The gateway automatically optimizes the mesh network and redundant pathways. It continues to monitor the mesh and adapts it as new devices join or the radio environment changes. This self-building and self-healing feature provides the reliability of data communications industry requires.
How are the issues of security addressed? Security at chemical plants is a huge topic in its own right (see the articles Get ready to comply with new security mandates, Feel Secure about Vulnerability Assessments, and Plug cyber-security gaps. Wireless HART makes security of data transmitted a key part of its core technology. For WirelessHART, security is always switched on. Built-in features address the issues of data security and outside interference. Some of the security methods used include:
- Keeping data transmission bursts short (10-msec time slots) (Figure 9). This makes it hard to synchronize and read messages.
- Authenticating devices as they try to join the network (join key, device key) and monitoring attempted joins. This will help to stop unauthorized devices joining the network.
- Encrypting each message. WirelessHART also allows the user to rotate encryption keys to make it difficult to identify the keys and decode messages.
- Authenticating that the data haven’t been altered as they pass through the mesh network.
- Changing the transmitted channel after each message is sent, making it hard to snoop at data.
- Requiring a physical connection to the instrument (via a HART hand-held) for the instrument join procedure.
Time to act
Vendor testing and end user trials have shown that WirelessHART provides the reliability, security and simplicity that the chemical industry demands from a wireless network. You can take advantage of the technology today to improve your vision of the process and to unlock valuable information hidden within existing instruments.
It’s clear that WirelessHART will complement not displace 4–20-mA loops. We’ve cited some applications, such as short-term diagnostic measurements, condition checking via adapters and instrument replacement, worth considering.
The WirelessHART specification is available now. Many significant instrument vendors (e.g., ABB, Emerson, Siemens and Yokogawa) are at an advanced stage of product development. Indeed, WirelessHART instruments and devices will start to reach the market in the middle of 2008 and the selection will widen during 2009.
Don’t wait. An open solution for an instrument wireless network is here. Find a local seminar to build you knowledge and identify the benefits a WirelessHART solution can provide for your process.
Gareth Johnston is wireless product manager for ABB, St. Neots, U.K. Alan Munns is product manager, refinery solutions, for ABB, St. Neots, U.K. E-mail them at firstname.lastname@example.org and email@example.com.