Communication system

A communication system, comprising:

• a control device as a master;
• and
• a plurality of control devices as slaves sequentially connected via a bus to the master on a post-stage side of the master,
• wherein
• the master includes a first transmitter including a first pull-up resistor and a first transistor that are connected in series between an application end of a power supply voltage and an application end of a ground potential,
• the slaves each include
• a second transmitter including a switch and a second pull-up resistor that are disposed between an application end of the power supply voltage and the bus and a second transistor disposed between the bus and the ground potential,
• a constant current supply disposed between the bus and the application end of the ground potential or between the application end of the power supply voltage and the bus, and
• an identification current detection unit disposed, in the bus, on a post-stage side of a node at which the constant current supply is connected to the bus,
• the communication system is configured to be capable of executing an address assignment process including
• a first process for detecting presence/absence of an identification current input by means of the identification current detection unit when the constant current supply has generated an identification current output with the switch and the second transistor in an off state, and
• a second process for repeatedly executing the first process while, with respect to a slave among the slaves that has had the identification current input detected therein, stopping generation of the identification current output thereafter, and assigning an address to a single slave among the slaves that has not had the identification current input detected therein, and
• the communication system is also configured to be capable of executing the address assignment process while excluding a slave among the slaves that has had the address assigned thereto.