;
Local Device (if the source of the signal is relevant), Direct and Broadcast;
Input, Directed to each source device;
Output, Directed to each destination device

They are identified by a number (CPNS::Enums::Signals) and organized in categories.

Some signals can be sent by applications to the CopperLan engine (e.g. CPNS::Enums::SIG_LearningCancel).