A transmitter and a receiver are paired that use the same power line and power module. The transmitter associates an identification number with a command message so that a receiver can ascertain that a command message is intended for the receiver. The transmitter uses the time from the power up to the first zero crossing of the AC signal to generate a matching seed for both transmitter and receiver. The transmitter generates an identification number by incrementing a counter each incremental time interval between power up and the occurrence of the first zero crossing of the AC signal and sends the generated identification number to the paired receiver after power up but before a predetermined time interval. The receiver stores the generated identification number and compares the stored identification number with a received identification number that is received in a subsequent command message.