Now that we are more familiar with common elements and architectures of ICS, let’s look at how information moves within a control system, starting with network topologies and methods. ICS or network topology refers to how the network is built from the ground up, where things connect, and how the information flows through this foundation. Now we are going to look at the physical layout of the network and define how different devices are connected.
ICS network topologies are similar to IT topologies. However, there are some fundamental differences critical to ICS applications. ICS networks require redundancy to ensure availability, which is not a common practice in IT. In addition, many older ICS networks use proprietary technologies, which are not used in the IT domain.
Some similarities that an IT network engineer might notice are the serial technologies. RS232, RS485, and Ethernet reside at the physical layer in the OSI stack and are common to both domains. RS232, which is an older technology in the IT domain, is still commonly used for point-to-point communications in RTUs and PLCs. RS485 is the foundation for many proprietary control networks used at site facilities. Click the icons below to learn more about these topologies.
Bus, Ring, Star