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Unlike the second generation, this generation is based on an open system architecture rather than vendor controlled, proprietary solutions. One of the major differences is that the third generation can utilize open standard protocols and products. Consequently, SCADA functionality can be distributed across a WAN and not just a LAN. For instance, most field devices such as PLCs and RTUs can be connected directly to the MTU over an Ethernet connection. This open system architecture allows various products from different vendors to be integrated with each other to build a SCADA system at low cost. In addition, a remote field device can be supervised and controlled from any place and at any time using the Internet. Figure 2.3 shows the architecture of a typical networked SCADA system.