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Data structure for the ICOM IC-R2 Scanner - OoCities

Data structure for the ICOM IC-R2 Scanner - OoCities

Data structure for the ICOM IC-R2 Scanner - OoCities

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This diagram clearly shows how data transmitted from <strong>the</strong> computer is reflectedback to <strong>the</strong> computer <strong>for</strong> monitoring of <strong>the</strong> transmission. The diagram alsoshows that radio data is also reflected back to <strong>the</strong> radio so that collisions can bedetected.Because <strong>the</strong> transmit-data line and <strong>the</strong> receive-data line are connected toge<strong>the</strong>r,<strong>the</strong> CI-V interface is connected in a wire-OR configuration. When <strong>the</strong> computertransmits a command, <strong>the</strong> command is automatically echoed back as receiveddata, followed by <strong>the</strong> radio's response to <strong>the</strong> command, if any. For example, if aneleven-byte command is transmitted to a device on <strong>the</strong> cable, and a six-byteresponse is sent, <strong>the</strong> computer will receive a total of seventeen bytes (11+6=17).This configuration allows devices on <strong>the</strong> cable to monitor <strong>the</strong>ir own transmissionsin order to detect interface collisions.A collision occurs when two or more devices transmit simultaneously. If acollision occurs, <strong>the</strong> command must be re-transmitted. The radio or computerthat is transmitting reads its own transmissions back from <strong>the</strong> communicationscable. If it detects that ano<strong>the</strong>r device has transmitted at <strong>the</strong> same time (i.e.<strong>the</strong>re has been a collision) <strong>the</strong> radio or computer stops transmitting, listens tomake sure that <strong>the</strong>re are no o<strong>the</strong>r data transmissions on <strong>the</strong> cable, transmits ajamming code (5 characters of value $FC), and retransmits <strong>the</strong> originalcommand.Question: does <strong>the</strong> cloning system actually follow this part of <strong>the</strong> protocol? Thecloning system seems to assume that no more than two devices will be on <strong>the</strong>cable at any one time and <strong>the</strong> protocol seems to minimise <strong>the</strong> possibility ofcollisions occurring during cloning8

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