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.

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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.)


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Data Loggers

Compatible Note

Listed Under

Common Accessory for the following products: