Emerson Wireless 775 THUM™ Adapter

The 775 THUM Adapter retrofits onto almost any existing 2-, 3-, or 4-wire HART® device (HART 5.0 or newer) to make it wireless. It transmits HART measurement and diagnostic data over a self-organizing WirelessHART® (IEC 62591) network with greater than 99% data reliability, bringing new visibility to previously inaccessible or hard-to-reach measurement points.

The THUM Adapter works with almost any 2-wire, 3-wire, or 4-wire HART device running HART 5.0 or newer. This includes Rosemount™ pressure, level, temperature, and flow transmitters, as well as HART control valve positioners. The THUM Adapter scavenges power from the HART loop, and device compatability depends on the loop meeting minimum voltage and resistance requirements. Examples for compatible transmitters include the Rosemount 3051S Pressure Transmitter and Micro Motion Coriolis Meter.

Yes. The 775 THUM Adapter is available with intrinsic safety certifications for installations in classified hazardous areas globally. Approval options include ATEX, IECEx, FM (USA and Canada Intrinsically Safe/Non-incendive), INMETRO (Brazil), CML (Japan), KOSHA (Korea), and EAC (Customs Union) certifications.

No battery is required. The THUM Adapter uses SmartPower™ power-scavenging technology, drawing operating power directly from the existing 4–20 mA HART loop. The minimum loop load is 250 ohms, and the adapter causes only a small, non-disruptive voltage drop (linear from about 2.25 V at 3.5 mA to 1.2 V at 25 mA).

The update rate is user-selectable from 8 seconds to 60 minutes. The THUM adapter uses an integral omnidirectional antenna operating on IEC 62591 WirelessHART at 2.4 GHz. Effective communication depends on the installation environment and network layout. For best performance, mount the 775 vertically and approximately 3 feet from large structures or conductive surfaces. Where surrounding infrastructure limits signal, the adapter can be remote mounted from the wired device. Since WirelessHART is a self-organizing mesh, adding devices to the network increases available communication paths.

It can be mounted directly to the conduit of the wired HART device (½–14 NPT or M20 conduit adapter) or installed remotely using an aluminum or stainless-steel remote mount kit when direct mounting isn’t practical (e.g., high-vibration equipment). For best wireless performance, Emerson recommends vertical orientation and at least 3 feet of clearance from large metal structures.

For wiring guidance, reference the online SmartWireless THUM adapter Wiring tool. (link: https://www3.emersonprocess.com/rosemount/thumwiringwebapps/default.aspx)

Yes. The THUM Adapter connects to your control system transparently through a WirelessHART gateway using standard industry protocols (including HART-IP, Modbus, OPC). For HART Revision 7 or later wired devices integrated via Native I/O (HART-IP) into DeltaV™ or Ovation™, the THUM must be reconfigured from its factory-default HART Command 3 to Command 9 to prevent intermittent good/bad status flipping.

The THUM adapter transmits the HART information from the connected device into the WirelessHART network, making it available at the Gateway alongside the existing 4-20 mA signal. This includes the device's HART tag, dynamic process variables, and device status. The specific available data depends on the connected device and what it supports.

The THUM can be used anywhere a wired HART device exists but running new wiring is costly or impractical. Example applications include wireless tank gauging (pairing with a Tank Hub for tank level, temperature, and pressure data), flow measurements for heat exchanger monitoring, continuous emissions monitoring, and remote flame detection.