What communication protocol does the TDXM-DC use?

The TDXM-DC is equipped with a built-in RS485 serial port operating as a Modbus RTU server, enabling direct communication with PLCs, SCADA systems, computers, and microcontrollers.

Is the TDXM-DC certified for hazardous area installations?

Yes. The TDXM-DC carries CSA Class I, Division 2, Groups C and D certification, making it suitable for use in environments where flammable gases or vapors may be present under abnormal conditions.

What is the scan rate of the TDXM-DC?

The TDXM-DC scans all 24 channels within 2 seconds, and any tripped set point is detected within two seconds of the threshold being exceeded.

Can the TDXM-DC monitor groups of temperatures and alarm on deviation?

Yes. The TDXM-DC supports Group Deviation (GRP/DEV) monitoring for up to two groups of temperatures, such as exhaust temperatures and bearing temperatures, alarming or shutting down when a channel deviates from the group average.

What type of display does the TDXM-DC use?

The TDXM-DC uses a custom 7-segment, 7-character backlit LCD with 1/2 inch (13 mm) characters. It clearly shows temperature readings, set point trip indications, and temperature units.

Temperature Scanner / Pyrometer

24-Channel Thermocouple Input | RS485 Modbus RTU | CSA Class I Div 2 Certified

Marine · Industrial · Oil & Gas

TDXM-DC Temperature Scanner / Pyrometer for Industrial Engine Monitoring

Name: TDXM-DC Temperature Scanner / Pyrometer
Brand: Murphy by Enovation Controls
SKU: TDXM-DC

The TDXM-DC Temperature Scanner / Pyrometer is a configurable, multi-channel thermocouple monitoring instrument designed for demanding industrial, marine, and oil & gas applications. Supporting up to 24 Type J or K thermocouple inputs, it provides real-time temperature scanning, programmable set point alarms, group deviation monitoring, and built-in RS485 Modbus RTU communication—all powered from a wide-range 10–32 VDC supply.

24Ch Thermocouple Inputs

2sec Full Scan Rate

RS485 Modbus RTU

CSA Cl I Div 2

Key Features

Configurable 24-Channel Thermocouple Scanning: The TDXM-DC accepts up to 24 Type J or K grounded or ungrounded thermocouples across individually configurable channels. Each channel can be set to its own thermocouple type and temperature unit (°F or °C), giving engineers precise, channel-level control over multi-zone temperature monitoring.
Three Independent Set Points per Channel: Each of the 24 channels supports three programmable set points — SP1, SP2, and SP3 — corresponding directly to three dedicated output circuits. This allows independent alarm thresholds to be assigned per channel, enabling tiered warning and shutdown responses within a single unit.
Group Deviation (GRP/DEV) Monitoring: A standout capability of the TDXM-DC is its ability to monitor up to two temperature groups and trigger alarms or shutdowns when any channel deviates beyond a defined range from the group average. This is particularly valuable for exhaust gas temperature balancing and bearing temperature monitoring on multi-cylinder engines.
Built-In RS485 Modbus RTU Communication: The integrated RS485 serial port operates as a Modbus RTU server, enabling direct interfacing with PLCs, SCADA systems, DCS platforms, and industrial computers. Baud rate, stop bits, and node address are all configurable via the front-panel keypad — no additional communication modules required.
Non-Volatile Set Point Trip History: The TDXM-DC stores the most recent set point trip for each output in non-volatile memory. After a shutdown event, engineers can quickly review which channel and set point triggered the fault — simplifying diagnostics and reducing post-event investigation time.
Backlit 7-Segment LCD with Membrane Keypad: The front panel features a large 7-character, 7-segment backlit LCD with clearly readable 1/2-inch (13 mm) characters. Navigation and configuration are handled through a five-button membrane keypad, allowing full setup without additional tools or software.
Open Thermocouple Detection: If any thermocouple becomes disconnected or fails open, the TDXM-DC automatically drives that channel's reading high. This forces a set point trip condition, preventing undetected sensor failures from masking a real thermal event.
CSA Class I, Division 2 Certified: The TDXM-DC carries CSA Class I, Division 2, Groups C and D third-party certification, confirming its suitability for installation in locations where flammable gases or vapors may be present under abnormal conditions — common in oil & gas and petrochemical facilities.

Applications

Engine Exhaust Temperature Monitoring: Monitors exhaust gas temperatures across multiple cylinders or turbocharger outlets simultaneously, helping detect misfires, fuel imbalances, or combustion anomalies before they escalate into engine damage.
Bearing and Mechanical Overheating Detection: Used in compressors, pumps, and rotating machinery to continuously track bearing temperatures. The group deviation feature triggers alerts when individual bearings exceed defined deviations from the average — an early warning of impending mechanical failure.
Gas Compression and Processing Plants: Deployed in gas compressor stations and processing facilities where multi-zone thermal management is essential. Enables simultaneous monitoring of process temperatures, cooler outlets, and equipment surfaces from a single instrument.
SCADA and PLC-Integrated Systems: Seamlessly integrates into Supervisory Control and Data Acquisition (SCADA) networks and PLC-based automation systems via the built-in RS485 Modbus RTU port, enabling centralized remote monitoring and data logging.
Marine Engine Room Temperature Management: Suitable for shipboard engine rooms where tracking thermal conditions across multiple engines, generators, and auxiliary equipment is required. Its wide operating temperature range and compact form factor make it ideal for harsh marine environments.
Oil & Gas Production and Drilling Equipment: Used on wellsite engines, natural gas engines, and production equipment in Division 2 classified hazardous areas where reliable thermocouple scanning and remote SCADA connectivity are required.

Technical Specifications

Precision thermocouple scanning with multi-channel configurability, industrial-grade communication, and third-party hazardous area certification for reliable performance in critical monitoring applications.

Parameter	Specification
Power Input	10–32 VDC, 4.2 W maximum
Thermocouple Inputs	Up to 24 channels; Type J or K, grounded or ungrounded (ungrounded recommended)
Set Points per Channel	3 adjustable set points (SP1, SP2, SP3) per channel
Outputs	Two (2) FET outputs: 0.5 A, 350 VDC, sink-to-ground on trip; One (1) Form-C Solid State Relay: 0.125 A, 350 VDC / 240 VAC (de-energized on trip)
Communications	RS485 Serial Port, Modbus RTU Server; configurable baud rate, stop bits, and node number
Sensor Scan Rate	All 24 channels scanned within 2 seconds
Measurement Range – Type K	0°F to 1999°F (0°C to 1093°C)
Measurement Range – Type J	0°F to 1538°F (0°C to 837°C)
Accuracy – Cold Junction	Better than ±1.0°F (±0.5°C)
Accuracy – Type J or K	±2°F (±1°C) over 100°F–1999°F (38°C–1093°C)
Cold Junction Compensation	-40°F to 185°F (-40°C to 85°C)
Display	7-segment, 7-character backlit LCD; 1/2 in (13 mm) character height; shows temperature, units, and set point trip indication
Operating / Storage Temperature	-40°F to 185°F (-40°C to 85°C)
Open Thermocouple Detection	Drives channel reading high on open sensor condition
Set Point History	Last trip per output stored in non-volatile memory
Group Deviation Monitoring	Up to 2 temperature groups; alarms or shuts down on deviation from group average
Third-Party Approvals	CSA Class I, Division 2, Groups C and D
Dimensions (H × W × D)	5.2 in × 6.8 in × 2.2 in (133.3 mm × 172.9 mm × 55.9 mm)
Shipping Weight	Approx. 2 lb (0.93 kg)
Shipping Dimensions	5.5 × 9 × 9.5 in (140 × 229 × 241 mm)
Optional Accessories	RS485 to USB interface kit with 10-inch cable (Part No. 53702325); MConfig™ configuration software (free download)

How the TDXM-DC Temperature Scanner / Pyrometer Works

The TDXM-DC continuously scans all configured thermocouple channels in a two-second cycle, reading live temperature data from up to 24 Type J or K sensors connected via screw-terminal pairs. Each channel is evaluated independently against its three programmed set points — SP1, SP2, and SP3 — which map directly to the unit's three output circuits. When a channel's temperature crosses a set point threshold, the corresponding FET or Form-C relay output activates within the same scan cycle, triggering downstream alarms, shutdown circuits, or control actions.

The Group Deviation (GRP/DEV) function adds a layer of comparative intelligence: the instrument calculates a running average across designated channel groups — such as all exhaust cylinders or all bearing sensors — and flags any individual reading that strays beyond the configured deviation limit. This approach catches gradual performance degradation that fixed-threshold monitoring alone might miss.

All configuration — including thermocouple type selection, set point values, baud rate, and RTU node address — is performed through the front-panel five-button membrane keypad using a guided menu system. For larger deployments or fleet-wide configuration, the optional MConfig™ software and RS485-to-USB kit allow programming and data retrieval from a connected PC, while the Modbus RTU server enables ongoing data integration with SCADA and PLC platforms in real time.

Technical FAQ

Common Questions Answered

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The TDXM-DC supports up to 24 Type J or K thermocouple channels, each individually configurable for temperature unit, set point values, and alarm behavior. Unused channels can be set to Ignore so they do not appear in the display or generate any fault trip conditions.

The TDXM-DC is equipped with a built-in RS485 serial port configured as a Modbus RTU server. This allows it to communicate directly with PLCs, SCADA systems, DCS platforms, and industrial computers. The baud rate, stop bits, and RTU node number are all configurable from the front-panel keypad.

Yes. The TDXM-DC carries CSA Class I, Division 2, Groups C and D certification. This qualifies it for use in environments where flammable gases or vapors may be present under abnormal conditions, including oil & gas production, compressor stations, and petrochemical facilities. For outdoor installations, it should be mounted in a suitable weatherproof enclosure.

The Group Deviation (GRP/DEV) function monitors up to two groups of temperature channels and triggers an alarm or shutdown if any individual channel deviates beyond a set range from the group's running average. This is particularly useful for engine exhaust temperature balancing and bearing condition monitoring, where a rising deviation — rather than an absolute threshold — is the first sign of developing trouble.

Ungrounded thermocouples are recommended for use with the TDXM-DC. When grounded thermocouples are used, differences in grounding potential between devices can introduce reading errors. Using ungrounded sensors eliminates this source of interference and ensures the highest measurement accuracy across all 24 channels.

Yes. The optional RS485-to-USB interface kit (Part No. 53702325) connects the TDXM-DC to a Windows PC, and the free MConfig™ configuration software allows engineers to configure all parameters, review set point history, and manage channel assignments from a computer — streamlining setup for complex or multi-unit deployments.