The SR50A Sonic Distance Sensor provides a non-contact method for determining snow depth. It determines depth by emitting an ultrasonic pulse and then measuring the elapsed time between the emission and return of the pulse. An air temperature measurement is required to correct for variations of the speed of sound in air.
Note:Campbell Scientific recommends modelSR50A-EE-Lfor operation in extreme environmental conditions where corrosion is a concern (such as coastal regions).
Read MoreThe "-L" on a product model indicates that the cable length is specified at the time of order.
The SR50A was designed to meet the stringent requirements of measuring snow depth, and it uses a multiple echo processing algorithm to help ensure measurement reliability.
SDI-12, RS-232, and RS-485 output options are available for measuring the SR50A. Campbell Scientific’s MD485 interface can be used to connect one or more SR50A sensors in RS-485 mode to an RS-232 device. This can be useful for sensors that require lead lengths that exceed the limits of either RS-232 or SDI-12 communications.
The SR50A replaced the SR50 in March 2007. The newer SR50A is smaller and has different output options than its predecessor. TheSR50AHis available with a heater option for locations where rime ice is a problem.
Measurement Description | Snow depth |
Measurement Time | < 1.0 s |
Measurement Range | 0.5 to 10 m (1.6 to 32.8 ft) |
Output Options | SDI-12 version 1.3, RS-232, RS-485 (output options selected by configuring internal jumpers) |
Baud Rates | 1200 to 38400 bps (RS-232, RS-485 modes) |
Power Requirements | 9 to 18 Vdc (typically powered by data logger’s 12 Vdc power supply) |
Beam Acceptance | ~30° |
Resolution | 0.25 mm (0.01 in.) |
Accuracy | ±1 cm (0.4 in.) or 0.4% of distance to target (whichever is greatest). Requires external temperature compensation. |
Operating Temperature Range | -45° to +50°C |
Temperature Accuracy |
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Compliance | CE Compliant |
Length | 10.1 cm (4.0 in.) |
Diameter | 7.5 cm (3 in.) |
Cable Weight | 250 g (8.2 oz) for a 4.57-m (15-ft) cable |
Weight |
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Maximum Cable Length |
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-NOTE- | Cable lengths greater than 60 m require a heavier gage wire if the power supply drops below 11 Vdc. |
SDI-12 | 60 m (200 ft) |
RS-232 | 60 m (200 ft) Baud rates ≤ 9600 bps |
RS-485 | 300 m (984 ft) |
Power Consumption |
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Active | 250 mA (typical) |
Quiescent SDI-12 Mode | < 1.0 mA |
Quiescent RS-232/RS-485 Modes |
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Note:The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.
Product | Compatible | Note |
---|---|---|
21X(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR10(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR1000(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR1000X | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR10X(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR200X(retired) | SDI-12 | |
CR206X(retired) | SDI-12 | |
CR211X(retired) | SDI-12 | |
CR216X(retired) | SDI-12 | |
CR23X(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR295X(retired) | SDI-12 | |
CR300 | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR3000(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR310 | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR350 | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR500(retired) | SDI-12 | |
CR5000(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR510(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR6 | SDI-12, RS-232, and RS-485 | |
CR800 | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR850 | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. | |
CR9000(retired) | ||
CR9000X(retired) | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. |
Product | Compatible | Note |
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GRANITE 6 | SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface. |
CR6 and CR1000X programs that directly read each type of SR50A output (SDI-12, RS-232, RS-485), and a CR1000 program that reads the RS-485 output using an MD485 Multidrop interface. A 107 sensor provides the temperature measurement needed for temperature compensation. The programs use the data filtering method described in the manual.
Number of FAQs related toSR50A-L:15
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No. The maximum cable length is approximately 800 ft.
Approximately 800 feet. This is a function of the limitations of the SDI-12 signal.
This sensor requires regular maintenance in a marine environment. The SR50A-L functions properly if care is taken to keep the vent free of salt accumulation and the interior free of moisture by replacing the desiccant as needed. It may also be necessary to carefully clean the face of the sensor to remove salt deposits.
Yes. This sensor has an SDI-12 output.
No. This causes echoes and reflections that confuse the sensor.
The potential error is roughly ±0.4% of distance for a ±25° Celsius variation away from 0° Celsius.
The sensitivity can be adjusted slightly at the factory, but it cannot be recalibrated. Typically, the transducing diaphragm needs to be replaced periodically to maintain calibration. This can be done by the user or at the factory.
Position the sensor at a height that is between 0.5 m and 10 m above the target.
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