Chapter 3Chapter 3

Wireless Field Devices

Wireless Devices - Process IndustryWireless Devices - Process IndustryWireless Devices - Process IndustryWireless Devices - Process Industry Most wireless field devices designed for use

in the process industry are based on either the international WirelessHART standard IEC 62591, or the ISA100.11a national standard.

All products claiming HART Protocol compliance must be independently tested and verified by the HART Communication Foundation. Devices that pass this testing and are registered may display the logo.

The ISA100 Wireless Compliance Institute (WCI) has been established by ISA to certify device conformance to the ISA100.11a standard. Successfully passing the WDI conformance test is the basis for using the ISA100 Wireless Compliant logo and registration.

Certified Wireless Devices Certified Wireless Devices Certified Wireless Devices Certified Wireless Devices WirelessHART

ISA100

Battery ReplacementBattery Replacement The power modules used in

wireless devices are designed to be periodically replaced as illustrated in Figure 3-3. The power module used in some devices is designed to be intrinsically safe, which allows field replacements without the need to remove the transmitter from the process.

The lithium-thionyl chloride battery cells used by many wireless devices provide high energy density, long shelf life and a wide working temperature range.

Example – Wireless Pressure and Example – Wireless Pressure and Temperature Transmitter Temperature Transmitter Example – Wireless Pressure and Example – Wireless Pressure and Temperature Transmitter Temperature Transmitter

The communication update rate that is configured for a device has a direct impact on the expected battery life, as does the service temperature.

In most cases, the communication update rate may be selected by the end user. Typical examples of how update rate and operating temperature impact battery life are shown.

Using an Adapter to Access Device Using an Adapter to Access Device Diagnostics and MeasurementDiagnostics and MeasurementUsing an Adapter to Access Device Using an Adapter to Access Device Diagnostics and MeasurementDiagnostics and Measurement

WirelessHART adapters and ISA100 adapters have been developed that access and wirelessly communicate diagnostic information. Such adapters use power drawn from the wired transmitter current loop.

An adapter can also be installed on a traditional wired transmitter for wireless access to the measurement values of devices used for monitoring or control. This approach may be especially useful when working with an existing wired transmitter or when installing new four wire transmitters that have a local source of power.