The SR50A is a rugged acoustic sensor for measuring the distance from the sensor to a target. It is typically used to measure snow or water depth, but it is well-suited for other uses.
Because the speed of sound in air varies with temperature, an independent temperature measurement is required to compensate the distance reading. A simple calculation is applied to initial readings for this purpose.
Note: This sensor may not be suitable for marine environments.Read More
The "-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 depths and 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.
|Measurement Time||< 1.0 s|
|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 datalogger’s 12 Vdc power supply)|
|Measurement Range||0.5 to 10 m (1.6 to 32.8 ft)|
|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|
|Length||10.1 cm (4.0 in.)|
|Diameter||7.5 cm (3 in.)|
|Weight||375 g (13.2 oz) without cable|
|Cable Weight||250 g (8.2 oz) for a 4.57-m (15-ft) cable|
Maximum Cable Length
|SDI-12||60 m (200 ft)|
|RS-232||60 m (200 ft) Baud rates ≤ 9600 bps|
300 m (984 ft)
Cable lengths greater than 60 m require a heavier gage wire if the power supply drops below 11 Vdc.
|Typical Active||250 mA|
|Quiescent SDI-12 Mode||< 1.0 mA|
|Quiescent RS-232/RS-485 Modes||
To achieve an unobstructed view for the SR50A's beam, the SR50A is typically mounted to a tripod mast, tower leg, or user-supplied pole via the CM206 6-ft crossarm. The 19517 mounting kit attaches directly to the crossarm. The 19484 mounting stem attaches to the crossarm via the 17953 NU-RAIL fitting or CM220 right-angle mount. If the surface is at an angle, the CM230 Adjustable Inclination Mount should be used instead of the NU-RAIL fitting or CM220 mount.
Number of FAQs related to SR50A-L: 17
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No. The maximum cable length is approximately 800 ft.
Yes, but more routine maintenance of the sensor is needed in marine environments.
Yes. The accuracy of the sensor is 1 cm or 0.4% of distance to water (whichever is greater). As long as the water level is deeper than this, the water height can be confidently determined.
Yes. This sensor has an SDI-12 output.
Approximately 800 feet. This is a function of the limitations of the SDI-12 signal.
The potential error is roughly ±0.4% of distance for a ±25° Celsius variation away from 0° Celsius.
Because the speed of sound changes with temperature, Campbell Scientific recommends using the SR50A-L in tandem with a temperature sensor for the most accurate measurements.
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.