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US 7,098,798 B2Granted
Process device with loop override
AssigneeRosemount Inc.
InventorsGarrie Huisenga, Randy Longsdorf
Life of this patent
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Abstract
A process device for use in a process control system includes output circuitry configured to couple to a process control loop. The output circuitry controls electrical current through the loop. Loop override circuitry is configured to override operation of the output circuitry and set the electrical current in the loop to a desired level.
Claims50
A process device for use in a process control system, comprising:
- output circuitry configured to couple to a process control loop and control electrical current through the loop to transmit process-related information;
- and
- loop override circuitry, separate from the output circuitry configured to override the control of electrical current through the loop by the output circuitry and set the electrical current through the loop to a desired current level.
A method implemented in a process device of sending a desired current signal on a process control loop, comprising:
- controlling loop current in the process control loop based upon a sensed process variable with output circuitry in a device coupled to the process control loop;
- detecting an alarm condition in the process device coupled to the process control loop;
- overriding control of the loop current by the output circuitry in the device in response to a detected alarm condition;
- and
- controlling the loop current to a desired level during the step of overriding.
2 more elements
Dependencies are inferred from the claim text.