FIELD OF INVENTION

The present invention relates an interface element between Level – 1 tier equipment to Level – III tier equipment. More particularly the present invention discloses automation of equipment’s / system through an interface element configured for data access and communication between two isolated domains of automation using Object Linking & Embedding for Process Control (OPC).

BACKGROUND ART

Conventional, control systems commonly employ one or more industrial controllers. A typical industrial controller is a special purpose processing device for controlling (e.g., via an automated and a semi-automated means) industrial processes, machines, manufacturing equipment, plants, and the like. Such controllers can execute a control program or routine in order to measure one or more process variables or inputs representative of a status of a controlled process and/or effectuate outputs associated with control of the process. For example, an output module can interface directly with a controlled process by providing an output from memory to an actuator such as a motor, drive, valve, solenoid, and the like. In distributed control systems, controller hardware configuration can be facilitated by separating the industrial controller into a number of control elements, each of which can perform a different function. Particular control modules needed for the control task can be connected together on a common backplane within a rack and/or through a network or other communications medium. Various control modules can also be spatially distributed along a common communication link in several locations. Data can be communicated with these remote modules over a common communication link, or network, wherein any or all modules on the network communicate via a common and/or an industrial communications protocol. Controllers within a control system can communicate with each other, with controllers residing in other control systems and/or with systems and/or applications outside of a control environment (e.g., business related systems and applications).
Nonetheless, information management such as message exchange using different protocols and configurations is becoming complex. For example, the mapping of information from production management to process control and custom glue code for integrating systems with different protocols and formats make configuration and management a difficult task. Moreover, failed communications (e.g., messages that are not received or acted upon), delayed responses (e.g., as a function of the time difference between a sent message and a re-send), and additional overhead (e.g., consumption of processing cycles to review stored notifications, schedule re-transmissions and re-send messages) further add to the problems involved.

One way to resolve the aforesaid issue was to procure gateway hardware from PLC manufacturer. The proprietary hardware in the PLC network will fetch required process data from the PLC processor and transmit the same in ERP network using TCP/IP protocol. A dedicated software in ERP module can receive the PLC data from the network and store it in suitable database.

Drawbacks

The main drawback of the aforesaid gateway hardware is its proprietary nature and dependence on specific PLC manufacturer. Due to this, such hardware systems are generally very expensive. In case of any change in Level-I PLC system, the hardware needs to be replaced. Similarly the hardware needs to up-graded in case of any change in PLC hardware / software version. However, the greatest drawback is proprietary availability of such systems. Hence a open system is required which is independent of make, model and version of PLC hardware / software.

SUMMARY OF INVENTION

The subject invention concerns systems for interfacing Level-I automation system like PLC with ERP (Level-III) in an industry using concepts of OLE for Process Control (OPC) to facilitate communication, interaction, and connectivity between industrial automation devices or systems and data supply systems or services.

In accordance with an aspect of the invention, an interface is disclosed including a device and a data interface component. The device interface receives commands, statements or other units of data or database interaction, from an ERP device such as an industrial controller and transmits the received statements to the data interface component. The data interface component subsequently transmits the statements to a database server system for execution or evaluation and obtains a response. The response is then transmitted back to the data interface component, the device interface component, and ultimately to the ERP device providing the statements.

In accordance with another aspect of the invention, the device interface component can obtain statements, commands, expressions in the form of protocol strings, from one or more automation devices and transmit them to the data interface component.

According to other aspects of the invention, the provided interface system can reside and execute as middleware, on a controller or other automation device, or on a database server.

In accordance with still another aspect of the invention, methods are disclosed to facilitate communication with a database. The statements or commands are received from an ERP device and transmitted to a database system or service for execution or evaluation.

Therefore such as herein described there is provided a system for interfacing Level-I system with Level-III system in an industry for automation comprising of a PC platform; a Level I, PLC based control system envisaged through a Control Logix processor; a Lever III, ERP relational database; a bidirectional data communication HMI network through an OPC server and (OLE for Process Control) client module configured for :- initiating DCOM (Distributed Component Object Model) / COM (component object model) and creating an local instance of server; creating a dedicated group for establishing connection with specified Level I system from Level III system through a client module; and accessing and integrating the process data as asynchronous contact interface wherein the data is read periodically at an interval of a 2 sec.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

Fig. 1 illustrates a Block Schematic of developed System in accordance with the present invention;
Fig. 2 illustrates a Flow Chart of Developed System in accordance with the present invention;
Fig. 3 illustrates the System Architecture in accordance with the present invention.
DETAILED DESCRIPTION:

ERP is widely used in steel industry as Level-III tier of automation. It needs huge process related data from various units of Steel Plant. However, these process data are generally available Level-I equipment’s of Automation like PLC, DCS, loop controllers etc. These level-I assortments are generally proprietary in nature and does not communicate with each other as well as does not support direct data access. Hence data access from these systems is very difficult. A novel system has been developed for a similar case, where a Level-I Programmable Automation Controller (PAC) of Rockwell Automation make at Sinter Machine #2 of Bokaro Steel Plant has been interfaced with plant’s ERP system using Object Linking & Embedding for Process Control (OPC). A computer client module has been developed using Microsoft Foundation Class (VC++) dovetailing PAC server. The server is directly connected with PAC’s, HMI (Human Machine Interface) Ethernet network enabling data access. The client module in a computer connected with same network, fetches the PAC data right from the server using concepts of OPC and COM/DCOM. The data is periodically written in a separate computer database in ERP as well as it is made available through CSV text file. ERP systems then directly access these data from database as well as CSV text file.

The developed innovation is under operation at Machine # 2 of Sinter Plant of Bokaro Steel Plant. The complicated sintering process of Machine #2 is being controlled by a Programmable Logic Controller (PLC), which comprise of Level – I tier of automation. Accordingly all the process related critical data are available in the PLC processor and HMI. However, the same is localized in the proprietary data network of PLC restricted in the control room of sinter Machine #2.

Bokaro Steel Plant has a plant wide network of ERP as Level-III tier of automation. For effective monitoring, planning, scheduling and analysis, of Sinter Plant (Machine #2) data, it was felt essential that critical process parameters to be made available in the ERP system. However, both PLC (Level- I) as well as ERP (Level-III) framework operates under different proprietary architectures in terms of hardware, networking, operating system and programming language and there is no direct means of interfacing these two distinct and different assortments of automation. A block schematic of developed system is shown in Fig 1.

In view of above, a novel system has been developed to dovetail data from proprietary PLC framework to ERP system without using any additional system hardware.

As discussed above, a need was felt to integrate PLC system (Make: Rockwell Automation, Model: Control Logix) of Sinter Machine # 2 of Bokaro Steel Plant to plant wide ERP network. The present innovation is based on OPC (Object Linking & Embedding for Process Control). OPC is an open protocol based on concepts of COM / DCOM.

OPC is an open interface for integrating different automation devices. OPC facilitates inter application linkage for data access, historical trends and alarm / event etc. It is based on COM / DCOM base-interface ‘I Unknown’, which by virtue of its inheritance characteristic permits read / writes data access between two applications written using different languages, developed under different platforms, under different operating systems and versions. OPC follows a hierarchical architecture, where Level – I system serves as Server. The flow chart of developed client system is depicted in Fig. 2.

The PLC (level I) and ERP (Level III) interface is based on client server architecture. Where Level I PLC facilitates the server component and ERP (Level III) renders the client. In this particular application of Sinter Plant Machine #2 at Bokaro Steel, Rockwell Automation PLC acts as Server with its Server module named “RS-Linx OPC Server”. The different PLC manufacturer gives their own server modules for HMI interface. Like, SIEMENS PLC has server module named “SIMATIC.NET”. The present invention renders a novel feature that it can render data access with any kind of Level I system. Hence the innovation was implemented for Rockwell PLC OPC server, however it can be used for any other Level-I automation systems like PLC and DCS of any make. The only change required is to change the specific name of PLC server from where data access needs to be established. The present invention is basically a client module implemented in a computer having a link with HMI network of Level I system as indicated in Fig. 3. The core of present invention is the developed client module, which in one hand renders a direct data access with PLC without any proprietary hardware using standard computer network card while in other hand communicates the fetched PLC data with Level – III ERP system through any standard relational database as well as Comma Separated Value (CSV) file.
As indicated in Fig. 2, the invention initializes COM or DCOM whatever the case may be. Subsequently, it creates an instance or copy of Level –I PLC server within its domain using the CLSID of server program as listed in the registry file of the computer. Subsequently, following the OPC standard, an OPC group is created with the designated PLC and defining the data update rate. As in this particular case of Sinter Plant of Bokaro Steel, there are only one set of PLC in the network as shown in Fig. 3, only one group has been created. However in case of several PLC’s in one network different groups needs to be created. The groups are also created using specific COM interfaces using the inheritance feature. Next the module assimilates the required process data, as defined in a separate file, with all its features like data type, required update rate etc. The tag name of the required data has to be exactly match with tag name defined in PLC; otherwise an error message will be displayed. The invention creates an array of desired process data as tag name and assimilates them under an Item name with specified address for individual tags. The invention features creation of different sets of process variable assimilated under different Item names. The different Items can subsequently be used for different purposes like some Item may be used for reading while other for writing to PLC etc. The process data tag assimilation is incorporated through a specific Connection Point Interface. The invention renders a very effective error message generation at each step to facilitate the user to easily identify the fault location and reason. Having successfully created a connection point with PLC process data, it is only required to either give read or write the required process data. In order to avoid, network jamming, asynchronous data read technique is used here. In asynchronous data reading, the client module will put a request for data access. However in case of asynchronous data access, Server puts the request in a queue and provides the data as soon as PLC processor is free. The creation of server instance, PLC group and data connection point is done during initiation of module. However, as per the requirement of Bokaro Steel ERP system, asynchronous read is executed at every
2 sec duration. The client module then extracts the requested data in its original data form like integer, float, string etc. Along-with data value the system also returns data quality and data time stamping. The invention only accepts the good quality data and eliminates out bad quality data.

The second part of the innovation is transferring the extracted PLC data to the ERP system database. For this client module directly opens the relational database using OLEDB and writes the data to a predefined specific location over network. The database can be SQL Server / Oracle or any other relational database. However in this particular case SQL-Server has been used as database. Thus the process data is updated in ERP database periodically at every 2 sec. This process data from the database is accessed by different modules of ERP for further display / reporting / analysis etc.

As an additional feature, the said module also converts all the data in a “Comma Separated Value (CSV)” file, which is also saved at a predefined location in ERP system with time stamping. The system has been implemented in a PC which is interfaced with PLC network over Ethernet TCP / IP. Fig. 2, below delineates the flowchart of developed software.

At the end the invention, to have efficient memory management, deletes majority of the created interfaces and data arrays. This is to avoid piling up of unwanted data in the computer memory at every iteration due to memory leakage. Finally the COM or DCOM is uninitialized.

Best Mode of Working

The developed system is implemented in a PC platform and software is written in VC++ (Microsoft Visual Studio). The PLC based control system is envisaged through a Rockwell Automation make Control Logix processor. The bidirectional data communication between expert system and Level – 1 PLC has been achieved through an OPC (OLE for Process Control) client software developed in VC++ and is an integral part of developed system. Rockwell Automation make RS-Linx has been used as OPC server. The detailed system architecture with critical process parameters are shown in Fig. 3.

Inventive step:

The novel features of the invention are explained below and protection shall be sought.
i. Development of a client modules / interface, which can access data from Level-I systems like PLC using concepts of OPC.
ii. Direct interface with PLC‘s OPC Server over HMI network
iii. Periodically updating of PAC’s data in ERP database as well as CSV text file.

Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration by way of examples and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. It will be apparent to those having ordinary skill in the art that a number of changes, modifications, variations, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

CLAIMS:-

1. System for interfacing Level-I system with Level-III system in an industry for automation comprising of:-
a PC platform;
a Level I, PLC based control system envisaged through a Control Logix processor;
a Lever III, ERP relational database;
a bidirectional data communication HMI network through an OPC server and (OLE for Process Control) client module configured for :-
initiating DCOM (Distributed Component Object Model) / COM (component object model) and creating an local instance of server;
creating a dedicated group for establishing connection with specified Level I system from Level III system through a client module; and
accessing and integrating the process data as asynchronous contact interface wherein the data is read periodically at an interval of a 2 sec.

2. System as claimed in claim 1, wherein the data of different types like integer, floating point, character string etc. are fetched and stored in a database.

3. System as claimed in claim 1, wherein the module encompasses connectivity with a relational database in Level III system, where all the data are stored with time stamping i.e. the event time recording.

4. System as claimed in claim 1, wherein the module also converts all the data in a “Comma Separated Value (CSV)” file, which is also saved at a predefined location.

5. System as claimed in claim 1, wherein the module also updates of PAC’s data in ERP database as well as CSV text file periodically.

6. A method for interfacing Level-I system with Level-III system in an industry for automation employing system as claimed in claim 1 comprising the steps of:-
initiating DCOM (Distributed Component Object Model) / COM (component object model) and creating an local instance of server;
creating a dedicated group for establishing connection with specified Level I system from Level III system through a client module; and
accessing and integrating the process data as asynchronous contact interface wherein the data is read periodically at an interval of a 2 sec.

7. Method as claimed in claim 6, wherein the data of different types like integer, floating point, character string etc. are fetched and stored in a database.

8. Method as claimed in claim 6, wherein the module encompasses connectivity with a relational database in Level III system, where all the data are stored with time stamping i.e. the event time recording.

9. Method as claimed in claim 6, wherein the module also converts all the data in a “Comma Separated Value (CSV)” file, which is also saved at a predefined location.

10. Method as claimed in claim 6, wherein the module also updates of PAC’s data in ERP database as well as CSV text file periodically.