US 4,021,783 A · Programmable controller

Abstract

A programmable system controller stores in memory a sequence of program words directly simulating a planar ladder diagram characterizing the desired operation of a controlled system. The ladder diagram is a set of n rung-by-m column arrays of contacts interconnected with particular controlled devices of the system. The program words are read out of the memory in a sequence to directly represent the ladder diagram on a rung-by-rung basis for each column. The controller includes an interface unit coupled to a set of input switches for providing switch signals that are indicative of the operating status of the machine. A data processing unit is provided with an accumulator having a plurality of at least n storage units respectively corresponding to each rung of the ladder diagram. In response to the program words and to the switch signals, the accumulator sequentially determines the states of the storage units according to whether the switch signals are indicative that a particular rung of one column of the ladder diagram can contribute towards operating the controlled device as it is connected in the ladder diagram. After the plurality of storage units have been conditioned according to the rungs in one column, the next column of the ladder diagram is considered for conditioning the storage units. After all columns of the ladder diagram have been considered, a preselected one of the plurality of storage units contains an output signal indicative of whether the controlled device should be operated. A more specific feature of the controller is the interface circuit which alternately provides asynchronous or synchronous input of the switch signals using a partitioned random access memory as a novel buffer register.

Claims41

Dependent claims

A sequence controller for selectively operating at least one controlled device in a controlled system in response to the operating status of a set of switches in the system, the switches being operated in response to operation of the system, and the operation of the system being characterized by a ladder diagram which represents a connection, in an n rung-by m column array, of the controlled device with a plurality of binary elements corresponding to said switches, comprising:

(a) a system interface responsive to the switches for deriving switch signals having values which are indicative of the operating status of each of the switches;
(b) program storage means responsive to a set of timing signals for storing and providing a sequence of program words which represents said connection of binary elements and controlled device in said ladder diagram, said sequence of program words thereby characterizing the desired operation of the controlled device;
(c) data processing means for producing an output signal in response to the sequence of program words and to the switch signals for effecting operation of the selected controlled device, the data processing means including:
(i) an accumulator having a plurality of at least n storage units individually conditionable in response to a set of processor signals, said storage units being effective to provide said output signal,
(ii) process signal generating means responsive to the sequence of program words and to the switch signals for generating the set of processor signals and the set of timing signals, the processor signals representative of whether the values of the switch signals are indicative that the corresponding binary elements in the planar array would contribute towards operating said controlled device;
and
(iii) timing means responsive to said set of timing signals for selecting the storage unit of said accumulator to be conditioned by said processor signals, whereby the selected storage unit after having been conditioned by the processor signals is indicative whether the binary element corresponding to said storage unit would contribute, as determined by the value of the corresponding switch signals, towards operating the controlled device.

4 more elements

(a) input means responsive to the switches for deriving switch signals having values which are indicative of the operating status of each of the switches;
(b) program storage means responsive to a set of timing signals for storing and providing a sequence of program words which represents said connection of binary elements and controlled device in said ladder diagram, said sequence of program words thereby characterizing the desired operation of the controlled device on a rung by rung basis for each of the m columns;
(c) an accumulator having a plurality of at least n storage units which are individually conditionable in response to a set of switch conditioned signals and to a set of array conditioned signals and which respectively correspond to a rung in the planar array, the accumulator being responsive to the program words for producing an output signal which operates the controlled devices as a function of the values stored by the individual storage units;
(d) process signal generating means for producing the timing signals, for producing the switch conditioned signals, in response to the program words and to the switch signals, and for producing the array conditioned signals in response to the program words;
(e) timing means responsive to said set of timing signals for selecting the storage unit, corresponding to the rung represented by a given program word, to be conditioned by said switch conditioned signals, whereby the selected storage unit after having been so conditioned is indicative whether said rung would contribute towards operating said controlled device;
(f) logic circuitry responsive to the program words for reconditioning the values of storage units in the accumulator according to the values of other storage units;
and
(g) output means coupled to the accumulator for providing the output signal to the controlled system, the value of one storage unit determining whether the controlled device should be operated.

5 more elements

A sequence controller for selectively operating at least one controlled device in a controlled system in response to operating status of a set of switches in the system, the switches being operated in response to operation of the system, and the operation of the system being characterized by a ladder diagram which represents a connection, in an n rung-by m column array, of the controlled device with a plurality of binary elements corresponding to said switches, comprising:

(a) input means responsive to the switches for deriving switch signals having values which are indicative of the operating status of each of the switches;
(b) program storage responsive to a set of timing signals for storing and providing a sequence of program words representing the planar ladder diagram, said sequence including input words having bits representing the type of each binary element and the location of the associated switch, process words having bits representing the interconnection of the binary elements, and output words having bits representing the interconnection of the selected controlled device with the binary elements, the sequence of program words thereby characterizing the ladder diagram on a rung by rung basis for each of the m columns;
(c) an accumulator having a plurality of storage units for providing an output signal as a function of the values of the storage units, the storage units being individually conditionable in response to a set of processor signals to thereby provide the output signal indicative of whether the states of the binary elements would effect operation of the selected controlled device as it is connected in the ladder diagram;
(d) process signal generating means responsive to the sequence of program words and to the switch signals for generating the set of processor signals and the set of timing signals, the processor signals representative of whether the values of the switch signals are indicative that the corresponding binary elements in the planar array would contribute towards operating said controlled device;
(e) timing means responsive to said set of timing signals for selecting the storage unit of said accumulator to be conditioned by said processor signals, the selected storage unit corresponding to the rung of the ladder diagram then represented by said program words, whereby the selected storage unit having having been conditioned by the processor signals is indicative whether the binary element corresponding to said storage unit would contribute, as determined by the value of the corresponding switch signals, towards operating the controlled device;
(f) output means for selectively coupling the output signal to the machine for operating the controlled device.

3 more elements

A method of sequentially operating a controlled device in a system in accordance with the conditions of a plurality of switches in the system, the switches being operated by operation of the system, wherein a planar ladder diagram is provided in which a plurality of binary elements, each associated with a respective one of the switches, are interconnected with the controlled device, said binary elements each being represented in a normal state and arranged in a plurality of rows in the diagram with individual binary elements of the rows arranged in respective columns of the diagram and said controlled device being disposed in one of said rows by itself in an end column of the diagram, and wherein there are a plurality of individually conditionable storage units corresponding in number to the number of rows of said diagram, comprising:

(a) storing in memory and producing therefrom a sequence of program words which directly represent the individual binary elements, their normal states, and the controlled device, wherein the program words are arranged to characterize the interconnection in a row-by-row sequence proceeding column by column to said end column;
(b) producing a series of switch status signals indicative of the actual status of said switches;
(c) conditioning successive storage units in response to said sequence of program words and in response to said switch status signals, the conditioned storage units thereby indicating whether the binary elements in successive rows of each column would contribute as determined by the value of the switch status signals corresponding to the respective binary elements, to operation of said controlled device as connected in said ladder diagram;
(d) detecting the condition of the storage unit corresponding to the row in which said controlled device is disposed in said end column;
and
e. producing an output signal for operating said controlled device in accordance with the condition of said storage unit corresponding to the row and column of said controlled device.

3 more elements

A method of sequentially controlling operation of a controlled device in a controlled system in response to operating status of switches in the controlled system, the switches being operated in response to operation of the system, wherein there are a plurality of individually conditionable storage units and a ladder diagram which defines an interconnection in rungs and columns of the controlled device with binary elements, each binary element associated with one of the switches, the ladder diagram selected to characterize operation of the controlled device according to the states of the binary elements, comprising the steps of:

(a) generating a sequence of program words representing the planar ladder diagram in a rung by rung sequence for successive columns;
(b) sensing the operating status of the switches corresponding to the binary elements and providing a plurality of switch signals indicative of said operating status;
(c) generating in response to the program words and to the switch signals a plurality of processor control signals indicative of whether the switches corresponding to the binary elements in respective rungs of a given column are in a logic state which would effect operation of the controlled device as determined by the ladder diagram;
(d) associating respective ones of the plurality of storage units with corresponding rungs of the ladder diagram;
(e) selectively conditioning the plurality of individually programmable storage units in response to the process control signals;
and,
(f) logically combining the values of the storage units to provide an output signal for selectively operating the controlled device.

4 more elements

In a sequence controller for selectively operating a controlled device in a controlled system in response to the operating status of a set of switches in the controlled system, the switches being operated by operation of the system, the controller having system interface means for coupling to the switches and deriving switch signals indicative of the operating status of the switches, program storage means for storing and providing a sequence of program words representing states of selected switches during each of a series of scan cycles, and processing means responsive to the switch signals and to the program words for producing an output signal which controls operation of the controlled device, the improvement wherein the system interface means comprises:

(a) storage means having a plurality of addressable storage locations which are effectively partitioned into at least first and second groups of locations for storing values of the switch signals;
and
(b) control means for selectively writing the values of the switch signals into one group of locations during a first scan cycle, writing into a second group during a next-in-series second scan cycle, and for reading the values of the switch signals out of the one group during the next-in-series second scan cycle.

Dependencies are inferred from the claim text.

Programmable controller

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Programmable controller

Life of this patent

Abstract

Claims41