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Internet and Web-based SCADATraditionally SCADA communications has been Point-to-Multipoint serial communications over lease line or private radio systems (i.e. RS232, RS485, BEL202).With the advent of Internet Protocol (IP), IP Technology has seen increasing use in SCADA communications. Internet SCADA or Web-based SCADA makes use of IP technology in SCADA and can range from IP tunnels over satellite, frame relay, fiber, radio to link SCADA networks to central office to individually IP addressed instruments or devices or web-based SCADA Host MMI Software such as NETSCADA.. ADVANTAGES AND DISADVANTAGES OF INTERNET & WEB-BASED SCADA Advantages of INTERNET & WEB-BASED SCADA
Disadvantages of INTERNET & WEB-BASED SCADA
IP TECHNOLOGIES FOR INTERNET SCADA The following is a list of common IP technologies and functions and how they are applied in Internet SCADA systems. Cellular data modems enable wireless connectivity to a TCP/IP network. CDPD and IDEN modems allow IP hosts to reach remote site SCADA & Telemetry equipment like RTU's, PLC's, dataloggers, flowcomputers & VFD's.. Wireless Ethernet Radios Increasingly, newer PLC's and RTU's are incorporating Ethernet interfaces. Wireless Ethernet radio enable IP connection to these newer Ethernet-enabled devices. Wireless Ethernet can also be used to bridge remote SCADA networks together. Tunneling over the Internet If secure SCADA communications is required over the public internet, VPN's (Virtual Private Networks) can provide the level of needed security. A VPN is a private network created on top of the public internet. Clients use VPN to create a secure and private "tunnel" to the Server with the security being provided by the VPN's user authentication and data encryption. Serial to Ethernet Gateways / Terminal Servers These devices enable serial devices to communicate over TCP/IP networks or allow IP hosts to reach Serial devices using the TCP/IP network. Web Server Web Server technology has enabled low cost web browser technology to be used as the MMI for PLC and SCADA systems. Newer PLC's and RTU's frequently incorporate web servers that allow diagnostics and monitoring function via user web browsers. Web-enabled SCADA hosts enable users to remotely monitor, control remote sites via a web browser. Hosted SCADA services are being offered that allow users to monitor or control their remote equipment by using a normal web browser and logging onto a secure website.Email for Alarms or Reports Internet SCADA systems can use emails for alarming or reporting. When an alarm occurs, alarm emails are sent out to email-enabled cell phones and P.C.'s. FTP for File Transfer FTP stands for File Transfer Protocol. This can be used in Internet SCADA to transfer files between Host and Remote sites for Data logging, Reporting or Configuration. Telnet for Remote Configuration Telnet is an IP-based remote access utility used in Internet SCADA to remotely configure RTU, PLC and other SCADA equipment. TCP, UDP for Data Communicatiaons TCP is a Internet protocol used to ensure reliable End-to-End communication. UDP is a much simpler Internet protocol which does not check for End-to-End communication reliability. Consequently, UDP is much faster (because it doesn't do any checking) but is not as reliable. The choice of which to use is dependent on the SCADA application. TCP is typically used for applications like alarming where the information is critical and cannot be lost. UDP is used when throughput is more important than reliability. IP Protocols IP protocols enables data to be routed over the Internet. The most common 2 protocols used is TCP/IP which results in reliable routable End-to-End messaging. Ping This IP utility is used to check if a remote SCADA device is accesible. Like a normal PC, the remote SCADA device must respond with a Ping reply if it sees a Ping message destined for it. If there is a timeout instead, this inidicates a problem exists with the device or the network path.
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Bentek Systems SCADA & Telemetry Solutions |
504 - 42nd Ave.S.E. |