NTC Thermistor Transmitters
A thermistor transmitter converts a 10K NTC thermistor’s resistance into a 4-20 mA signal that a PLC, RTU or data acquisition input reads directly. The ROI-XMA is loop powered, 2-wire and DIN-rail mounted, in four standard temperature ranges – with wireless and USB versions when the reading needs to go somewhere else.
Choose by where the reading goes
Same 10K NTC thermistors, four ways to deliver the temperature – from one sensor to hundreds.
To a PLC or controller
ROI-XMA loop-powered transmitter for a spare 4-20 mA, 0-10 V or 1-5 V input. Four standard ranges.
See the ranges →No cable runs
ROI-RFX-10K reads 10K NTC thermistors and sends them wirelessly to a PC – up to about a mile with the right antenna.
Wireless temperature →Straight to a PC
ROI-USB-Thermistor: 4 thermistor channels, powered by the PC, software included.
USB thermistor recording →Many points, one cable
Thermistor transmitters and I/O nodes on a single RS-485 cable – 32 channels and more.
Multi-channel temperature →Ranges and prices
Pick the temperature span you need. Quantities, purchase orders and custom spans – request a quote.
| Range | Sensor | Output | Price | Order | Details |
|---|---|---|---|---|---|
| −10 to 50 °C | 10K NTC | 4-20 mA, 2-wire | $300 | Request a quote | View transmitter |
| 0 to 50 °C | 10K NTC | 4-20 mA, 2-wire | $300 | Request a quote | View transmitter |
| −10 to 75 °C | 10K NTC | 4-20 mA, 2-wire | $300 | Request a quote | View transmitter |
| 0 to 75 °C | 10K NTC | 4-20 mA, 2-wire | $300 | Request a quote | View transmitter |
| Other thermistors / custom span | 1K–100K NTC (e.g. 2.252K, 3K, 5K, 30K) | 4-20 mA, 2-wire | Quote | Request a quote | Built to order |
All four ranges on one page: 10K NTC to 4-20 mA transmitters · product listing: 10K NTC thermistor temperature transmitter.
Wireless and USB thermistor options
ROI-RFX-10K – wireless 10K NTC thermistor transmitter
ROI-USB-Thermistor – 4-channel USB thermistor recorder
| Product | Sensors | Output | Price | Order | Details |
|---|---|---|---|---|---|
| ROI-RFX-10K wireless thermistor transmitter a system uses at least 2 units | 10K NTC | 2.4 GHz wireless to a PC | $450 / unit | Request a quote | View product |
| ROI-USB-Thermistor recorder software included (download) | 4 × 10K NTC | USB to a Windows PC | $495 | Request a quote | View product |
| Multi-channel thermistor system | 10K NTC, 32+ points | Modbus RS-485 to PC / PLC | Quote | Request a quote | View system |
Thermistor signal conditioning, done for you
A thermistor is an accurate, low-cost temperature sensor, but its output is a changing, non-linear resistance – not a signal a standard PLC input can read. The ROI-XMA powers the thermistor, linearises its curve over the range you choose and drives a 4-20 mA current loop.
- Uses the spare analog input you already have – no special input card
- Two wires in, two wires out; thermistors have no polarity
- 4-20 mA runs long cable distances and flags a broken loop – why it starts at 4 mA
- Reads on 20 mA, 5 V and 10 V inputs: PLCs, RTUs and PC data acquisition
New to this? Thermistor wiring: how to connect a thermistor to a PLC · wiring diagram example.
Specifications – ROI-XMA
- Input
- 10K Ω NTC thermistor, 2-wire (1K–100K to order)
- Ranges
- 0 to 50 °C · −10 to 50 °C · 0 to 75 °C · −10 to 75 °C (custom to order)
- Output
- 4-20 mA, loop powered, 2-wire
- Loop supply
- 7.5 to 36 V DC, reverse-connection protected
- Response
- 10 ms, with output filtering
- Connections
- Pluggable Euro connectors, 30–12 AWG
- Mounting
- 35 mm DIN rail or surface, snap-on base
- Size
- 4.510 × 1.258 × 3.948 in (L × W × H above rail)
Voltage input? Add a loop termination resistor: 250 Ω gives 1-5 V, 500 Ω gives 2-10 V.
Where thermistor transmitters are used
HVAC
Supply, return and space temperature into building and plant controllers.
Refrigeration and chillers
Cold rooms, freezers and chilled water, where thermistors are most accurate.
Equipment and environment
Computer rooms, enclosures, environmental monitoring, dryers and other industrial processes.
Thermistor transmitters – common questions
What is a thermistor transmitter?
A signal conditioner that powers a thermistor, linearises its resistance curve and converts the temperature to a standard signal – here 4-20 mA – so a PLC or data acquisition input can read it.
Which thermistors does it work with?
The standard ranges are for 10K Ω NTC thermistors (10K at 25 °C). Transmitters for other NTC thermistors from 1K to 100K, such as 2.252K, 3K, 5K and 30K, are built to order with a custom span.
Can I read it on a 0-10 V or 1-5 V input?
Yes. Put a loop termination resistor across the input: 250 Ω gives 1-5 V and 500 Ω gives 2-10 V.
How far can the 4-20 mA signal run?
Long cable runs are normal for 4-20 mA. The limit depends on the loop supply voltage and the total loop resistance (wire plus input), within the 7.5 to 36 V DC supply range.
Can I monitor thermistors without running cable?
Yes. The ROI-RFX-10K wireless transmitter sends 10K NTC readings over 2.4 GHz to a PC, up to about a mile with the right antenna.
Related transmitters and guides
All 4-20 mA transmitters
Thermistor, RTD and potentiometer sensors into a PLC’s spare analog input.
4-20 mA transmitters →Potentiometer transmitters
Position feedback from 1K to 10K potentiometers to 4-20 mA.
Potentiometer transmitters →Need a thermistor on your PLC?
10K NTC to 4-20 mA transmitters in four standard ranges. Other thermistors, custom ranges and quantities on request – tell us the sensor, the range and what it connects to.
Questions? Contact us – we look forward to answering them.