초록 ▼

A process transmitter communications circuit has link terminals which are coupled to a process link, which supplies power to the circuit. A power source is coupled to one of the link terminals and is independent from the power supplied from the process link. Communications circuitry is coupled to th

A process transmitter communications circuit has link terminals which are coupled to a process link, which supplies power to the circuit. A power source is coupled to one of the link terminals and is independent from the power supplied from the process link. Communications circuitry is coupled to the power source and link terminals, which transmits a transmitter signal over the process link, through the link terminals. A power sensing component is coupled to at least one of the link terminals and the communications circuitry and senses whether the power supplied by the process link is inadequate to transmit the transmitter signal. A power control component is coupled to the power source, the link terminals and the communications circuitry and selectively applies power from the power source to the communications circuitry for transmitting the transmitter signal when the power sensing component senses there is inadequate power supplied by the process link.

대표청구항 ▼

[ What is claimed is:] [1.] A process transmitter communications circuit for coupling to a process link which supplies power to the circuit, the circuit comprising:link terminals which are adapted to couple to the process link;a power source coupled to at least one one of the link terminals and inde

[ What is claimed is:] [1.] A process transmitter communications circuit for coupling to a process link which supplies power to the circuit, the circuit comprising:link terminals which are adapted to couple to the process link;a power source coupled to at least one one of the link terminals and independent from the power supplied from the process link;communications circuitry coupled to the power source and link terminals, which is adapted to transmit an analog process signal and a digital transmitter signal over the process link, through the link terminals, wherein analog process signal has an analog level which is controlled by the communications circuitry based on a process variable;a power sensing component coupled to at least one of the link terminals and the communications circuitry, which is adapted to sense whether the power supplied by the process link is inadequate to transmit the transmitter signal; anda power control component coupled to the power source, the link terminals and the communications circuitry which is adapted to selectively apply power from the power source to the communications circuitry, the communications circuitry being adapted to transmit the digital transmitter signal, but not the analog process signal, with the power supplied by the power source when the power sensing component senses there is inadequate power supplied by the process link.