System and method for providing an application with memory access methods
View Patent ↗A system for providing an application with a plurality of methods for accessing memory of a programmable logic controller includes an application, an interface for establishing communication between the application and a programmable logic controller, and a shared memory area initiated by the application or the programmable logic controller. The shared memory area includes an input memory and an output memory. The application is enabled by the interface to write to the input memory and to read from the output memory.
1. A system comprising:
an interface means for establishing communication between an application and an control program of a programmable logic controller; and
a shared memory area initiated by the application or the control program of the programmable logic controller, the shared memory area including an input memory and an output memory, the application enabled by the interface means to write input data only to the input memory and to read output data only from the output memory without directly communicating the input data or the output data through the control program.
2. The system as defined in claim 1 , wherein the application is disposed remotely from the programmable logic controller.
3. The system as defined in claim 1 , further including a control program in the programmable logic controller for reading from the input memory and writing to the output memory.
4. The system as defined in claim 1 , wherein the application is configured to access the input and output memories separately from the programmable logic controller.
5. The system as defined in claim 1 , wherein the shared memory area is a port random access memory area.
6. The system as defined in claim 5 , wherein each of the input memory and the output memory are four thousand bytes.
7. The system as defined in claim 1 , further comprising at least one additional application, each additional application having respective interface means for accessing the shared memory area.
8. A method comprising the steps of:
instantiating a peripheral input memory and a peripheral output memory in a shared memory area between a control program of a programmable logic controller and an application;
establishing communication between the programmable logic controller and the application for a data exchange in the shared memory area;
reading unprocessed data only from the peripheral input memory without directly communicating the unprocessed data through the control program;
processing the unprocessed data; and
writing processed data only to the peripheral output memory without directly communicating the processed data through the control program.
9. The method as defined in claim 8 , wherein the peripheral input memory and the peripheral output memory are input and output memory of the programmable logic controller.
10. The method as defined in claim 8 , wherein the shared memory area is established by the programmable logic controller when triggered by the application.
11. The method as defined in claim 8 , further comprising the steps of:
requesting a connection by the application to the programmable logic controller, and wherein if successful, receiving a handle to the programmable logic controller for use when reading and writing data to specify the programmable logic controller in communication with the application; and
reading or writing data by the application.
12. The method as defined in claim 11 , further comprising the steps of:
reading additional data by the application from the peripheral output memory provided by the programmable logic controller;
processing the additional data; and
writing the processed additional data by the application to the peripheral input memory.
13. The method as defined in claim 8 , wherein the steps of reading and writing are defined by data types supported by the programmable logic controller.
14. The method as defined in claim 8 , further comprising the step of requesting a connection by the application to the programmable logic controller, and wherein if unsuccessful, requesting a connection again for a predetermined period of time.
15. The method as defined in claim 8 , further comprising the steps of:
establishing communication between an additional application and the shared memory area;
requesting one or more additional connections by the additional application to the programmable logic controller, and wherein if successful, receiving an additional handle to the programmable logic controller for use when reading and writing data to specify which programmable logic controller the additional application is reading and writing data from; and
accessing data by the additional application.
16. The method as defined in claim 8 , wherein the shared memory area includes a dual port random access memory.
17. A system comprising:
an application separate from a programmable logic controller;
interface means for establishing communication between the application and a control program of the programmable logic controller; and
a shared memory area implemented by the control program of the programmable logic controller triggered by an input from the application, the shared memory area including an input memory and an output memory, the application enabled by the interface means to write input data only to the input memory and to read output data only from the output memory without directly communicating the input data or the output data through the control program.
18. The system as defined in claim 17 , wherein the application is configured to access the input and output memories separately from the control program of the programmable logic controller.
19. The system as defined in claim 17 , wherein the application and the programmable logic controller communicate via a handle, the handle specifying to the application which programmable logic controller the application is reading and writing data.
20. The system as defined in claim 19 , wherein the data is a data type supported by the programmable logic controller.