Implementation of OPC2OPC in Remote Monitoring

1. Introduction

Network communication technology is the most critical technology in remote monitoring technology. However, network communication generally uses Socket technology, or even FTP or Email, etc. These technologies are greatly lacking in terms of data volume, programming flexibility, and security. Secondly, there is the problem of coexistence of multiple structures in network communication. Most of the current remote monitoring system structures are relatively complex, with long distribution distances, and there are also different LANs, different platforms, and even different operating platforms and programming languages ​​in the same LAN. This requires integrating different platforms in the network to achieve mutual communication, and these problems are difficult to solve using traditional methods. This article introduces a set of standard remote monitoring tools that use the industrial standard OPC data interface. Users can realize remote transfer of standard OPC interfaces without any development, and then realize remote online monitoring through configuration software that supports OPC interfaces or other visual OPC client software. At the same time, it realizes functions such as data storage and processing, trend trends, data query, and report printing.

2. Introduction to OPC2OPC Tools

Considering that the control systems currently used on-site by large factories and enterprises are mostly products of Siemens and FF fieldbus, and these manufacturers all provide OPC servers that match their own hardware systems, such as Siemens OPC servers, FF fieldbus OPC servers, etc. This provides users with a third-party data interface. Through this standard OPC data interface, the OPC2OPC tool can be used to remotely transfer the OPC server interface on-site without changing the variable names defined on-site, and there is no impact on the site. The interface transfer diagram is as follows:

As shown in the figure, a remote monitoring system based on the combination of OPC technology, network technology and configuration software technology is realized, which is mainly used in the field of industrial automation remote monitoring. Its leading idea is to realize the remote transfer of OPC data interface through OPC technology and Internet network technology that conform to industrial standards. At the same time, the most popular configuration software technology in the industry is applied to realize remote monitoring and diagnostic analysis of the production site. The system includes two parts: the on-site OPC2OPC server software that conforms to the OPC standard and the OPC2OPC client software of the remote client. The whole system can be integrated with the distributed FF fieldbus that supports the OPC interface, and can also be integrated with the PROFIBUS bus of Siemens in Germany, to realize remote monitoring of the on-site equipment status and the production process status without affecting the original on-site monitoring. As can be seen from the figure, due to the characteristics of the network, the system can be distributed in the form of C/S (client/server) structure for remote monitoring, which better meets the needs of users.

3. Functional Description

1.OPC2OPC server complies with OPC standard specifications 1.0 and 2.0.

2. Network communication complies with TCP/IP protocol and can communicate on the Internet/Intranet.

3.OPC2OPC client complies with OPC2.0 specification and provides standard OPC interface.

4. The software has the function of automatic reconnection in case of disconnection.

4. Application of configuration software

Configuration software, also known as configuration monitoring software system software. Translated from English SCADA, it is Supervisory Control and Data Acquisition. It refers to some special software for data acquisition and process control. They are software platforms and development environments at the first level of the automatic control system monitoring layer. They use flexible configuration methods to provide users with general-level software tools for quickly building industrial automatic control system monitoring functions. Configuration software has a wide range of applications and can be applied to data acquisition and monitoring control and process control in power systems, water supply systems, petroleum, chemical industry and other fields.

When the OPC interface on site is remotely transferred to the remote client through the computer network, the client can remotely configure the equipment status information or production status information. Due to the standardization of the interface and the integrity of the interface transfer, the variable names on site do not change at all, and the user can configure at a glance, just as if it were on site. At present, there are many configuration software products, such as the domestic King of Configuration, Kaiwu, etc. As long as the configuration software complies with the OPC interface specification, it can perform human-machine interface monitoring.

5. Data remote refresh rate

Data collection and remote transmission take a certain amount of time, especially when the amount of data on site is large or the network bandwidth is limited, there will be a large delay. In order to ensure the needs of data transmission and the stability of the system, the tool currently has a remote refresh rate of 1 to 2 seconds in a system with 200 monitoring points, and a refresh delay of 8 seconds for 1,000 monitoring points. Of course, it can be further improved according to the needs of users and the specific network environment, and the refresh can be faster to meet the user's needs for data refresh speed.

VI. Conclusion

Based on OPC technology and network technology, the remote transfer of standard OPC interface is realized, and the space for users to independently apply in the configuration and production of human-machine monitoring interface and the selection of configuration software is left, which is convenient for users to give full play to their own application level and also brings great flexibility to the combination of systems. The OPC2OPC tool provides a new remote monitoring channel and solution for the remote monitoring system at a low cost and in accordance with the standard OPC interface. The OPC2OPC tool is easy to use and meets the requirements of enterprise remote monitoring.