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Every vendor of WirelessHART devices is working on tools and guidelines for end users to help them design and install WirelessHART networks. “Currently,” says Endress + Hauser’s vice president, Victor Wolowec, “we are working on a detailed guideline for coexistence with other wireless networks. In addition we plan to have guidelines for site surveys, installation, and the operation phase.”
Samson AG’s product manager Guido Koenig agrees. “Samson has always provided technical information and engineering guides for digital communication. We will do that as well for HART 7.”
Many vendors are preparing design tool sets that make use of the capabilities of HART 7. Immediately upcoming for Emerson’s AMS is a new application to help users plan their WirelessHART networks. “This is a screen from the AMS Wireless Application planning functionality,” Citrano reports. (See center figures.)
“The planning mode allows users to customize their planning parameters to meet their specific needs,” he says. “In the lower screen image, the red circle around the pressure transmitter indicates that it does not meet the planning parameters chosen for this wireless network.”
According to Citrano, the application can also be used with networks that are already in operation.
“The upper screen shows the communication paths within the self-organizing network,” Citrano says. “This view helps users visualize the health and robustness of their WirelessHART network.”
Every WirelessHART network is self-organizing, so devices virtually maintain themselves. Each device can act as a router for other nearby devices, passing messages along until they reach the gateway. If there is an obstruction, transmissions are simply rerouted until a path to the WirelessHART gateway is found. As conditions change or new obstacles are encountered, these wireless networks simply reorganize and find a way to get the communication through.
On occasion, when a facility is seeing periods of high infrastructure activity or if devices are taken out of service, pinch points (communication bottlenecks) may develop. “Self-organizing networks can run indefinitely with bottlenecks,” Citrano says, “but users who are concerned with having an optimal wireless network may want to identify and take action to eliminate these pinch points.”
WirelessHART with EDDL enables applications such as the one described above to help users optimize their wireless networks by graphically displaying the communication pathways between devices to the gateway and alerting users to existing pinch points.
Plant engineers, operators, and maintenance workers can assure their IT departments that WirelessHART is secure and will not increase the overall plant exposure to malicious or accidental cyber incidents. WirelessHART uses 128-bit AES encryption, secure join keys, and individual session keys to ensure that only valid devices can join and pass information in the network. A WirelessHART device can only join the network through a secure, wired connection. End-to-end encryption is employed to prevent sensitive data from being intercepted. The use of individual encryption codes and passwords on a point-to-point basis provides secure authentication for WirelessHART.
Wired or wireless, HART 7 is not your Daddy’s HART standard.
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