All around us we live day-to-day with wireless technology. Routers, smartphones and TVs all use the technology, yet in industry there is a certain reticence towards embracing wireless communication due perceived difficulties. But are these justified? Read the below and see what you think.
- WirelessHART is unsafe
Wrong. By using an Advanced Encryption Standard (AES) system, all communications are encrypted making WirelessHART networks incredibly safe. Other security benefits include restricted access to new network subscribers without prior permission and join counters that ensure unrecognised substitute devices are rejected by the gateway.
- WirelessHART networks are expensive
Whilst WirelessHART networks may carry a higher price tag, initial outlay should not be confused with total cost of ownership. Wired devices require add-ons which WirelessHART networks do not, such as cabling, cabling trays and junction boxes. All these components need to be bought, prepared and installed, quickly bumping up costs before a network is even functional, with additional time and costs being incurred throughout their lifetime through checking and maintenance.
- WirelessHART networks are unreliable
Not true. WirelessHART is more reliable than cabled networks, thanks to time-synchronised, frequency hopping, meshed networks. What this means is that the gateway creates communications paths that are empty and can be used should one path fail. Transmitted data packets can hop around, from node to node, identifying the most stable communication path before reaching a communication endpoint. This setup also makes it very easy to detect broken links for repair.
- The range of WirelessHART networks is too short
If robust setup recommendations are followed, WirelessHART network coverage will often reach to approximately 300 feet. Strong coverage can be achieved by installing three devices within range of each other and the gateway in the middle of the network. This also helps to eliminate pinch points which can risk network failure and shorten battery life. Network coverage can simply be expanded by installing further measuring points, which automatically increase the network as every new WirelessHART device will re-route data packets from other devices.
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WirelessHART devices constantly need new batteries
As is the nature of wireless communication, devices need batteries to remain truly wireless. And yes, batteries will need to be replaced. However, there are simple steps to follow to ensure battery life is prolonged. All WirelessHART devices have a specified update rate, defined as the moment a device measures a process and transmits the data to the gateway. If update rates are kept to four seconds or more, this can have a positive impact on battery life. If update rates are slow enough, devices will enter a “deep-sleep mode”, helping to conserve even more energy.
Furthermore, where energy harvesting technology is used, thermal energy from steam travelling in pipes can be used to create a voltage, which can be used to power a WirelessHART device. In this instance, batteries become a secondary power supply and are only used if insufficient thermal energy is available.
- WirelessHART requires specialists to set up
Setup is actually pretty simple. All you need is a WirelessHART device, a gateway that communicates between the host application and the device network and a set of network parameters (network I.D. and a join key). Installation is not as simple compared to wired HART devices but is less tricky with no requirement for cabling. This also benefits installations in hazardous areas, with WirelessHART devices requiring only an intrinsically safe power module rather than the paraphernalia needed for ensuring the safety of a wired device.
- WirelessHART is too slow
WirelessHART provides a speed of 250,000 bits per second, which is 200 times faster than wired HART and six times faster than HART over RS-485 cables. If that’s not enough, then speed and performance can always be adjusted as the update rate can be configured between once per second or once per hour. As most WirelessHART devices monitor applications rather than control them, update rates can easily be set at over one second to maintain a reliable network speed.
Contrary to some views, WirelessHART devices are more than capable of replacing traditional wired HART systems. If installed correctly, networks can be faster, more reliable and cheaper when total cost of ownership is considered.
To find out more about ABB’s WirelessHART offering, visit http://bit.ly/WHARTmyths
