Onset S-LIA Specifications

Photosynthetically Active Radiation (PAR)

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Smart Sensor (S-LIA-M003) Manual

The photosynthetically active radiation (PAR) smart sensor is designed to work with HOBO®
stations. The smart sensor has a plug-in modular connector that allows it to be added easily to a
station. All calibration parameters are stored inside the smart sensor, which automatically
communicates configuration information to the logger without any programming, calibration, or
extensive user setup.

Specifications

PAR Smart Sensor

S-LIA-M003

Accessories:

• Light sensor mounting
bracket (M-LBB)

• Light sensor level (M-LLA)

Measurement Range

Accuracy

Angular Accuracy Cosine corrected 0 to 80 degrees from vertical; Azimuth Error <2%

Resolution

Drift < ±2% per year

alibration Factory recalibration available

Operating Temperature Range -40° to 75°C (-40° to 167°F)

Environmental Rating Weatherproof

Housing Anodized aluminum housing with acrylic diffuser and O-ring seal

Dimensions 4.1 cm height x 3.2 cm diameter (1 5/8 x 1 1/4 in)

Weight 120 g (4 oz)

Bits per Sample 10

Number of Data Channels* 1

Measurement Averaging Option Yes

able Length Available

Length of Smart Sensor
Network Cable*

* A single HOBO station can accommodate 15 data channels and up to 100 m (328 ft) of smart sensor cable (the digital

communications portion of the sensor cables).

0 to 2500 μmol/m

±5 μmol/m
temperature induced error ±0.75 μmol/m
(0.42 μmol/m

error at 45 degrees from vertical, 360 degree rotation

2.5 μmol/m

3.0 m (9.8 ft)

3.0 m (9.8 ft)

The CE Marking identifies this product as complying with all relevant
directives in the European Union (EU).

2

/sec, wavelengths 400 to 700 nm (see Plot A)

2

/sec or ± 5%, whichever is greater in sunlight; Additional

2

/sec/°F from 77°F)

2

/sec

2

/sec/°C from 25°C

Typical Quantum Response

The PAR smart sensor is designed to detect photons between 400-700 nm in wavelength. Ideally
the sensor would count photons with equal efficiency between 400-700 nm and no photons
would be counted outside this range. However, in reality, this sensor undercounts photons
between 400-550 nm and between 670-700 nm, and it over counts photons between 550-670 nm.
In most applications (where the sensor is used in natural sunlight) the error is not significant.

Plot A: PAR Smart Sensor Typical Quantum Response

5942-F MAN-S-LIA

PAR Smart Sensor (S-LIA-M003) Manual

Mounting

Bracket Mounting

It is recommended that you mount the PAR smart sensor with
the light sensor mounting bracket (M-LBB) on a pole or tripod.
To mount the PAR smart sensor using the bracket:

5

1. Attach the light sensor bracket to a 1¼ inch - 1
with the provided U-bolts.

Note: The light sensor bracket can also be mounted on a
flat, vertical surface using four screws.

2. Position the light sensor on top of the light sensor bracket
with its cable running through the slot in the bracket.

3. Using the two screws supplied, attach the sensor to the
bracket through the two holes on either side of the slot.

Note: Do not completely tighten the screws until you level
the light sensor.

4. Position the bracket so it faces toward the equator,
minimizing the chance of shading.

5. Mount the light sensor bracket on the mast with the two U-
bolt assemblies, mounting it high enough on the mast to
avoid the possibility of shading the light sensor.

Note: If you mount the light sensor above eye level, it is
recommended that you use a step ladder or other secure
platform when leveling the sensor so that you can clearly
view the light sensor level (M-LLA).

Mast

PAR sensor

/8 inch pole

10. Check the light sensor level and repeat above steps if
necessary.

11. When the light sensor is level, remove the light sensor level
from the light sensor.

PAR sensor level

PAR sensor

Leveling the PAR Smart Sensor on

the Light Sensor Bracket

Specialized Application Mounting

To mount the light sensor using a mounting plate of your own
design:

1. Drill a 0.56 (9/16) inch hole in the middle of the plate, then
drill two #25 holes 1.063 (1-1/16) inches apart on either
side of the center hole. Cut a 0.31 (5/16) inch-wide slot in
the mounting plate as shown below. The plate should be a
thickness of 1/8 inch or less.

2. Slide the sensor through the 0.31 (5/16) inch-wide slot.

3. Attach the sensor using two 6-32 x 3/8 inch screws and lock
washers (not included).

4. Shim the sensor as necessary to level it

Light sensor

Thumbscrew

PAR sensor cable

bracket

U-bolt assembly

PAR Smart Sensor Bracket Mounting

6. Make sure the screws holding the sensor to the mounting
bracket are loose.

7. Place the light sensor level on the light sensor.

8. Adjust the height of the thumbscrews to level the sensor
(start with the thumbscrews protruding about 1/16

inch

from the bracket).

9. Once the sensor is near level, tighten the Phillips head
screws.

Recommended Mounting Plate Dimensions

Mounting Considerations

• Small errors in alignment can produce significant errors.
Be certain that the sensor is mounted level.

• Mount the light sensor where it will not be in a shadow.

• If possible, avoid locating the sensors in dusty locations.

Dust, pollen, and salt residue that collect on the top of the
sensor can significantly degrade accuracy.

• Refer to the station manual and Tripod Setup Guide for
more information regarding setting up stations.

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