A system for setting addresses includes a master device, a plurality of slave devices, and a bus. The master device includes a broadcasting module, a reading module, a responding module, an address assigning module, and a first judging module. Each slave device includes a performing module and a requesting module. The broadcasting module is configured to send messages to the slave devices. The performing module is configured to put the slave device be in an address setting mode. The reading module is configured to read a time assignment for each slave device from a timing module. The requesting module is configured to send an address request. The responding module is configured to respond to the address request. The address assigning module is configured to assign an address to the slave device. The first judging module is configured to check if all the time windows for the slave devices have elapsed.