Host communications architecture

A data communications method for a plurality of communication devices including a host and a number N, N>=1, of clients in an electrically noisy environment, comprising:

• a) initiating a serial transmission of a data packet to a first downstream client without a separate clock signal line, said data packet including a plurality of bytes, a first subset of said plurality of bytes including an address portion of said data packet and a second subset of said plurality of bytes including a payload portion, said data packet having a start-of-packet identifier defined by a predetermined period of signal inactivity;
• b) receiving said data packet from a particular upstream communications device as a received data packet, an X of N client receiving from an X−1 client wherein said X=1 client receives said data packet from the host;
• c) retransmitting said data packet to a particular downstream communications device as a retransmitted data packet, said X of N client retransmitting to an X+1 client wherein the Nth client retransmits said retransmitted data packet to the host;
• said data packet having a transit time through said daisy-chain loop from a beginning of said transmission of said data packet from the host to a completion of said retransmission of said data packet from the Nth client to the host, said predetermined period of signal inactivity pre-established as less than said transit time;
• wherein said data packet receiving step a) includes, for each client:
• a1) receiving a transmission having an initial period of signal inactivity and a subsequent period of signal activity;
• a2) comparing said initial period of signal inactivity to said predetermined period of signal inactivity;
• and
• a3) decoding said subsequent period of signal activity as said received data packet when said initial period of signal inactivity has a predetermined relationship to said predetermined period of signal inactivity.

A data communications system in an electrically noisy environment, comprising:

• a plurality of communication devices, said communication devices including a host and a client communicated to said host using a daisy-chain loop wherein said daisy-chain loop originates at a first location on said host and terminates at a second location on said host and wherein said daisy chain-loop comprises a pair of conductor segments, a first conductor segment communicating said host to said client and a second conductor segment communicating said client to said host;
• said host including a serial communications master initiating a serial transmission of a data packet to said client, said data packet including a plurality of bytes, a first subset of said plurality of bytes including an address portion of said data packet and a second subset of said plurality of bytes including a payload portion, said data packet having a start-of-packet identifier defined by a predetermined period of signal inactivity;
• and said client including a serial communications servant that receives said data packet from said host as a received data packet and retransmits said data packet to said host as a retransmitted data packet, said data packet having a transit time through said daisy-chain loop from a beginning of said transmission of said data packet from said host to a completion of said retransmission of said data packet from said client to said host, said predetermined period of signal inactivity pre-established as less than said transit time, wherein each said serial communications servant includes a receiver to receive a transmission having an initial period of signal inactivity and a subsequent period of signal activity, and a comparator comparing said initial period of signal inactivity to said predetermined period of signal inactivity, said serial communications servant including a decoder decoding said transmission into a decoded address portion when said initial period of signal inactivity indicates, responsive to said comparison, that said subsequent period of signal activity includes said data packet.