The network — or a system of networks -»- may consist of at number of different types of networks
lo meet the functional and performance requirements of the enterprise hierarchy to be deployed. For
example, a variety of field area networks, and sensor networks, are used at the mannfacturittgf process
level. They are designed to support the exchange of small data records characteristic of monitoring and
control actions. and are connected to process controllers. The traffic. which exhibits low data rates, is
frequently subject to determinism of data transfer. To ensure the determinism, if mandated, the networks
can be segmented to distribute the load. The control network(s) are used to exchange real-time data
among controllers and operator workstations used for process control and supervision. There is a growing
tendency for this level of networks to he based on the Ethernet and TCPIIP protocol suite. The major
role play here field area networks that incorporate Ethernet for the lower two layers in the OSI model,
such as PROFlnet or EtherNet!IP: these are discussed in more detail in the following sections. Enterprise-
level networks are typically used for manufacturingfprocess execution and van'o|.ts enterprise manage-
mem applications. The traffic is characterized by high data rates and large packets: determinism of data
transfer is largely not an issue. These networks are predominantly based on the Ethernet and TPCIIP
protocol suite.