If you are still concerning about the high price of wireless solutions for industrial control system, you must learn about the new product launched in June 2009 by ICP DAS: The Serial-to-ZigBee converters
ZB-2550P and
ZB-2551P! ICP DAS new released ZB-2550P and ZB-2551P wireless Converters will help you to solve above problems, reduce the wiring cost, and achieve the mission of remote I/O control and data acquisition. The typical transmission distance between the ZB-2550P and ZB-2551P is 700 meters.
ZigBee is a specification based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs). It can reach a maximum baud rate of 115,200 bps, which is sufficient for industrial control. Other than lower cost, ZigBee also features stability, safety, flexibility, mesh nodes and convenience comparing with other wireless communication specifications.