What is the role of data acquisition and monitoring control (SCADA) system? SCADA Supervisory Control And Data Acquisition system is the abbreviation of English, the popular name for the configuration software. Literally, it is not a complete control system, it is located on the control device, which focuses on the management of pure software. SCADA control equipment is usually PLC (programmable controller), can also be smart table, board, etc..
Early SCADA runs with UNIX, VMS, DOS. Most running in the Windows operating system, some of which can run in the Linux system.
Monitor system diagram
SCADA is not only used in industrial fields, such as steel, electricity, chemical, but also widely used in food, medicine, construction, scientific research and other industries. Its connected I/O channel number ranging from tens to tens of thousands. SCADA system manufacturers Shenzhen autoware below its SCADA system structure, function, interface and development tools to be introduced.
1.SCADA system architecture
1.1 hardware structure
Usually SCADA system is divided into two levels, that is, the client / server architecture. Communication between the server and the hardware device, the data processing He Yunsuan. While the customer is used for human-computer interaction, such as the use of text, animation display the status of the scene, and can be on the scene of the switch, valve operation. In recent years, there is a level, through the Web released on the Internat monitoring, you can think that this is a super remote customer".
The hardware equipment (such as PLC) not only can be connected by point-to-point mode, also can connect to the server on the bus. General point-to-point connection through the serial port (RS232), the bus can be RS485, Ethernet connection. Bus and point-to-point difference mainly lies in: point-to-point is one to one, and bus is one to many, or many to many.
In a system can be only one server, can also have a number of customers can also be one or more. Only one server and a client, and the two is running on the same machine is usually said the single version. Between the server, the server and the customer is generally through the Ethernet interconnection, some occasions (such as the security consideration or distance) also through the serial port, the telephone dial-up or GPRS way connected.
1.2 software architecture
SCADA has a lot of tasks, each task completes a specific function. Server is responsible for data acquisition, data processing (such as range conversion, filtering, alarm check, calculation, event recording, historical memory, execution of user script, etc.). Inter server communication. Some systems further separate the server into a number of specialized servers, such as an alarm server, a record server, a historical server, a log server, etc.. Each server logic as a unified whole, but physically may be placed on different machines. The advantage of classification is that the data can be unified management, division of labor, the disadvantage is low efficiency, local failure may affect the whole system.
Typical hardware configuration diagrams are as follows:
1.3.1 internal communication
Between the client and server, as well as between the server and the server generally have three kinds of forms of communication, the request type, the subscription and the broadcast type. Request: a client server requests periodically, then the server client data, is sent to the client.
Subscription type: the client registers the data to the server, and the server records the data for each user. When the data changes to notify the corresponding user.
Broadcast: when the data changes, the server sends a notice to all customers.
Communication between 1.3.2 and I/O
1) communication mode
Device driver and I/O device communication generally use the request, most devices are supported by this communication, of course, some devices support the initiative to send the way. Active transmission mode that is the I/O device to the outside world report data when the data changes. Some devices also support subscription based communication. Device drivers should be able to support a variety of communication modes.
2) communication protocol
The communication protocol, which is a kind of communication protocol, can be understood as a kind of simple communication protocol. These languages have a certain place, especially in the domestic PLC, intelligent instrument. Common protocols such as Modbus, Profibus, etc.. Device drivers must be prepared for each protocol. Development of a device driver for 1~5 weeks, which depends on the complexity of the protocol. Software providers generally will be part of the standard development kit, users can develop their own.
The server can also have many different types of drivers, so that the server can simultaneously communicate with a variety of devices.
1.3.3 communication with the outside world
In order to efficiency, the real-time data and historical data on the server are stored in private format, the real-time data resides in memory, and the historical data is stored in the disk, the event record may be stored in the disk, but some software can be stored directly to the relational database (such as SQL Server Ms, ORACLE). Because the speed is relatively slow, the speed is relatively slow, so it is not possible to store the fast changing data in the relational database. Then how the data in the server is connected to the outside world, a brief description of the.
SCADA through a variety of ways to communicate with the outside world. Such as OPC, the general will provide the OPC client, used to provide OP
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