1.2.2   Network Architecture

Network Design

There is no limit to the number of SCADA nodes or Clients in a network (other than licensing requirements).  Typically, there is only one project node (the second would act as a backup database server or a redundant web server).

Figure 1.10  WebAccess Network Drawing

Your network design will affect the overall performance of your system. Considerations include:

·         Physical Location of Automation Devices including PLCs, Controllers, and Network Access points (Geography).

·         Throughput required (i.e. SPEED of Display updates).

·         SCAN time of Devices

·         Protocol

·         Network Characteristics (traffic, number of nodes)

·         Number of users

·         Device Driver

·         The speed of the PLC or Device

·         How many tags can be read in a single request from the PLC