Method and circuitry for a programmable controller system
First Claim
1. In an input/output (I/O) system of a programmable controller, a communications method and I/O circuit for exchanging information on control and operating parameters between a controlling element of the I/O system and a controlled element thereof which includes an output control device activated and deactivated in accordance with the control information, comprising the steps of:
- a) generating in the controlling element a control signal in the form of sequential pulse frames, each frame having at least one control pulse defining said control information;
b) transmitting said control signal to said controlled element and generating in the controlled element a clock pulse for each control pulse such that said clock pulse follows said control pulse by a pre-selected time interval on each frame, there being one clock pulse for each control pulse such that there is a fixed time relationship between each control pulse and each clock pulse;
c) generating in the controlled element a diagnostic signal independent of the control signal but which is indicative of operating parameters of the controlled element; and
d) using said clock pulse on each frame to cause a sampling of said control information and to cause a transmission of a value of said diagnostic signal to said controlling element;
wherein the I/O circuit comprises a switch processor, a plurality of signal conditioning circuits, and a switch section.
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Abstract
The invention disclosed is useful in an I/O system of a programmable controller and provides a method and circuitry by which control and diagnostic information is exchanged between a control unit of an I/O module and a plurality of input/output points of the I/O module. A control signal is generated in the control unit in the form of sequential pulse frames such that the control information is defined by a series of pulse width modulated pulses. Each frame includes a no-pulse time period following the review of pulses to mark the end of a frame. Each I/O point receives a control signal of its own and generates a clock pulse in response to each pulse. The clock pulse initiates a sampling of the corresponding pulse and simultaneously initiates return of a diagnostic signal value to the central unit by implementation of firmware in a switch processor. Thus, the control signal provides for sampling of its own content and provides for a return of a diagnostic data bit for each control bit.
27 Citations
27 Claims
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1. In an input/output (I/O) system of a programmable controller, a communications method and I/O circuit for exchanging information on control and operating parameters between a controlling element of the I/O system and a controlled element thereof which includes an output control device activated and deactivated in accordance with the control information, comprising the steps of:
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a) generating in the controlling element a control signal in the form of sequential pulse frames, each frame having at least one control pulse defining said control information;
b) transmitting said control signal to said controlled element and generating in the controlled element a clock pulse for each control pulse such that said clock pulse follows said control pulse by a pre-selected time interval on each frame, there being one clock pulse for each control pulse such that there is a fixed time relationship between each control pulse and each clock pulse;
c) generating in the controlled element a diagnostic signal independent of the control signal but which is indicative of operating parameters of the controlled element; and
d) using said clock pulse on each frame to cause a sampling of said control information and to cause a transmission of a value of said diagnostic signal to said controlling element;
wherein the I/O circuit comprises a switch processor, a plurality of signal conditioning circuits, and a switch section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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- 11. An input/output (I/O) circuit comprising a switch processor, a plurality of signal conditioning circuits, and a switch, wherein the switch processor comprises firmware programmed to accept signals from the signal conditioning circuits and a microcontroller as data inputs, and to act upon the information contained in those inputs to control the switch and provide diagnostic information to the microcontroller.
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20. In an input/output (I/O) system of a programmable controller, an input/output mode comprising:
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an operations control unit including a switch processor for providing a control signal in the form of sequential pulse frames, each frame having at least one control pulse defining a desired control status; and
at least one I/O point connected to the operations control unit and having an output control device subject to activation and deactivation as an operative condition in accordance with said control status and further including;
(1) timing means responsive to each control pulse to generate a clock pulse which follows said control pulse by a pre-selected time interval on each frame, there being one clock pulse for each control pulse such that there if a fixed time relationship between such pulses;
(2) firmware located on the switch processor and connected to the I/O point for providing a diagnostic signal having a value indicative of the operative condition of the I/O point;
(3) means connected to receive each clock pulse and responsive to each clock pulse on each frame to cause a sampling of each control pulse to determine the desired control status; and
(4) means connected to receive each clock pulse and the diagnostic signal and responsive to said clock pulse on each frame to cause a transmission of a value of said diagnostic signal to the operations control unit. - View Dependent Claims (21, 22)
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23. In a programmable controller input/output system of the type having a plurality of input/output modules, each adapted to be located in proximity to a process being controlled, circuitry for use in such modules, comprising:
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output control means responsive to be activated and deactivated by a command signal;
an operations controller generating at least one control signal in the form of sequential pulse frames, each frame of which contains at least one pulse defining a control status for the output control means and a time interval without pulses defining the end of the frame whenever said interval reaches a first pre-selected time duration;
a communications and control section receiving said control signal and including firmware responsive to said at least one pulse to provide said command signal for activating and deactivating said output control means in accordance with said control status for each frame and means responsive to said time interval for synchronizing operation of said communications and control section with each frame;
sensing means providing status signals indicative of the operative condition of said output control means; and
wherein said communications and control section includes a switch processor with on-board firmware coding for receiving said status signals and responsive thereto to produce a diagnostic signal which is updated on each frame of said control signal and first selector means for transmitting said diagnostic signal to said operations controller on each frame of said control signal. - View Dependent Claims (24, 25, 26, 27)
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Specification