For several decades, PC-based solutions have been widely used for data acquisition and control in industrial automation. Early implementations relied on expansion cards inside a PC to attach I/O devices such as sensors, switches, alarms, etc. However, this solution was not effective over long distances due to the inherent limitations of I/O signal transfer. Serial remote I/O modules were later developed, allowing wiring to be extended over greater distances. However, serial remote I/O was unable to handle demands for long-range, multi-point monitoring and control.
White Paper: A New Generation in IP-based Data Acquisition and Control, from MOXA
Network hosts typically have to poll the I/O server repeatedly in order to obtain remote sensor data over an Ethernet network. This white paper presents a new approach to IP-based data acquisition and control that is dramatically faster, more flexible, easier to configure, and easier to program for.