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: Campbell Scientific recommends model SR50A-316SS-L for marine environments.Read More
The SR50A was designed to meet the stringent requirements of measuring snow depth and water 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. The SR50AH is available with a heater option for locations where rime ice is a problem.
|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)|
|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.)|
|Cable Weight||250 g (8.2 oz) for a 4.57-m (15-ft) cable|
Maximum Cable Length
|-NOTE-||Cable lengths greater than 60 m require a heavier gage wire if the power supply drops below 11 Vdc.|
|SDI-12||60 m (196.9 ft)|
30 m (98.4 ft)
Baud rates ≤ 9600 bps
|RS-485||300 m (984.3 ft)|
|Active||250 mA (typical)|
|Quiescent SDI-12 Mode||< 1.0 mA|
|Quiescent RS-232/RS-485 Modes||
Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.
|CR1000||SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface.|
|CR300||SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface.|
|CR3000||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.|
|CR5000 (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.|
|CR9000X||SDI-12 and RS-232. For RS-485, requires an MD485 interface or similar RS-485 to RS-232 interface.|
One single-ended channel per probe is required; an excitation channel can be shared by several probes.
Number of FAQs related to SR50A-L: 17
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Yes, but more routine maintenance of the sensor is needed in marine environments.
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.
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.
No. The maximum cable length is approximately 800 ft.
Yes. This sensor has an SDI-12 output.
The potential error is roughly ±0.4% of distance for a ±25° Celsius variation away from 0° Celsius.
No. This causes echoes and reflections that confuse the sensor.
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.