Wireless Integration for Better Performance of Process Instrumentation
also coexistence strategies to avoid message collisions with other nearby networks.
WirelessHART-enabled devices use a mesh network where alternate routes to get the information back to the gateway and the host system are available. If one pathway back is broken then an alternative path is selected automatically. When coexisting with other neighbouring networks WirelessHART employs the following strategies to make sure it gets the message through with minimal effect on other networks using similar frequency channels:
• •
Channel hopping: Each message automatically uses a different frequency channel from the previous message to avoid other networks (there are 15 channels from which to select).
Channel assessment: The transmission channel selected is tested to see if other networks are using it before the data are sent (i.e. avoids data collisions).
Replay Attack
Summary
Wireless networks, at the instrument level, may not replace 4–20 mA loops but will complement them where installation is difficult or expensive or where there is value in unlocking information left stranded in the field. Wireless adapters can be used to add wireless connectivity to existing HART instruments and provide an effective maintenance network back to the host system. Wireless adapters, such as the ABB FieldKey, can be fitted point by point and provide full access to the information stranded within the target instrument.
Spoofing
The use of wireless standards such as WirelessHART provides solutions to the major concerns of both reliability and security with built-in features to simplify engineering and integration into the host system. There is a series of international WirelessHART roadshows which can provide you with more information and application examples to help you identify the potential use of wireless in your process plant. n
Figure 4: Multiple Layer Security Denial of Service Spoofing Rogue Devices
Channel Hop
Join Encryption
Massage Integrity Checking
Passwords
Health Reports
Encryption Time Division Whitelist Data Privacy
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