| 摘要 |
<p>A wired data communications network is provided including a control unit connected by cable to a series of uniquely addressable transducers for the transmission and reception of data in a polling signal. The transducers may be legacy transducers, and/or enhanced (high performance) transducers. The polling signal (figure 10) has the same structure of voltage pulses and current pulses as a conventional polling signal (figure 7), except for the addition of a high performance extension phase 1001 added at the beginning of a legacy transmission system message (figure 7). The extension 1001 allows extra information to be transmitted without affecting legacy transceiver units. Legacy transducer units decode the start voltage pulse 701a which immediately follows the high performance extension 1001, and this clears the data that was sent in the high performance extension. Each legacy transducer then responds to the legacy data frame 701 and 702 in the normal way (see figure 9). High performance transceiver units accept the high performance extension 1001 as valid data, and act upon the extension 1001, as well as the legacy transmitted data in phase 701 (see figure 11). In the same way they transmit status data in the legacy phase 702.</p> |
