Patent ID: 7228373

Claim:
A serial digital communication system, comprising: a master device having an input/output (I/O) node for sending messages to a chain of slave devices; and a plurality of slave devices connected serially to form a chain extending from a first slave device to a last slave device, each slave device after said first slave device being subsequent to the slave device immediately preceding it in said chain, each of said slave devices having a first node and a second node, the first node of the first slave device in said chain connected to said master device's I/O node, the second node of each slave device connected to the first node of the subsequent slave device in said chain except for the last slave device in said chain, the second node of which is left unconnected; said master device arranged to originate messages, each of which is sent to a respective one of said slave devices, each of said messages comprising: a ‘distance to target device’ value which represents the number of slave devices between said master device and the target slave device, and a data packet containing data to be conveyed between said master device and said target slave device; each of said slave devices arranged to: receive a message originated by said master device at its first node, determine if the ‘distance to target device’ value in said message is equal to a pre-selected target address value which indicates that said slave device is the target device, and when said slave device is not the target device: increment or decrement the ‘distance to target device’ value by a pre-selected fixed number, and transmit the modified message to said second node; and when said slave device is the target device: receive the data in said data packet.