This unit enables existing wired HART field devices from any supplier to communicate with host applications by means of WirelessHART technology; it can also be installed on a non-smart (analog only) device and will transmit a digital representation of the analog 4-20 mA PV to the control room over the WirelessHART network. It is U.S.-rated Class I Zone 0,1 AEx 1/2 G ia d IIC, Class I Zone 2 AEx nL IIC, Class I Zone 20/21 AEx iaD 20 tD 21, with similar ratings for Canada, CENEC and IEC. The unit is installed permanently by wiring it directly to a standard HART field device, or connecting it anywhere on the 4-20 mA current loop. A wired HART field device retrofitted with the unit communicates its analog process variable over the existing wiring to the existing DCS with no wiring change. The unit simultaneously communicates the digital PV and device diagnostic information over the WirelessHART network. It can be loop- or line-powered, and up to eight devices can be multidropped to one adapter.