CS215-L Temperature and Relative Humidity Probe
Competitively Priced; SDI-12 Output
General-purpose temperature and RH probe
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The CS215 is a temperature and relative humidity probe that uses a Swiss-made digital humidity and temperature element that makes accurate and stable measurements. The element is based on Sensirion's CMOSens technology, which has been tested for more than two years in alpine conditions. The CS215 outputs an SDI-12 signal that is measurable by most Campbell Scientific dataloggers.

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Benefits and Features

  • Accurate and stable measurements
  • Field changeable element allows on-site recalibration
  • Each sensor element is individually calibrated so no further adjustment of the probe is required
  • Low power consumption
  • Digital SDI-12 output
  • Wide operating range

The "-L" on a product model indicates that the cable length is specified at the time of order.


CS215-L probe
CS215-L probe
CS215-L probe
CS215-L probe mounted with a 10-plate shield (non-probe items sold separately)
CS215-L probe mounted with a 6-plate shield (non-probe items sold separately)
CS215-L probe mounted with a 6-plate shield (non-probe items sold separately)

Detailed Description

The CS215 uses the Sensirion SHT75, a combined relative humidity and temperature element, to provide accurate, stable measurements. The Sensirion SHT75 element is field-replaceable, eliminating the downtime typically required for the recalibration process. The CS215 outputs an SDI-12 signal that's measurable by many Campbell Scientific dataloggers.

The CS215 should be housed in a solar radiation shield—typically the 41303-5A. The 41303-5A 6-plate naturally aspirated shield attaches to a mast, crossarm, or tower leg.


Sensing Element Sensirion SHT75
Communication Standard SDI-12 V1.3 (responds to a subset of commands)
Housing Material Anodized aluminum
Housing Classification IP65 (NEMA 4)
Sensor Protection Outer glass-filled polypropylene cap. Inner expanded PTFE filter. Filter material has a porosity of 64% and a pore size of < 3μm.
Supply Voltage
  • The supply voltage is typically powered by the datalogger's 12 V supply.
  • 7 to 28 Vdc (for serial numbers E13405 and newer)
  • 6 to 18 Vdc (for older models)
Typical Current Drain
  • 120 μA (quiescent)
  • 1.7 mA (measurement takes 0.7 s)
EMC Compliance Tested and conforms to IEC61326:2002.
Operating Temperature Range -40° to +70°C
  • 1.2 cm (0.5 in.) at sensor tip
  • 1.8 cm (0.7 in.) at cable end
Length 18.0 cm (7.1 in.) including strain relief
Weight 150 g (5.3 oz) with 3.05-m (10-ft) cable

Relative Humidity

Measurement Range 0 to 100% RH (-20° to +60°C)
Output Resolution 0.03% RH
  • ±2% (10% to 90% range) at 25°C
  • ±4% (0% to 100% range) at 25°C
Short-Term Hysteresis < 1% RH
Temperature Dependence Better than ±2% (-20° to +60°C)
Typical Stability ±1.0% per year
Response Time with Filter < 20 s (63% response time in still air)
Calibration Traceability NIST and NPL standards

Air Temperature

Measurement Range -40° to +70°C
Output Resolution 0.01°C
  • ±0.3°C (at 25°C)
  • ±0.4°C (5° to 40°C)
  • ±0.9°C (-40° to +70°C)
Response Time with Filter < 120 s (63% response time in air moving at 1 m s-1)


Sensor Mounts

When exposed to sunlight, the CS215 must be housed in a 41303-5A radiation shield. To attach the 41303-5A to a CM202, CM204, or CM206 crossarm, place the 41303-5A’s U-bolt in the bottom holes. To attach the radiation shield directly to a tripod mast, tower mast, or tower leg, place the U-bolt in the side holes.

The CS215-L Temperature and RH sensor can also be housed in the 43502 if a special adapter from R. M. Young (R. M. Young pn 43537) is used.

Datalogger Considerations

Compatible Contemporary Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR6 CR9000X

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR9000 CR5000 CR7X

Frequently Asked Questions

Number of FAQs related to CS215-L: 14

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  1. If the values are not within the published range of the sensor, there are several things to check:

    1. If the yellow cap has not already been removed, remove it.
    2. Verify that the program is correct without additional multipliers or offsets.
    3. Ensure that the filter and radiation shield are clean so that air can freely flow into and past the sensor.
    4. If the first value returned in the array is NAN, this is usually an indication that the datalogger is unable to communicate with the sensor. This could be caused by a power issue, an incorrect SDI-12 address, one or more disconnected wires, or a broken sensor. 
  2. If the -100 is actually -99.999 for both temperature and RH, this is an indication of what should be a rare condition. This indicates that the microprocessor in the body of the probe cannot communicate with the sensor element correctly. To be more specific, the communication between the microprocessor and the sensor element includes a CRC check. The microprocessor tries up to three times to get data with a good CRC. If it does not succeed, its sets both values to -99.999.

    The following are some reasons why this might happen, as well as some suggested solutions:

    • There is a source of very strong RF interference near the tip of the probe. Check that the probe is not mounted close to a cellular telephone or radios.
    • The sensor element does not have a good connection with its socket, or the socket is corroded. Remove the cap of the sensor, and inspect or reseat the sensor element.
    • The sensor element is faulty. A replacement element can be ordered from the Sensirion website.
    • There is an internal connection issue or dry solder joint inside the sensor body. In 2011, some sealing glue ran down inside the probe’s body into a connector, which caused a poor, intermittent connection. Measures were taken to prevent this from happening in CS215-L sensors produced later.
  3. Relative humidity (RH) from the probe is capped at 100%. If readings of 100% occur during drier conditions, it is possible that the chip, the entire sensor, or both have associated issues. Repair, maintenance, or replacement is likely needed. Contact Campbell Scientific for assistance.

  4. Yes, using pn 18144Replacement RH and Temperature Element and Filter Cap for CS215. However, Campbell Scientific recommends taking the necessary precautions associated with changing electronics in the field. As this is a relatively small chip, it is not recommended to replace the chip during stormy weather or without having some type of collection container placed underneath in case the chip is accidentally dropped.

    For assistance replacing the chip, refer to the “Maintenance and Calibration” section of the instruction manual.

  5. Refer to the “Maintenance and Calibration” section of the instruction manual.

  6. Yes. This can be purchased from Campbell Scientific (pn 18144, Replacement RH and Temperature Element and Filter Cap for CS215). This chip replaces both the temperature and RH humidity sensing element.

  7. No. The sensor cannot be calibrated, but Campbell Scientific can perform a calibration verification that includes multiple points (temperature and relative humidity). Campbell Scientific recommends using three points for RH (10%, 50%, and 90%) at one temperature (25 degrees Celsius), as well as an additional temperature point. This verification process has an initial setup charge and an additional per-point charge. Campbell Scientific sends a document indicating the values tested to with the accompanying measurement from the associated sensor.

  8. The most significant difference is that the CS215-L has an SDI-12 output and that the HMP60-L has a voltage output. Additional differences are outlined in the “Air Temperature & Relative Humidity” brochure, which compares all of the Campbell Scientific temperature and relative humidity sensors. 

  9. Not every sensor has different cable termination options. The options available for a particular sensor can be checked by looking in two places in the Ordering information area of the sensor product page:

    • Model number
    • Cable Termination Options list

    If a sensor is offered in an –ET, –ETM, –LC, –LQ, or –QD version, that option’s availability is reflected in the sensor model number. For example, the 034B is offered as the 034B-ET, 034B-ETM, 034B-LC, 034B-LQ, and 034B-QD.

    All of the other cable termination options, if available, are listed on the Ordering information area of the sensor product page under “Cable Termination Options.” For example, the 034B-L Wind Set is offered with the –CWS, –PT, and –PW options, as shown in the Ordering information area of the 034B-L product page.

    Note: As newer products are added to our inventory, typically, we will list multiple cable termination options under a single sensor model rather than creating multiple model numbers. For example, the HC2S3-L has a –C cable termination option for connecting it to a CS110 instead of offering an HC2S3-LC model. 

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