Application of VB in data transmission of remote pipeline network

Communication of remote measurement and control terminals in water supply SCADA system my company used to be through wireless digital radio to achieve, due to the external interference is too large, too high temperature prone to cause frequency deviation, resulting in frequent data is not received, with the water supply network remote detection and monitoring technology of the continuous development and progress, Now the popular CDMA or GPRS wireless communication in the stability or accuracy of the win, and in the speed of quality improvement. In view of this, in the SCADA system for the remote measurement and control terminal communication, in the hardware we decided to use CDMA wireless communication equipment to transfer data to replace the past wireless digital radio station.

The concrete structure is shown in the following figure:

My company's SCADA system in the collection end with the Simens s7-200 PLC, the transmission of data using the free mouth communication, so you can connect with the RS232 serial port of the CDMA equipment (a60i), the device using the transmission mode, embedded TCP/IP protocol stack, In the transmission mode of the serial port input data through the CDMA network and Internet network through to the server, so that in the CDMA devices set up the server's public network IP address and port number, remote data can be wireless networks and the Internet to upload data to the SCADA system's main server, The SCADA system upper unit State software is InTouch 7.0.

Because the host unit State software InTouch 7.0 does not support the direct communication with the subordinate machine, therefore must write the application to connect the upper and lower machine.

VB is an object-oriented programming language for developing Windows applications, it supports the DDE communication mechanism in Windows environment, and provides the programming interface of DDE. DDE (Dynamic Data exchange). is a standard for data exchange between different programs in the Windows operating system. This standard allows your program to automatically receive data from other applications, any changes to the data on the transfer side, and the receiving end can automatically update. Same Your application can also transmit data to other applications. InTouch supports the use of DDE data interchange to send and obtain data.

In addition, the Winsock control in VB can achieve point-to-point communication. This allows communication to be established with the remote measurement and control terminal point one by one.

Therefore, it is a good choice to compile the VB program to connect the remote control terminal with the host unit State software. The process is shown in the following illustration: