The backbone of industrial wireless networks
The IEEE 802.15.4 standard fully defines a robust wireless personal area network (PAN) that specifically targets low-power, low-bandwidth networks commonly used in industrial monitoring and control.
Here’s how it works: An IEEE 802.15.4 transceiver integrated with an industrial switch or sensor communicates to a monitoring receiver that can handle multiple switches in a star-configuration network. Every network, and each wireless device in the network, has a unique identification number that allows the device and its associated monitor to encode their signals. This ensures that the communications link between them is private and virtually immune to crosstalk from other switches or networks.
These 802.15.4 radios provide excellent results in large indoor open spaces and/or outdoor installations with a relatively open line-of-sight between device and monitor. A 35dB link margin ensures that minor obstacles or even heavy precipitation will not compromise communications. In some installations, the signal can penetrate intervening walls, depending on their materials.
Based on 802.15.4 point-to-point communications, Honeywell’s Limitless switches can be configured with up to 14 devices to communicate with one receiver module. The wireless signal is received by either a panel-mount receiver, or an industrial DIN-rail module, which is then converted to an output. Outputs can be LEDs, buzzers, or standard electrical signals used by traditional controllers.
The allowable operating range of an IEEE 802.15.4 radio is more than 1,000ft (304m). In extreme conditions such as heavy precipitation, rain, or snow, the signal could be reduced by approximately 75ft (23m).
Because 802.15.4 devices draw so little power they can be operated by industry-standard batteries, which ensures reliable operation and provides for almost limitless options for installation. It also eliminates the need for situation-dependent, unreliable, and expensive energy scavenging. A wireless sensor or switch may operate for several years without a battery replacement or recharging, depending on the design.
Typically, the monitor/receiver unit in a wireless network can support either a single device or multiple devices. For example, the Honeywell Limitless WDRR receiver can support up to 14 different remote, battery-powered, wireless devices. In addition to continuously monitoring the sensor and switch status, the controller can also monitor the signal strength and battery levels for each individual device on its network. If a battery starts to die, or a switch gets blocked, the operator will know instantly and can take corrective measures.
Wireless on/off controllers are also available. Powered by batteries, these wireless operator interface devices can be located for easy operational access without spending a lot of time to connect them to the control network or to a power source.
Because 802.15.4 is a PAN standard, it operates independently of other common wireless LAN technologies such as Bluetooth, WiFi, and cordless phones. This means there is no exchange of information or other interaction between a PAN and the LAN, eliminating the need for corporate IT department involvement.