The number of Controller Area Network (CAN) nodes is growing exponentially. Tens to hundreds of sensor nodes are linked on the CAN network of every modern car nowadays, and the same can be said for trucks, buses and machinery. But imagine a CAN network encompassing some 60,000 nodes or more over a distance of several thousand acres? Some of the largest CAN networks today can be found in power generation, most notably in solar fields. Here, CAN is being used as a means of communication between thousands of ground-mounted mirrors used to concentrate sunlight and the solar field’s control centre.
An example is one of BrightSource Energy’s Israeli based pilot solar fields. Brightsource is a Kvaser customer that uses CAN to control and monitor its ‘heliostats’ – a term used to describe the mirror, its support structure, pylon and tracking system. Each heliostat has a 2 axis controller that allows the mirrors to be tilted up and down and from side to side to track the sun. Their reflected solar energy is focused onto a massive boiler where water is heated to more than 1,000 degrees Fahrenheit to create super-heated steam, which drives turbines in the conventional way.
With each CAN bus capable of controlling approximately 100 heliostats, the average solar field can have as many as a few hundred CAN networks running simultaneously These are linked using ‘gateways’ that connect one or two Ethernet ports to a set of between four and eight CAN buses.
Israel-based LogiCAN, a Kvaser Techical Associate, provided CAN engineering design and support to BrightSource for their project, designing a pc-based gateway that provided two-way communication between the control centre and each heliostat. Four of Kvaser’s CAN PCI boards were used for the implementation. “These proved faultless and were very easy to accommodate, thanks to Kvaser’s easy to use driver software,” said Ran Weiss, engineering manager of LogiCAN.
Since the pilot project, LogiCAN has remained the Gateway keeper and embedded developer for projects CAN-related for BrightSource. Its most recent project has been to develop a new CANopen based protocol for the next generation of BrightSource’s heliostats and an embedded gateway, which LogiCAN has also designed.