A premium 18pt modbus thermocouple card designed for industrial applications and accuracy at long lengths. With class-leading resolution and accuracy and unmatched long-length thermocouple performance, this input card has been designed for users requiring a solution where data accuracy and integrity is key.


(Pricing listed in USD)

Additional information

Weight160 g
Dimensions12.3 × 10.4 × 2.2 cm
Power Supply Voltage

12-24 VDC

Required Power [Steady State]

30mA @ 24VDC

Thermocouple Input Voltage

1 VDC Max

Input Impedance

>1.2 MOhm

Data Output

RS485 Modbus RTU

Operating Temperature

-40°C to 85°C






4.85” / 123.19mm


4.09” / 103.89mm


0.87” / 22.10mm





Number Of Channels


Thermocouple Types

J, K, E, N, R, S, T, B


AWG 14-24


Class 1 Div 2 Groups CD T4


The GEOXTR-18 card uses Modbus over an RS485 connection. We recommend using FTDI’s USB to RS485 Cable to make this connection between PC and Card. The included TC18 Viewer Software will display and log thermocouple data, as well as allow for the GEOXTR-18 card to be configured. Other Modbus software will easily connect to the GEOXTR-18 card as well, including many SCADA systems.

In concept, a thermocouple wire is sensed with a miniscule amount of current. This results in a completely negligible voltage drop over even long distances. However, many TC Input card manufacturers design their cards with extra features and follow standard input protection schemes. These extra electronics introduce a small amount of leakage current onto the thermocouple which over long distances of 24 awg thermocouple result in voltage drops in the mV range, enough to drastically alter the temperature readings. As a result, many claim that 100ft is the maximum effective length of a thermocouple. Our GEOXTR-18 card however is designed to have as little leakage current as possible, while still maintaining the same features and protections expected of a TC Input Card. This enables us to maintain data accuracy at long lengths where others can deviate by over 20°C.

No, due to the use of premium components the GEOXTR-18 can work within its operating temperature range with nearly indistinguishable temperature error. This means that from season-to-season, or from day-to-night in extreme climates, temperature readings remain reliable. This is contrasted with many cards which struggle to exceed -10°C, and can experience dramatic temperature reading fluctuations based on shifting ambient temperature.

Included in the box is the GEOXTR-18 itself, a paper copy of our Quick look Guide, as well as a USB thumb drive with digital copies of the detailed User Manual, Quick Look Guide, and a copy of our TC18 software. Users must note that in order to connect to the TC18 software they must supply an RS485-USB cable which is not included.

The GEOXTR-18 comes with a detailed user manual that includes a comprehensive list of Modbus configuration settings and register map. For quick reference, the factory settings are:

Default Slave Address – 12
Default Comport Settings – Baudrate 19200, 8bit, No Parity, and 1 Stop Bit

While the GEOXTR-18 is applicable for a wide range of applications, it was designed from the ground up specifically for use in upstream oil and gas. Its Class 1 Div 2 certification and vastly superior -40°C to 85°C operating range means it is designed to perform in extreme environments. And from its design to its long-length capability to its industry-standard RS485 Modbus output, it has been engineered for safe and easy integration into oil & gas applications.

Want to know more?

One of our team members would be happy to help.