Transmitter/receiver circuit for protection circuit

A transmitter/receiver circuit comprising:

• a plurality of secondary batteries connected in series;
• a first protection circuit provided in a low voltage side of the plural secondary batteries and including
• a transmitter circuit configured to decrease a voltage of a binary signal to a level that is a first voltage lower than a cathode voltage of a first secondary battery connected to the first protection circuit;
• and
• a second protection circuit provided in a high voltage side of the plural secondary batteries and including
• a receiver circuit configured to receive the binary signal transmitted from the transmitter circuit via a wiring and including
• a shift part configured to increase the voltage of the binary signal to a level that is a second voltage higher than an anode voltage of a second secondary battery connected to the second protection circuit, and
• a detection part configured to determine that the wiring is disconnected when the voltage of the binary signal is higher than a reference voltage.