Overview

EQXTC06 Datasheet

6-Channel K-Thermocouple Sensor Expansion Module for the EQSP32 Micro PLC.

Version 1.1Revision 102026
EQXTC06 6-channel thermocouple input expansion module for the EQSP32 PLC in a DIN-rail enclosure

Overview

The EQXTC06 is a six-channel thermocouple expansion module for the EQSP32 Micro-PLC IoT controller, designed for precise temperature measurements in industrial applications.

Supporting K-type thermocouples, each module sequentially processes and updates all of its six channels. With up to 15 cascaded modules, a single EQSP32 may be equipped with up to 90 thermocouple sensors without adding to the system’s processing time.

The processed temperature data is automatically requested by the EQSP32 controller and made available locally, as if it were a native EQSP32 peripheral.

It incorporates ESD protection, integrated cold-junction compensation, and a high-resolution 14-bit signed conversion, delivering a nominal temperature resolution of 0.25°C.

With its integrated fault detection capabilities, reliable operation is ensured by quickly highlighting and addressing potential wiring issues. The fault detection includes identifying thermocouple shorts to GND or VCC as well as open sensor connections.

It is housed in a space-efficient DIN-rail mountable enclosure, tailored for easy installation and organized wiring within control cabinets. Its design includes high-quality screw terminals, ensuring secure and reliable connections for thermocouple sensors, minimizing the risk of disconnections in industrial settings.

Designed for industrial environments, the module operates reliably in temperatures ranging from –20 °C to +55 °C and features IP20 protection.

The EQXTC06 is automatically detected by the EQSP32 upon power-up, functioning seamlessly as a native peripheral. Powered directly through the EQSP32’s board-to-board connector, it eliminates the need for additional power supplies. This plug-and-play capability simplifies setup, enabling users to expand their systems with minimal effort or configuration.

Firmware updates are easily applied through its front-facing USB-C port, ensuring quick access to the latest features and improvements. This update mechanism minimizes downtime and maintains optimal functionality without removing the module from the system. The front-facing LEDs provide visual indicators for power and operational status, for easy assessment of the module’s state.

The EQXTC06 is supported by the EQ-AI generative AI model, simplifying programming and integration by assisting in code generation. This innovative approach reduces complexity and accelerates deployment, making advanced industrial solutions accessible to users with varying technical expertise.

Key Features

  • Six-channel support for K-type thermocouples
  • High-resolution 14-bit signed conversion with 0.25°C nominal temperature resolution
  • Integrated cold-junction compensation for precise ambient temperature adjustment
  • Fault detection for shorts to GND, VCC, and open thermocouple connections
  • ESD protection up to ±2kV (Human Body Model)
  • Compact DIN-rail mountable design for organized installation
  • Automatic detection by EQSP32
  • LED indicators for power and status monitoring
  • Front-facing USB-C port for convenient firmware updates
  • Powered directly by EQSP32, no external power supply required
  • Simplified integration with EQ-AI generative AI for easy code generation
  • Compact, 2SU-wide (36 mm), DIN-rail mount enclosure with 12 screw terminals
  • –20 °C to +55 °C operating ambient temperature
  • IP20-rated enclosure

Applications

  • Industrial temperature monitoring.
  • Process control systems.
  • HVAC system management.
  • Furnace and oven control.
  • Food and beverage processing.
  • Plastic and rubber manufacturing.
  • Pharmaceutical production.
  • Energy and utility monitoring.
  • Oil and gas operations.
  • Environmental monitoring.
  • Textile industry processes.
  • Cold chain logistics.
  • Building automation systems.
  • Aerospace testing.
  • Brewing and distillation.
  • Waste management systems.

Ordering Information

Part numberDescriptionInputsEnclosure
EQXTC066 Channel K-Thermocouple Sensor Expansion Module for EQSP326 × K-type thermocouple2SU (36 mm) DIN-rail, IP20

Product page and ordering: erqos.com/product/eqxtc06

Block Diagram

EQXTC06 block diagram: 6 thermocouple inputs with ESD protection, compensation, fault detection and EQSP32 bus
Figure 1: EQXTC06 block diagram

System Specifications

Section / Features
Power Management
Supplied by the board-to-board connector
Thermocouple Inputs
6 x K-type thermocouple sensor inputs
Measuring range –200 °C to +1350 °C
14-bit signed temperature readings with 0.25°C nominal temperature resolution
Integrated cold-junction compensation
ESD protection up to ±2kV (Human Body Model)
Shorted sensor to GND or VCC, and open sensor
Indications
Green LED for power indication
Red LED for device status
Enclosure
Easy standard DIN rail push-fit mounting with spring mechanism
IP20
Expandability
Push-fit expansion module mounting
Automatic module detection and characterization
Firmware Update
Front-facing USB-C for easy firmware upgrades
Environment
–20 °C to +55 °C

Electrical Specifications

Absolute Maximum Ratings

PinTypeMin.Typ.Max.Unit
T+, T- to GNDAnalog Input-0.3—3.6V
T+, T- ESD (Human Body Model)Analog Input-2000—2000V

Connecting EQXTC

To use the EQXTC thermocouple sensor expansion module, mount it next to the EQSP32 controller on the DIN rail and simply slide it until the board-to-board connector is fully inserted into EQSP32.

The expansion module is powered by the board-to-board connector and does not require an external power supply.

When adding additional modules, it is recommended that the power is disconnected from the system. After adding the expansion modules and powering up the system, EQSP32 will start the automatic detection and indexing process.

For safety and ease of use, it is strongly recommended that a main circuit breaker is used to completely isolate the AC/DC from the grid.

EQXTC06 thermocouple input module sliding onto an EQSP32 PLC on a DIN rail, with breaker and 24 V DC supply
Figure 2: Slide EQXTC to connect on EQSP32
EQXTC06 thermocouple expansion module mounted next to an EQSP32 PLC on a DIN rail
Figure 3: Connected EQXTC on EQSP32

Warning

Make sure that the appropriate ground fault circuit breaker, fuses or circuit breakers and any other necessary protective components are used if there is any risk of user electrocution.

Visual Indications

EQXTC06 front panel with green power LED, red status LED and Boot button for firmware updates
Figure 4: Front panel: LEDs and Boot button

When the module is connected and the system is powered on, the POWER LED should light up solid green.

If the STATUS LED is solid red after the automatic detection, it means that the EQXTC module has encountered a communication issue.

During data exchange between the main EQSP32 unit and the EQXTC module, the STATUS LED will be flashing for each transaction.

Power LED (green)

OnPowered on
OffNo power

Status LED (red)

OffNo errors, no communication
Fast FlashingData exchange
OnCommunication error

Pinout

EQXTC06 pinout: X1 with thermocouples TC1–TC3, X2 with TC4–TC6, USB-C port, LEDs and Boot button
Figure 5: EQXTC06 terminals and front panel
X1
Screw terminal connector 1
USB-C
Firmware update port
X2
Screw terminal connector 2

X1 – Screw Terminal Connector 1

The X1 connector provides wiring connections for thermocouple sensors’ channels 1, 2, and 3, marked as TC1, TC2 and TC3 respectively.

EQXTC06 X1 screw terminal: thermocouple inputs TC1–TC3 (T+ and T− pairs)
Figure 6: X1 terminals
NamePinFunctionType
X1T1+, T2+, T3+Positive thermocouple terminal (+)ANALOG IN
T1-, T2-, T3-Negative thermocouple terminal (-)ANALOG IN

X2 – Screw Terminal Connector 2

The X2 connector provides wiring connections for thermocouple sensors’ channels 4, 5, and 6, marked as TC4, TC5 and TC6 respectively.

EQXTC06 X2 screw terminal: thermocouple inputs TC4–TC6 (T+ and T− pairs)
Figure 7: X2 terminals
NamePinFunctionType
X2T4+, T5+, T6+Positive thermocouple terminal (+)ANALOG IN
T4-, T5-, T6-Negative thermocouple terminal (-)ANALOG IN

Power Distribution

EQXTC’s core and peripherals are powered by EQSP32’s power management unit via the board-to-board connector.
The board-to-board connector carries the power lines for system operation and the communication bus for allowing the expansion modules to interact with the main EQSP32 unit.

EQXTC’s control unit may also be powered by the front-facing USB-C port. By connecting the thermocouple sensor expansion module via the USB-C port, the system’s core will be powered on. This allows for easy firmware update without being connected to the EQSP32 or any external power supply.

EQXTC06 power distribution: 5 V, GND and bus from the EQSP32 expansion connector, USB-C for firmware updates
Figure 8: Power distribution

Mechanical Dimensions

All dimensions are measured in mm with a +/-0.1 tolerance.

EQXTC06 dimensions: DIN-rail enclosure 36.3 × 90.2 × 52.5 mm, 5.08 mm terminal pitch
Figure 9: Mechanical dimensions: side and front views
EQXTC06 DIN-rail enclosure 3D view with screw terminals, USB-C port, LED windows and expansion connector
Figure 10: Mechanical dimensions: 3D view

Thermocouple Sensor Inputs

Equivalent Thermocouple Conditioning and Measurement Circuit

EQXTC06 thermocouple input equivalent circuit: T+ and T− through ESD protection to amplifier and fault detection
Figure 11: Equivalent Thermocouple Input Circuit

Thermocouple Wiring

The thermocouple sensor provides precise temperature measurement by utilizing the voltage generated at the thermocouple junction.

Each thermocouple channel includes two terminals (T+ and T-) for connecting the thermocouple wires. The EQXTC amplifies and measures the voltage generated at the junction to determine the temperature.

Additionally, the module measures the ambient temperature to apply cold-junction compensation, ensuring accurate readings regardless of external temperature variations.

EQXTC06 wiring: Type K thermocouple + lead to T+ and − lead to T−
Figure 12: Thermocouple wiring example

Readings and Fault Codes

eqsp32.readPin( EQXTC(ii, nn) ) returns the temperature of channel nn in °C × 10; for example, 253 corresponds to 25.3 °C. Channel 7 returns the internal (cold-junction) temperature of the module in the same unit.

If the module detects a thermocouple fault on a channel, readPin() returns a fault code instead of a temperature: TC_FAULT_OPEN (open thermocouple), TC_FAULT_SHORT_GND (thermocouple shorted to GND) or TC_FAULT_SHORT_VCC (thermocouple shorted to VCC). Several faults at once give a combined code; any value of 0x8000 (32768) or more is a fault code. The channel returns to the temperature as soon as the fault is gone.

A module that is not connected reads 0 (0.0 °C) on all channels. Use eqsp32.isModuleDetected( EQXTC(ii) ) to tell a disconnected module from a reading of 0.0 °C.

Library Reference
Usage
eqsp32.readPin( EQXTC(ii, nn) )

Returns the temperature in °C × 10 (253 for 25.3 °C), or a fault code (0x8000 or more, see Readings and Fault Codes)

ii: number (index) of EQXTC module on the chain (*)

nn: EQXTC channel number (1 to 6 for thermocouple channels, 7 for the module’s internal temperature)

(*) For 2 EQXTC modules connected on the main unit, the first one (closer to the main unit) will have an index of 1, the second EQXTC index of 2 etc.
The index refers only to the same type of modules. Different types of modules will be indexed with their own type.

Boot Button & Firmware Update

Boot Button

The Boot button is only used for entering the EQXTC module into firmware update mode (or maintenance mode). To enter maintenance mode, keep the Boot button pressed while powering up the module.

Another option is to keep the Boot button pressed while sending a reset command to the module via the serial terminal (!RST=1, 115200 baud).

Once the module is in maintenance mode, it will be shown as a storage device. Drag and drop the desired .uf2 firmware file into the RPI-RP2 storage device and the update will be performed automatically.

Once the update is done, the unit will be automatically rebooted.

Power cycle the system to trigger the automatic detection procedure and the system will be ready for normal operation.

Notices

Erqos Technologies P.C. may change products, specifications and this document at any time without notice. Always use the latest revision, available at erqos.com.

These products and this document are intended for qualified professionals. The information in this document is provided as is. Erqos Technologies P.C. assumes no liability for its use. Customers are responsible for designing and testing their own applications, including the protection of connected equipment and persons.

Revision History

VersionRevisionDateStatusChanges
v1.1Rev10202620 Oct 2026ReleasedUpdated the temperature format; added the measuring range and fault codes.
v1.0Rev10192619 Oct 2026ReleasedFirst released version.

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