In industrial control settings there are a number of ways that Opengear appliances can be used to securely interconnect remote RTU and PLC serial devices to the SCADA system in the central office - using DNP3 and Modbus communications protocols.
- Most control applications at the central control station run on Windows or Linux computers, and often the application will communicate with the RTUs and PLCs over COM or TTY ports. In this situation Opengear's free Portshare software can be deployed on the central computer to encapsulate the DNP3 and Modbus data stream in IP. Portshare then communicates - over the Internet or cellular or wireless or locally wired TCP network - with a remote Opengear appliance which is serially connected PLC or RTU at the remote site.
For more detailed information on using Portshare refer faq234.
- Newer SCADA applications provide the conversion to IP themselves. So the SCADA master application encapsulates the DNP or Modbus data into TCP packets and sends it off to the remote serial device over the IP network. At the remote site an Opengear appliance converts the packet back to a serial data stream for connection to the target PLC or RTU serial device. The target serial device at the remote site is identified via a TCP Socket connection - using the Opengear appliance’s IP address with a TCP port number corresponding to the individual serial port (e.g. 126.96.36.199:2001).
For more detailed information on communicating with serial port connected devices refer faq242.
- Some legacy control appliances have their own physical serial ports - and these can still connect to remote devices by using Opengear devices servers in back to back "serial bridging" mode to IP-encapsulate the DNP3 and Modbus data streams.
For more detailed information on serial bridging refer faq254 and refer faq278.