Hot Off the Wire

In 1974, when I first entered the building controls business, electronic hardware was more costly than the labor to install it. Here, 34 years later, that comparison inverts – installation is more costly than the hardware. Emerging wireless technologies now eliminate network cabling. We will always have localized wiring between controllers, sensors and actuators.

Rockwall Controls uses and has used a variety of wireless technologies. In the late ‘80’s we installed and service power-line carrier technology by Honeywell, that is until the advent of electronic fluorescent ballasts. Non-linear loads, like electronic ballasts, introduce harmonics that easily defeat older power-line carrier products.

Anytime one chooses to deploy wireless control systems, he/she must consider time - time to convert measured variables, time to process that variable and time to reposition a final control element (valve, damper, etc.). It is entirely possible to have all the pieces in place and be unable to achieve desired results due to latency in analog-to-digital (ADC) conversion, digital-to-analog (DAC) conversion and data transmission.

Over the last fifteen years, our choice for local control networks has been LonMark FTT-10 (EIA-709), a creation of the Echelon Corporation. Our real passion is open-systems protocols, better described as non-proprietary protocols like LonMark, BACnet and MODBUS. We are dispassionate about which open architecture we use, although LonMark products have the greatest global market share. Naturally, at the top of the heap is the IP network.

Products we successfully used recently for critical indoor climate control of a zoological facility are the 2.4 GHz Nico wireless temperature-relative humidity transmitters. Distance is the most important limitation. We could only separate transmitters from receivers a maximum thirty feet, but the receiver readily connects to an existing FTT-10 network. After several months of use in a hostile (humid, lizards) environment, they continue working reliably.

Until recently, long-range (> 5 miles) IP connectivity demanded costly (as in $20,000 per point) microwave equipment. Low-noise, low-cost IP microwave connectivity cost is now under $1,000 per point. Low-power equipment operates license-free and powers over Ethernet (POE) to simplify installation.
IP tunneling routers and switches have for some time encapsulated and transported low-level LonMark data over existing facility local area network cabling, thereby eliminating costly hard-wired networks. Nevertheless, it gets even better with the new Sedona FrameworkTM technology announced by Tridium May 19, 2008. Tridium plans to open-source the protocol and programming. Target markets are embedded appliance products. Hill-Rohm, the largest manufacturer of hospital beds, chose Tridium JACE controllers with Sedona FrameworkTM for its next generation bed products. Bed controllers wirelessly and automatically associate all manner of portable equipment (pumps, monitors, etc.) with the patient with the objective of improving nursing efficiency and accuracy. Because Sedona uses IP communications, data freely moves over the hospital network routers and switches without need for tunneling.