Programmable logic controller override
First Claim
1. An override board used to control an output of a programmable logic controller, the override board comprising:
- a circuit board;
electrical connections mounted to the circuit board and configured so as to allow the override board to be releasably secured from mating electrical connections disposed on the programmable logic controller;
a manual switch mounted to the circuit board;
an output device mounted to the circuit board and having an output terminal, wherein the output device is electrically connected to the manual switch, and wherein a first mode setting obtainable with the manual switch transfers control of the output terminal to the programmable logic controller, a second mode setting obtainable with the manual switch energizes the output terminal, and a third mode setting obtainable with the manual switch de-energizes the output terminal; and
a control circuit on the circuit board, the control circuit being able to receive an override clear signal other than through manipulation of the manual switch and based on the received override clear signal initiate switching of the output device to the first mode setting from at least one of the second mode setting and the third mode setting.
1 Assignment
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Accused Products
Abstract
An override board of a programmable logic controller includes a manual switch such as a push button for manual selection between a first “auto” mode where the output is controlled by the programmable logic controller, a second mode where the output is energized, and a third mode where the output is de-energized. The override board can be switched back to the “auto” mode electronically, without physically obtaining access to the controller and without moving the manual switch. The override clear signal is preferably provided on a power connection with the programmable logic controller and to a microprocessor on the override board which controls the output mode.
18 Citations
20 Claims
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1. An override board used to control an output of a programmable logic controller, the override board comprising:
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a circuit board; electrical connections mounted to the circuit board and configured so as to allow the override board to be releasably secured from mating electrical connections disposed on the programmable logic controller; a manual switch mounted to the circuit board; an output device mounted to the circuit board and having an output terminal, wherein the output device is electrically connected to the manual switch, and wherein a first mode setting obtainable with the manual switch transfers control of the output terminal to the programmable logic controller, a second mode setting obtainable with the manual switch energizes the output terminal, and a third mode setting obtainable with the manual switch de-energizes the output terminal; and a control circuit on the circuit board, the control circuit being able to receive an override clear signal other than through manipulation of the manual switch and based on the received override clear signal initiate switching of the output device to the first mode setting from at least one of the second mode setting and the third mode setting. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for controlling an output of a programmable logic controller comprising:
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releasably inserting an override board into a programmable logic controller such that the override board interfaces with a logic circuit of the programmable logic controller, the override board having an output terminal; moving a manual switch mounted to the override board, thereby changing the override board from a first mode setting in which energization of the output terminal is controlled by the programmable logic controller to at least one of a second mode setting in which the output terminal is energized and a third mode setting in which the output terminal is de-energized; and providing an override clear signal to the override board by a mechanism other than movement of the manual switch, the received override clear signal initiating switching of the output terminal to the first mode setting from at least one of the second mode setting and the third mode setting. - View Dependent Claims (15, 16, 17, 18, 19)
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20. An apparatus comprising:
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a programmable logic controller including at least one output slot; and an override board releasable secured in the output slot, used to control an output of a programmable logic controller, the override board comprising; a circuit board powered and controllable from electrical connections disposed on the programmable logic controller; a manual switch mounted to the circuit board; an output device mounted to the circuit board and having an output terminal, wherein the output device is electrically connected to the manual switch, and wherein a first mode setting obtainable with the manual switch transfers control of the output terminal to the programmable logic controller, a second mode setting obtainable with the manual switch energizes the output terminal, and a third mode setting obtainable with the manual switch de-energizes the output terminal; and a control circuit on the circuit board, the control circuit being able to receive an override clear signal other than through the manual switch and based on the received override clear signal initiate switching of the output device to the first mode setting from at least one of the second mode setting and the third mode setting.
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Specification