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Control-networking technology delivers smaller, cheaper nodes
By Maury Wright -- EDN, 9/19/2005
Echelon, the developer of the LON (local operating network) sold under the LonWorks brand, now has a new technology, Pyxos, that the company claims will be cheap enough to connect sensors and actuators in everyday equipment. Designers have commonly used LonWorks products to automate building control in lighting, HVAC, security, and other systems. But generally, LonWorks would prove too expensive to use in a control network within a product such as an air conditioner or spa controller. Echelon believes that Pyxos will bring connectivity into such systems.
The benefits include simpler design because a low-cost, free-topology wiring system can connect sensors and actuators in place of traditional wiring harnesses—a benefit similar to what CAN (controller-area-network) technology brings to the automobile. A Pyxos-enabled appliance could also allow a user to perhaps use a cell phone to remotely control a device such as a spa. And manufactures could enable preventive maintenance on Pyxos-enabled products. Alas, Pyxos doesn’t seem to offer much toward a truly automated home for the broad consumer base because the cheapest Pyxos chips will still sell in the $2 to $3 range in low volumes.
From a software perspective, a Pyxos node can operate just as a LonWorks node, and designers can link subnetworks of as many as 32 Pyxos nodes to a LonWorks network through an access point. Alternatively, a designer could use Pyxos chips alone in a network without LonWorks. The Pyxos nodes share the transceiver technology in LonWorks, including RF, power-line, and twisted-pair technology. Twisted-pair cable can carry both the data signal and the power to Pyxos nodes. And designers can connect Pyxos nodes in bus, star, and loop topologies.
In its simplest form, a Pyxos node requires only a Pyxos chip, a transceiver, and the connection to a sensor or an actuator. The baseline Pyxos chip includes digital I/O to connect to simple sensors and actuators and needs no on-board microcontroller. Instead, vendors can preconfigure Pyxos chips at the factory, and the nodes self-install themselves into workable networks. More complex nodes might include a microcontroller, data converters, and LonWorks links.
Echelon claims that, together with partners, it has deployed more than 50 million LonWorks control devices. Company Chairman Kenneth Oshman projects that the potential Pyxos market is two orders of magnitude greater than the LonWorks market. The company predicts scenarios as wild as a smart carpet that can track traffic patterns so that cleaning crews concentrate on busy areas.
Echelon Corp, www.echelon.com.
