System and method for accessing PLC data on demand

• US 8,738,159 B2
• Filed: 02/15/2005
• Issued: 05/27/2014
• Est. Priority Date: 03/15/2004
• Status: Expired due to Fees

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: Siemens Industry Incorporated (Siemens AG)
• Inventors: Martin, David
• Primary Examiner(s): Ali, Mohammad
• Assistant Examiner(s): Norton, Jennifer L
• Application Number:
  US11/058,532
• Publication Number:
  US 20050203648A1
• Time in Patent Office: 3,388 Days
• Field of Search: 700/9, 700/17, 700/83, 700/86, 700/87, 709/208, 709/211, 709/225, 709/238, 719/330, 719/331
• US Class Current: 700/87
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05B 19/05 Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
• CPC Class Codes: G05B 19/052 Linking several PLC's
• CPC Class Codes: G05B 19/056 Programming the PLC
• CPC Class Codes: G05B 19/408 characterised by data handling or data format, e.g. reading, buffering or conversion of data
• CPC Class Codes: G05B 19/409 characterised by using manual data input [MDI] or by using control panel, e.g. controlling functions with the panel; characterised by control panel details or by setting parameters G05B19/408, G05B19/4093 take precedence
• CPC Class Codes: G05B 2219/1205 Memory access for different processors, memory arbitration, mailbox
• CPC Class Codes: G05B 2219/1208 Communication, exchange of control, I-O data between different plc,
• CPC Class Codes: G05B 2219/2222 Use of priority levels for gaining access to resources
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 16/284 Relational databases
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/78 to assure secure storage of data address-based protection against unauthorised use of memory G06F12/14; record carriers for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: G06F 9/547 Remote procedure calls [RPC]; Web services
• CPC Class Codes: H04L 63/083 using passwords cryptographic mechanisms or cryptographic arrangements for entity authentication using a predetermined code H04L9/3226
• CPC Class Codes: H04L 9/3226 using a predetermined code, e.g. password, passphrase or PIN network architectures or network communication protocols for supporting authentication of entities using passwords in a packet data network H04L63/083
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99937 Sorting

Abstract

A system for providing programmable logic data on demand includes a portion for receiving a plurality of data requests at the programmable logic controller and a portion for processing the plurality of data requests asynchronously. An interface enables asynchronous processing to enhance and extend capabilities of the programmable logic controller.

Claims

1. A method for providing programmable logic controller data on demand, the method comprising:

providing a programmable logic controller (PLC) having an internal memory and an external interface, wherein the external interface is implemented as a dynamic linked library (DLL) that provides direct memory access (DMA) transfers to and from the internal memory of the PLC;

providing an external end user application executing on a processor external to the PLC, the application including an executable access code and a function call and operative to send the access code and the function call to the external interface of the PLC;

receiving the access code and function call at the external interface of the PLC;

responding to the access code by granting to the end user application by the PLC, access to the internal memory of the PLC,

wherein, once the access code is received, the processor external to the PLC is operable to directly read from or write to, via asynchronous DMA transfers, the internal memory of the PLC with involvement of the PLC limited to executing the DLL.

2. The method of claim 1, wherein the function call is one of a read call, a write call, a cyclic data request, or combinations thereof.

3. The method of claim 2, further including:

receiving a call to create the cyclic data request; and

processing the cyclic data request.

4. The method of claim 2, further including:

receiving a call to terminate processing of the cyclic data request; and

terminating the processing.

5. The method of claim 2, further including receiving a call to delete a cyclic read of the memory.

6. The method of claim 1, further including returning data stored in the memory to the external application in response to the function call.

7. A system for providing programmable logic controller data on demand, the system comprising:

a programmable logic controller (PLC) having an internal memory and an external interface, wherein the external interface is implemented as a dynamic linked library (DLL) that provides direct memory access (DMA) transfers to and from the internal memory of the PLC; and

an external end user application executing on a processor external to the PLC, the application including an executable access code and a function call, wherein the application is operative to send the access code and the function call to the external interface of the PLC,

wherein the external interface of the PLC is operative to receive the access code and the function call from the end user application and to respond to the access code by granting to the end user application access to the internal memory of the PLC,

wherein, once the access code is received, the processor external to the PLC is operable to directly read from or write to, via asynchronous DMA transfers, the internal memory of the PLC with involvement of the PLC limited to executing the DLL.

8. The system of claim 7 wherein the function call is one of a read call, a write call, a cyclic data request or combinations thereof.

9. The system of claim 8, wherein the external interface is operative to receive a call to create a cyclic data request and to process the cyclic data request.

10. The system of claim 8 wherein the external interface is operative to receive a call to terminate processing of a cyclic data request and to terminate the processing.

11. The system of claim 8 wherein the external interface is operative to receive a call to delete a cyclic read of the internal memory.

12. The system of claim 7 wherein the external interface is operative to return data stored in the internal memory to the external application in response to the function call.

13. A system for providing programmable logic controller data on demand, the system comprising:

a programmable logic controller (PLC) having an internal memory and an external interface, wherein the external interface is operative to enable direct memory access (DMA) transfers to and from the internal memory of the PLC;

an external application executing on a processor external to the PLC, the application including an executable access code and a function call, wherein the application includes instructions that when executed on the processor are operative to transmit the access code and the function call to the external interface of the PLC;

wherein the external interface includes executable instructions that when executed by the external interface are operative to;

receive the access code and the function call at the external interface of the PLC;

grant the external application access to the internal memory of the PLC in response to receiving the access code from the external application,

wherein, once the access code is received, the processor external to the PLC is operable to directly read from or write to, via asynchronous DMA transfers, the internal memory of the PLC with involvement of the PLC limited to executing the external interface.

14. The system of claim 13 wherein the function call is one of a read call, a write call, a cyclic data request or combinations thereof.

15. The system of claim 14, wherein the external interface is operative to receive a call to create a cyclic data request and to process the cyclic data request.

16. The system of claim 14 wherein the external interface is operative to receive a call to terminate processing of a cyclic data request and to terminate the processing.

17. The system of claim 14 wherein the external interface is operative to receive a call to delete a cyclic read of the internal memory.

18. The system of claim 13 wherein the external interface is operative to return data stored in the internal memory to the external application in response to the function call.