CS511-L Dissolved Oxygen Sensor
Widely Compatible
Submersible, rugged, low-maintenance DO sensor
weather applications water applications energy applications gas flux and turbulence applications infrastructure applications soil applications


The CS511, manufactured by Sensorex, is a submersible, rugged, low-maintenance sensor that senses dissolved oxygen in a medium (typically water). It consists of a self-polarizing galvanic cell that generates a millivolt signal proportional to the amount of oxygen present in the measured medium (typically water).

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Benefits and Features

  • In-line thermistor provides automatic temperature compensation
  • Compatible with most Campbell Scientific dataloggers
  • Agitator available that keeps the sensor clean and moves water across membrane for more accurate readings

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


Detailed Description

Oxygen diffuses through the CS511’s membrane onto a cathode that produces a chemical reaction. An electrical current is produced by this reaction, which is converted from microamps to millivolts by an in-line resistor. An in-line thermistor provides automatic temperature compensation.

Because the CS511 is shipped dry, DO electrolyte needs to be added before using the sensor. DO electrolyte as well as spare membranes are included in the sensor’s shipping kit.

Currently, the CS511 is Sensorex’s Model DO6400/T. Prior to June 2008, the CS511 was Sensorex’s Model DO6200/T. Programming, wiring, and most specifications are the same for these two sensors. However, they use different accessories and look different. Replacement parts remain available for the older DO6200/T. (See the Ordering Info on the web page.)

For an image of the older DO6200/T, see the retired version of the CS511 manual. Contact Campbell Scientific for more information.


Operating Temperature Range 0° to 50°C
Measurement Range 0.5 to 50 ppm (for O2)
Accuracy ±2%
Output 33 mV ± 9 mV (100% saturation); < 2 mV (0% saturation)
Response Time 5 min from 100% to 0% oxygen
Minimum Water Velocity 5 cm s-1 (2 in. s-1) across membrane
Minimum Submersion Depth 6.35 cm (2.5 in.)
Pressure 0 to 100 psig
Temperature Compensation Automatic from 4° to 40°C
Probe Electrolyte NaCl + glycerol (prevents freezing)
Diameter 5.72 cm (2.25 in.)
Height 17.78 cm (7 in.) from bottom of sensor to end of cable strain relief
Shipping Weight 0.8 kg (1.75 lb) including sensor and shipping kit


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


Product Compatible Note
CR1000 (retired)
CR200X (retired)
CR211X (retired)
CR216X (retired)
CR5000 (retired)
CR9000 (retired)

Additional Compatibility Information

DO Electrolyte

Because the CS511 is shipped dry, DO electrolyte needs to be added before using the sensor. DO electrolyte as well as spare membranes are included in the sensor’s shipping kit.


The PT4 agitator is offered for applications where the water velocity is less than 2.5 cm per second (1 in. s-1). It sweeps a brush across the sensor membrane to keep the sensor clean and provide water movement for accurate readings.

Frequently Asked Questions

Number of FAQs related to CS511-L: 10

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  1. A standard reference table for dissolved oxygen in water/temperature/elevation is included.

  2. Yes. This probe is completely submersible.

  3. No. The cable is attached to the internal electronics. Removing them would be a violation of the warranty.

  4. Generally, two to three times a year. However, if the membrane gets damaged, clean it accordingly.

  5. To incorporate a sensor that is compatible with wireless sensor interfaces into a wireless network, a CWS900-series wireless sensor interface is needed, as well as an A205 CWS-to-PC interface to configure it. 

  6. If the probe will be shelved for a month or more, the electrode should be removed. When the sensor will be used again, use fresh electrolyte and a new membrane. Following these guidelines will enable the probe to be stored indefinitely.

  7. The CS511-L is a galvanic dissolved-oxygen probe that is designed to work in water. As O2 passes through the semipermeable membrane, the oxygen reacts with the electrolyte solution in the probe. As more oxygen becomes available, an electro-chemical process occurs, so that an increase in the mV output is recorded. The source of the oxygen can be through the air, water, or a liquid slurry. Soil is not very homogeneous, so the dissolved oxygen is not able to move freely.

  8. 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. 

  9. Most Campbell Scientific sensors are available as an –L, which indicates a user-specified cable length. If a sensor is listed as an –LX model (where “X” is some other character), that sensor’s cable has a user-specified length, but it terminates with a specific connector for a unique system:

    • An –LC model has a user-specified cable length for connection to an ET107, CS110, or retired Metdata1.
    • An –LQ model has a user-specified cable length for connection to a RAWS-P weather station.

    If a sensor does not have an –L or other –LX designation after the main model number, the sensor has a set cable length. The cable length is listed at the end of the Description field in the product’s Ordering information. For example, the 034B-ET model has a description of “Met One Wind Set for ET Station, 67 inch Cable.” Products with a set cable length terminate, as a default, with pigtails.

    If a cable terminates with a special connector for a unique system, the end of the model number designates which system. For example, the 034B-ET model designates the sensor as a 034B for an ET107 system.

    • –ET models terminate with the connector for an ET107 weather station.
    • –ETM models terminate with the connector for an ET107 weather station, but they also include a special system mounting, which is often convenient when purchasing a replacement part.
    • –QD models terminate with the connector for a RAWS-F Quick Deployment Station.
    • –PW models terminate with the connector for a PWENC or pre-wired system.
  10. Many Campbell Scientific sensors are available with different cable termination options. These options include the following:

    • The –PT (–PT w/Tinned Wires) option is the default option and does not display on the product line as the other options do. The cable terminates in pigtails that connect directly to a datalogger.
    • In the –C (–C w/ET/CS110 Connector) option, the cable terminates in a connector that attaches to a CS110 Electric Field Meter or an ET-series weather station.
    • In the –CWS (–CWS w/CWS900 Connector) option, the cable terminates in a connector that attaches to a CWS900-series interface. Connection to a CWS900-series interface allows the sensor to be used in a wireless sensor network.
    • In the –PW (–PW w/Pre-Wire Connector) option, the cable terminates in a connector that attaches to a prewired enclosure.
    • In the –RQ (–RQ w/RAWS Connector) option, the cable terminates in a connector that attaches to a RAWS-P Permanent Remote Automated Weather Station.

    Note: The availability of cable termination options varies by sensor. For example, sensors may have none, two, or several options to choose from. If a desired option is not listed for a specific sensor, contact Campbell Scientific for assistance.

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