In the industrial automation sector, cabling is one of the 
large portion of the cost. Therefore comes the idea of fieldbus.
Instead of one to one cable connection (each sensor to PLC/DCS),
you will have multi-sensors connected to a bus (eg. ASi bus -- 
actuator sensor interface), then through a gateway (eg: ASi 
to Profibus gateway), all the sensors are connected to the 
PLC/DCS.

Now comes the wireless, you cut the last "mile" of cable from
the system. The problem with Zigbee is still the with current
consumption and cost. Adding 10s of mA to a sensor which only
consume less than 100mA is a lot. Adding US$5 to a US$25 sensor
is as well quite a lot. The space is another issue even though 
PCB antenna is getting smaller. Another obstacle is that this 
sector is quite conservative. The PLC/DCS makers control the
market (Siemens, ABB, Honeywell, Rockwell, Invensys, Yokagawa, 
Omron, AB, etc).

Chipcon seems to be the leader now. Parts from Freescale are
now very expensive.

Regards,
Xiaofan

-----Original Message-----
From: Richard Prosser [mailto:rhprosser@gmail.com]
Sent: Thursday, June 02, 2005 7:16 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Wireless Sensors


Look at ZigBee (www.zigbee.org ?)
Chips Maunufactured by Freescale, Atmel, Chipcon & a few others.
Microchip support for the Chipcon version using an 18 series micro.

RP
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