is a low-cost communications link to connect industrial devices (such as limit switches, photoelectric sensors, valve manifolds, motor starters, process sensors, bar code readers, variable frequency drives, panel displays and operator interfaces) to a network and eliminate expensive hardwiring.
The direct connectivity provides improved communication between devices as well as important device-level diagnostics not easily accessible or available through hardwired I/O interfaces. DeviceNet is a simple, networking solution that reduces the cost and time to wire and install industrial automation devices, while providing interchangeability of "like" components from multiple vendors.
The DeviceNet communication link is based on a broadcast-oriented, communications protocol - the Controller Area Network (CAN). The CAN protocol was originally developed by BOSCH for the European automotive market for replacing expensive, wire harnesses with low-cost network cable on automobiles. As a result, the CAN protocol has fast response and high reliability for applications as demanding as control of anti-lock brakes and airbags. Chips are available in a variety of packages with high temperature ratings and high noise immunity, attributes well suited for the industrial automation market as well.
But it is consumer and commercial demand for CAN that is the key driver in lowering the price and increasing the performance of CAN chips. In 1994, four suppliers of CAN chips (Intel, Motorola, Philips, Siemens) shipped 4+ million CAN chips. Over 10 million chips are expected to ship in 1996. Whereas other industrial automation networks use custom chips with annual demand varying from 20,000-200,000 per year, DeviceNet products use the same CAN chips as are used in automotive and other consumer/commercial applications. The chips for DeviceNet products are typically 5-10 times less than chips for other networks.