Process Control Across Network

In recent times the explosive growth in computing and networking abilities has occurred. This has caused an increased reliance on distributed computing and process operations across the networks. The main aspect in the process control via network is the network delay, which depends on the network type and protocol. This paper gives the literature review about the network-based control systems and the methods developed for handling and compensating the network delay in a control loop. In the experimental part the research environment for examining the control performance of a laboratory-scaled process via three different networks is described. The networks are Ethernet LAN, Internet and FUNET, which is the network operating between the universities in Finland. This means that the distances between the operator and the process to be controlled vary remarkably from twenty meters to several hundred kilometers. Also the transmission speed of the network is different. The network delays are measured and compared with each other. Also the loss of data packages in different networks is examined.