Abstract: A monitoring system includes a slave device (4) and a master device (5). The slave device (4) superposes a current signal, which represents measurement data obtained by measuring each of one or more solar cell panels included in plural solar cell panels (P1 to P15) constituting a solar cell string (10), to a DC current path. The DC current path includes plural power lines (L1 to L14), a first trunk power line (21), and a second trunk power line (22). The master device (5) is connected onto the first trunk power line (21), second trunk power line (22), or both of the trunk power lines, and receives the measurement data from the slave device (4). Accordingly, the communication performance between the slave device and master device in, for example, a monitoring system that performs monitoring in units of a solar cell panel can be improved.

Abstract: Each transmitter (4) included in a first transmitter group (40A) transmits, on a first electric wire (2A), a current signal representing a change in current in accordance with a transmission bit sequence. Each transmitter (4) included in a second transmitter group (40B) transmits, on a second electric wire (2B) that is connected in parallel with the first electric wire, a current signal representing a change in current in accordance with a transmission bit sequence. A current detection unit (6A) outputs an electric signal representing a change in a difference current between a first current (IA) flowing through the first electric wire (2A) and a second current (IB) flowing through the second electric wire (2B). A receiver (5A) identifies and receives a reception bit sequence corresponding to the transmission bit sequence of each transmitter (4) included in the first and second transmitter groups, by processing the first electric signal.