Sending and receiving messages is easy:
And then in another plugin:
Explained:
SendMessage: First parameter is the target extension (usually this is the SID aka ShortName defined in ExpansionInit), in this case we are using "*" because that makes it broadcast to all plugins
second parameter is the message identifier
third parameter is a dictionary, this can hold anything you want
ReceiveMessageEvent: first we check the identifier so we know what to expect
Then we just read the dictionary as usual