A system for automatically addressing serially connected slave devices, the system comprising: a master device including a serial communication transceiver; multiple slave devices (204A, 204B, 204C), each slave device including a serial communication transceiver (206A, 206B, 206C), an address input port (214A, 214B, 214C), an address output port (216A, 216B, 216C), and a controller (208A, 208B 208C), the controller (208A, 208B 208C) in communication with the serial communication transceiver (206A, 206B, 206C), the address input port (214A, 214B, 214C) and the address output port (216A, 216B, 216C); a serial communication wiring bus (212A, 212B) connected between the serial communication transceiver of the master device and the serial communication transceivers (206A, 206B, 206C) of the multiple slave devices (204A, 204B, 204C); and at least one digital address line connected between the address input ports (214A, 214B, 214C) and the address output ports (216A, 216B, 216C) of the multiple slave devices (204A, 204B, 204C) in a daisy chain arrangement, characterised in that each controller (208A, 208B 208C) is configured to: receive a pulse-width modulation or pulse-frequency modulation signal from a previous one of the multiple slave devices (204A, 204B, 204C) in the daisy chain arrangement via the address input port (214A, 214B, 214C), the pulse-width modulation or pulse-frequency modulation signal corresponding to an address of the previous one of the multiple slave devices (204A, 204B, 204C) in the daisy chain arrangement; determine an address for the slave device comprising said controller according to the received PWM or PFM signal; and transmit a PWM or PFM signal to a subsequent one of the multiple slave devices (204A, 204B, 204C) in the daisy chain arrangement via the address output port (216A, 216B, 216C), the transmitted PWM or PFM signal indicative of the determined address for the slave device comprising said controller and different than the received PWM or PFM signal; wherein the master device is configured to transmit a save command to at least one of the slave devices via the serial communication wiring bus (212A, 212B) to lock the address determined by the at least one slave device. a master device including a serial communication transceiver; multiple slave devices (204A, 204B, 204C), each slave device including a serial communication transceiver (206A, 206B, 206C), an address input port (214A, 214B, 214C), an address output port (216A, 216B, 216C), and a controller (208A, 208B 208C), the controller (208A, 208B 208C) in communication with the serial communication transceiver (206A, 206B, 206C), the address input port (214A, 214B, 214C) and the address output port (216A, 216B, 216C); a serial communication wiring bus (212A, 212B) connected between the serial communication transceiver of the master device and the serial communication transceivers (206A, 206B, 206C) of the multiple slave devices (204A, 204B, 204C); and at least one digital address line connected between the address input ports (214A, 214B, 214C) and the address output ports (216A, 216B, 216C) of the multiple slave devices (204A, 204B, 204C) in a daisy chain arrangement, characterised in that each controller (208A, 208B 208C) is configured to: receive a pulse-width modulation or pulse-frequency modulation signal from a previous one of the multiple slave devices (204A, 204B, 204C) in the daisy chain arrangement via the address input port (214A, 214B, 214C), the pulse-width modulation or pulse-frequency modulation signal corresponding to an address of the previous one of the multiple slave devices (204A, 204B, 204C) in the daisy chain arrangement; determine an address for the slave device comprising said controller according to the received PWM or PFM signal; and transmit a PWM or PFM signal to a subsequent one of the multiple slave devices (204A, 204B, 204C) in the daisy chain arrangement via the address output port (216A, 216B, 216C), the transmitted PWM or PFM signal indicative of the determined address for the slave device comprising said controller and different than the received PWM or PFM signal; wherein the master device is configured to transmit a save command to at least one of the slave devices via the serial communication wiring bus (212A, 212B) to lock the address determined by the at least one slave device.