| 摘要 |
<p>A status reporting system for reporting the status of a number of data points comprises a plurality of data transmitters (8) coupled to buses (6). A number of buses are coupled to a bus multiplexer (4) communicating with a processor 2. The bus multiplexer sends out interrogation signals simultaneously on all buses, and receives a response from one data transmitter on each bus. These responses are serialised and transmitted to the processor (2). The transmitters may include means (not shown in Figure 1) for changing the status of a data point in response to an interrogation signal. Some of the transmitters may be multiplexers, each coupled to a group of data points and arranged to transmit their status after having been interrogated with the group address.
<??>The transmitters may be constructed of CMOS or other low power devices, and may be provided with circuits for deriving the power to operate them from the interrogation signals.
<??>The transmitters may be addressable by trains of uniformly-spaced pulses, and may consist of a counter initially loaded with an address, a timer set to time out at the end of the pulse train, and means for initiating the transmission of a response if the counter stands at its terminal count when the timer times out. </p> |
