CS250DM Pt-1000 Class A, Precision Air Temperature Sensor with Digital Modbus RS-485 Output


The CS250DM is a Pt-1000 Class-A air temperature sensor for temperature gradient and stability analysis. This sensor delivers extremely accurate and precise air temperature data that is necessary for IEC 61724 Class-A solar monitoring applications and Delta Temperature (ΔT) calculations. It also includes a digital Modbus RS-485 output, ensuring data quality over long cable lengths.

Read More

Benefits and Features

  • High accuracy and precision
  • Exceeds IEC 61724-1 standards for ambient air temperature measurements
  • Exceeds EPA standards for ΔT measurements
  • Digital Modbus RS-485 output ensuring data quality over long cable lengths
  • Best-in-class noise protection and isolation meet IEC Class 4 standards
  • NIST-traceable, serialized calibration certificate supplied with every sensor


CS250DM sensor
CS250DM sensor
CS250DM sensor
CS250DM sensor with Ships With items

Detailed Description

The CS250DM uses a precision Pt-1000 Class A platinum resistor thermometer (PRT) to provide the highest level of accuracy. The cable includes a Campbell Scientific precision analog-to-digital, smart-sensor module for making the measurements. The module design is optimized for the class A PRT that minimizes self-heating and lead-wire resistance. Measurement electronics are surge protected with 1200 V isolation and environmentally protected with a rugged overmolding with an IP65 rating.

When exposed to sunlight, the CS250DM should be housed in the RAD06 6-plate radiation shield.


Measurement Uncertainty ±0.3°C
Element Stem Material 316L stainless steel sheathed
Surge Protection 1200 V isolation
Supply Voltage 5 to 30 Vdc
Power Draw 15 mA
Temperature Coefficient TCR = 3850 ppm/K
Stem Diameter 0.32 cm (0.125 in.)
Overall Stem Length 6.35 cm (2.5 in>0
Sensor Dimensions 17.15 x 11.13 x 6.05 cm (6.75 x 4.38 x 2.38 in.)
Sensor Weight 90.7 g (0.2 lb)

Sensing Element

Precision 1000 ohm Class A platinum (Pt 1000)
Accuracy ±(0.15 + 0.002T)°C
Long-Term Stability Maximum Ro drift = 0.04% after 1000 hours at 400°C
Measurement Temperature Range –75° to +250°C
Time Constant 15 seconds in 5 m/s wind


Protocol Modbus RTU protocol (over RS-485)
Format 8 data bits, 1 stop bit, even parity as default (user-configurable)
Baud Rate 19,200 bps as default (user-configurable)
Modbus ID Last two digits of serial number as default (user-configurable)

Cable (Sensor Head to DM Board)

Wire Size and Type 24 AWG (7/32,RT38) copper
Insulation Type PFA insulated (Teflon®)
Insulation Rating –75° to +250°C
Sheath Thin PFA sheathed overall
Number of Cores 3
Physical Properties Good abrasion and moisture resistance
Overall Diameter 2.1 mm (0.08 in.)

Cable (DM Board to PT)

Wire Size and Type 24 AWG (7/32) tinned copper
Insulation Type PVC
UL AWM 10012 1000V 105°C
Filler Fibrillated polypropylene as required for uniform round construction
Drain 24 AWG (7/32) tinned copper (cabled, touching foil)
Shield Aluminum/Mylar (100% coverage, 25% minimum overlap, foil facing in)
Nominal Wire Diameter 0.61 mm (0.024 in.)


Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.

Data Loggers

Product Compatible Note


CS250DM Example Program v.1 (1 KB) 12-07-2020

The example CR6 program measures four CS250DM sensors, averages the four temperature measurements, and calculates the standard deviation of the four sensors.

Listed Under

Common Accessory for the following products:

Privacy Policy Update

We've updated our privacy policy.  Learn More

Cookie Consent

Update your cookie preferences.  Update Cookie Preferences