Harman Kardon SIG2.0 Owners Manual - Page 6

SIGNATURE BUS PROTOCOL MASTER DOCUMENT Revised 2-24-98 Preamble Target Byte Device Type Target Unit ID Source Device Type Source Unit ID Data Length Command Modifier Command Byte Data Byte(s) The Source Unit ID is a byte that distinguishes which unit of a given type the message is coming from (i.e. CD player #1 versus CD player #2). The Unit ID is set in the menu system of the unit that the message is coming from, default = 01h. If you are using more than one of any given unit, you will need to modify this byte. Checksum Byte Preamble Target Byte Device Type Target Unit ID Source Device Type Source Unit ID Data Length Command Modifier Command Byte The Data Length is a word representing the total number of bytes (including Command Modifier and Command bytes, but not the Data Length byte itself or the Checksum byte) in the data portion of the message. Minimum length is 02h. Data Byte(s) Checksum Byte Preamble Byte Target Device Type Target Unit ID Source Device Type Source Unit ID Data Length Command Modifier Command Byte Data Byte(s) The Command Modifier is a byte that distinguishes what type of command is being sent. HEX Command Type 01 Action request 02 Action response Checksum Byte Preamble Byte Target Device Type Target Unit ID Source Device Type Source Unit ID Data Length Command Modifier Command Byte PTrhoevCidoems amdadnitdiobnyatleiinsfothrme aactitoionnrethqautiriesddbesyirtehde.Command byte. Data Byte(s) Checksum Byte Preamble Byte Target Device Type Target Unit ID Source Device Type Source Unit ID Data Length Command Modifier Command Byte PTrhoevDidaetsaabdydtietsiocnoanlsiinsftoorfmiantfioornmraetqiuoinretdhabtyisthreeqCuoirmedmtaoncdobmyptel.ete the Command. The Data bytes are detailed throughout the rest of this document. Data Byte(s) Checksum Byte Preamble Byte Target Device Type Target Unit ID Source Device Type Source Unit ID Data Length Command Modifier Command Byte Data Byte(s) PTrhoevCidheescakdsduimtioinsaal binyftoerwmhaotisoenvraelquueirceodnfbiyrmthse/vCoiodms mthaenvdalbiydtiety. of a received message. It is computed by adding up all of the bytes Preamble through the last Data byte, and then taking the 1s complement of the lower eight bits of that sum (i.e. add up all the bytes, truncate to eight bits, and invert each of the bits). If the result equals 7Eh, add 01h. See the page 7 for an example. Checksum Byte Page 6 of 20