Endress+Hauser TMT84 iTEMP PROFIBUS PA Temp Transmitter

TMT84 iTEMP dual-input PROFIBUS PA temperature transmitter

The Endress+Hauser TMT84 is an iTEMP head transmitter built for PROFIBUS PA fieldbus networks. Unlike the analog TMT71 and the HART-based TMT72, it has two universal sensor inputs and no 4–20 mA output: it is powered from the bus and sends its readings digitally to a PROFIBUS DP/PA control system through a segment coupler. It fits in a form B terminal head (flat face) or in a field housing for Ex d applications, and it can be installed in Zone 1 hazardous areas as an intrinsically safe device. Seven Star LLC supplies the TMT84 in Oman and the GCC as an independent supplier in Muscat.

Two inputs let one device watch two sensors, form a mean or differential value, or provide redundancy. That is the main reason to choose the TMT84 for critical measuring points in a fieldbus plant, such as reactor, furnace and turbine temperatures.

Endress+Hauser TMT84 technical specifications

Two-channel functions of the TMT84

The second input is more than a duplicate channel. The transmitter offers sensor backup, which switches to sensor 2 when sensor 1 fails; a drift warning or alarm when the two readings move apart beyond a limit; temperature-dependent switching between sensors that cover different ranges; and mean or differential value calculation. A mean value with sensor redundancy keeps the signal continuous even when one probe fails. Because the inputs share no isolation, the two sensors should not introduce a ground loop; for example, use sensors with proper insulation or ungrounded junctions where possible.

The standard diagnostics include cable break, short circuit, corrosion of sensor leads per NAMUR NE89, wiring faults, internal faults and out-of-range detection of sensor and ambient temperature. Status messages follow the PROFIBUS PA profile 3.01/3.02 specification, and the condensed status makes alarms easy to interpret in the host.

TMT84 fieldbus integration, GSD files and bus address

The TMT84 talks as a slave on the PA segment, with up to 32 devices per segment in the architecture shown by the manufacturer. FISCO/FNICO conformity simplifies the design of intrinsically safe segments in explosive atmospheres. It can be addressed by software or DIP switches on the optional display and ships with address 126. GSD files are available both as manufacturer-specific (EH021551.gsd) and as profile GSDs (Pa139700 to Pa139703), plus bitmap files for the engineering tool.

If it replaces the previous iTEMP TMT184, the TMT84 recognises the configured device in the automation system and then reports with the TMT184 ID (1523 hex) for cyclic data. In this compatibility mode only profile 3.0 and one-channel operation are supported, and the software locking of the old model is not carried over.

Where the TMT84 fits and related iTEMP models

Use the TMT84 where the plant already runs PROFIBUS PA and each head transmitter should hand over data digitally. For analog loops, compare the TMT71 (4–20 mA only) and the TMT72 (4–20 mA with HART 7). Accessories named in the datasheet include the attachable TID10 display with bar graph and DIP switches, the TA30 field housings and DIN rail adapters, and configuration tools such as FieldCare (DTM) and SIMATIC PDM (EDD). Complete thermometer assemblies with Pt100 or thermocouple sensors from the same manufacturer pair directly with the TMT84.

TMT84 selection and ordering checklist

• One or two sensors and their types, wiring (2, 3 or 4 wire on input 1; limits apply on input 2) and ranges.
• Which two-channel function is needed: backup, drift detection, mean, differential or switching.
• Terminal version (screw or push-in) and whether ferrules will be used.
• Hazardous-area approval and field housing choice (TA30A, TA30D or the flameproof TA30H).
• PROFIBUS PA profile version, GSD requirement and the segment coupler or DP/PA link used.
• Whether a TID10 display is wanted, and the starting address.
• Quantity and tag list.

Installing and commissioning the TMT84

Install the transmitter on the insert in a form B head, connect the sensors to the numbered terminals and the bus cable to the bus connector; bus polarity is not important. Use twisted, shielded PA cable and follow the plant grounding scheme. When a display is fitted in a field housing, use a cover with a glass window. Set the address by DIP switch or software, load the GSD in the engineering station, and verify cyclic data and the condensed status before closing the cover.

For the measurement itself, enter the sensor coefficients if sensor-transmitter matching is required, and test the drift alarm threshold during a shutdown. Keep a spare head transmitter with the same address plan, and check the sensor-lead resistance at turnarounds since corrosion warnings appear before readings are corrupted.

TMT84 in Oman and GCC fieldbus plants

Large plants in Oman and the GCC, especially newer gas processing, power and petrochemical projects, use PROFIBUS PA to reduce cabling and to bring device diagnostics into the control system. The TMT84 suits critical temperature points on furnaces, reactors, turbine casings and large heat exchangers, where two sensors improve availability. Heat, vibration and dust are covered by the −40 to +85 °C range, the 5 g vibration rating and the IP66/67 field housings, and desalination and water-treatment skids benefit from the single-pair wiring.

Information to send with a TMT84 RFQ

• Sensor types, number of sensors and measuring ranges.
• Required two-channel function and diagnostics.
• Field housing or terminal head, plus Ex requirement.
• PROFIBUS PA host, profile version and address plan.
• Quantity and tags.

Documents and quotation

The Endress+Hauser Technical Information for the iTEMP TMT84 is attached on this page as a datasheet, with the input tables, bus data and housing dimensions summarised above.

Send the TMT84 part number, the sensor details and your PROFIBUS setup, and Seven Star LLC will confirm availability and delivery to Oman and the GCC.