A Comparison of WirelessHART and ISA100.11a

Overview:

The technology advancements in measurement instruments and final control elements provide greater process insight, reduce engineering costs and contribute to improving the overall operational performance of the plant. These instruments are often collectively referred to as smart devices. These smart devices include advanced diagnostics that can diagnose the health of the device and in many cases, the health of the process that the device is connected to. It is not uncommon for smart devices to include diagnostics that can detect plugged lines, burner flame instability, agitator loss, worn motor bearings, wet gas, orifice wear, leaks and cavitations. These devices tell the user how well they are operating and when they need maintenance. Many customers have reported substantial savings when using smart devices. Getting this technology to the field has often been hampered by the high cost of installation, as well as other factors. To address these needs what has emerged is a whole new line of devices using wireless technology. Although some of these devices contain the same technology as their wired counterparts, newer devices are emerging with innovative low-powered and/or mobile sensors. The most prominent wireless technology to-date uses IEEE 802.15.4-compatible DSSS radios and operates in the 2.4GHz ISM radio band (IEEE 802.15.4 supports multiple bands). Two standards using the IEEE 802.15.4 radio technology are IEC62591-1 (WirelessHART) and ANSI/ISA100.11a-2011 (ISA100.11a). The international standard, WirelessHART, and the U.S. standard, ISA100.11a, both provide full descriptions of the communication stacks. Although both standards contain many similarities, they also contain differences. This paper provides a brief overview of both standards, presents key differences between the standards and concludes with a discussion on applications and application integration.