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US 10,558,202 B2Granted
Signal transmission circuit, field device, and plant control system
AssigneeYokogawa Electric Corporation
InventorsTatsuro Endo, Masami Wada
Life of this patent
Estimating the term…
Abstract
A signal transmission circuit includes a first photocoupler to which a transmission signal is input, an edge detection circuit which is disposed in a primary side of the first photocoupler, the edge detection circuit being configured to detect a rising edge and a falling edge of the transmission signal, and an edge demodulation circuit which is disposed in a secondary side of the first photocoupler, the demodulation circuit being configured to demodulate the transmission signal by using only one of the rising edge and the falling edge of an edge detection signal output from the edge detection circuit via the first photocoupler.
Claims18
A signal transmission circuit comprising:
- a first photocoupler to which a transmission signal is input;
- an edge detection circuit which is disposed in a primary side of the first photocoupler, the edge detection circuit being configured to detect a rising edge and a falling edge of the transmission signal;
- an edge demodulation circuit which is disposed in a secondary side of the first photocoupler, the edge demodulation circuit being configured to demodulate the transmission signal by using only one of the rising edge and the falling edge of an edge detection signal output from the edge detection circuit via the first photocoupler;
- a second photocoupler to which an enable signal is input;
- and
- an output control circuit configured to control an output of the signal demodulated by the edge demodulation circuit based on the enable signal transmitted via the second photocoupler.
3 more elements
A field device comprising:
- a calculation circuit configured to calculate a process value indicating a state quantity of a measurement target;
- and
- a signal transmission circuit configured to transmit a transmission signal indicating the process value calculated by the calculation circuit,
- wherein the signal transmission circuit comprises:
- a first photocoupler to which the transmission signal is input from the calculation circuit;
- an edge detection circuit which is disposed in a primary side of the first photocoupler, the edge detection circuit being configured to detect a rising edge and a falling edge of a signal to be transmitted;
- an edge demodulation circuit which is disposed in a secondary side of the first photocoupler, the edge demodulation circuit being configured to demodulate the signal to be transmitted by using only one of the rising edge and the falling edge of an edge detection signal output from the edge detection circuit via the first photocoupler;
- a second photocoupler to which an enable signal is input;
- and
- an output control circuit configured to control an output of the signal demodulated by the edge demodulation circuit based on the enable signal transmitted via the second photocoupler.
7 more elements
A plant control system comprising:
- a field device which is installed in a plant;
- and
- a controller which is communicably connected to the field device, the controller being configured to control the field device,
- wherein the field device comprises:
- a calculation circuit configured to calculate a process value indicating a state quantity of a measurement target;
- and
- a signal transmission circuit configured to transmit a transmission signal indicating the process value calculated by the calculation circuit,
- wherein the signal transmission circuit comprises:
- a first photocoupler to which the transmission signal is input from the calculation circuit;
- an edge detection circuit which is disposed in a primary side of the first photocoupler, the edge detection circuit being configured to detect a rising edge and a falling edge of a signal to be transmitted;
- an edge demodulation circuit which is disposed in a secondary side of the first photocoupler, the edge demodulation circuit being configured to demodulate the signal to be transmitted by using only one of the rising edge and the falling edge of an edge detection signal output from the edge detection circuit via the first photocoupler;
- a second photocoupler to which an enable signal is input;
- and
- an output control circuit configured to control an output of the signal demodulated by the edge demodulation circuit based on the enable signal transmitted via the second photocoupler.
11 more elements
Dependencies are inferred from the claim text.