| 摘要 |
<p>Case 04-4270-U.S.-2 APPLICATION OF FELIX J. HOUVIG AND RONALD H. ROWLANDS COMMUNICATION SYSTEM AND METHOD A communication system for communicating with a process variable, e.g., pressure, transmitter over the two wires which supply power to the transmitter apparatus. The communication operation is half-duplex, bit serial transmission and is represented by the currents and voltages in the transmitter communication loop which are selectively introduced between process variable transmissions of 4-20 ma. A plurality of bit cells are provided for each data word or byte between a start bit and a parity bit cell. Following the completion of transmission of the digital data, a predetermined time period is introduced to enable the resumption of transmission of process variable data. Multiple byte transmission can also be effected between process variable transmissions by having a byte spacing less than the predetermined time period.</p> |
