Contact histogram for programmable controller
AssigneeAllan-Bradley Company
InventorsValdis Grants, Odo J. Struger
Life of this patent
Estimating the term…
Abstract
A controller programmer connects to a programmable controller and serves as a means for loading and editing the control program. When the contact histogram mode of operation is employed the logic state of a selected I/O device connected to the controller is monitored, and each time its status changes, its present status is recorded along with the time interval between status changes. A first embodiment is described in which the invention is employed in a hardwired controller program loader and a second embodiment is described in which the controller program loader employs a programmed microprocessor. In the first embodiment the status changes are recorded on paper tape and in the second embodiment they are recorded on a cathode ray tube screen.
Claims12
In a controller having a processor which operates in response to control program instructions stored in a controller memory to periodically examine the status of a plurality of input devices on a machine to be controlled, the improvement therein of a contact histogram which provides a visual record of the status of a selected one of said input devices and which comprises:
- means for storing the I/O address of a selected input device to be monitored;
- means connected to said storing means and said controller for comparing said stored I/O address with an I/O address in each program instruction executed by said controller, said comparing means generating a selected logic signal when they are identical;
- means connected to said controller and said comparing means for storing a signal indicative of the status of said selected input device when said selected logic signal is generated by said comparing means;
- timer means for accumulating elapsed time between status changes of said selected input device and recording the same when enabled;
- and
- means connected to said status storing means for enabling said timer means when the stored status of said selected input device changes status.
In a programmable controller having a processor which operates in response to control program instructions stored in a controller memory to periodically examine the status of a plurality of input devices on a machine to be controlled, the improvement therein of a contact histogram which provides a visual record of the status of a selected one of said input devices and which comprises:
- means connected to said controller for periodically examining the status of a selected input device to be monitored;
- means for storing the status of an examined input device;
- means for accumulating elapsed time between changes in status of said selected input device and recording the same when enabled;
- and
- means connected to said status storing means for enabling said recording means when the stored status of said selected input device changes status.
In a programmable controller having a processor which operates in response to control program instructions stored in a controller memory to periodically examine the status of a plurality of input devices on a machine to be controlled, the improvement therein of a contact histogram which provides a visual record of the status of a selected one of said input devices and which comrises:
- means coupled to said processor for manually selecting the input device;
- means coupled to said processor for storing the status of the selected input device;
- means coupled to said status storing means for detecting a change in the status of said selected input device from one state to another;
- timer means coupled to said detecting means and being operable in response to a detected change in the status of said selected input device to commence accumulating elapsed time from the status change event;
- and
- recording means coupled to said timer means and being operable to visually display the elapsed time between status change events.
Dependencies are inferred from the claim text.