Clamp dendrometer PDS40A / PDS40P / PDS40S
Clamp dendrometer PDS40A / PDS40P / PDS40S
Advantages at a glance
- small stem diameters
- stepless reading at high resolution
- simple and quick non-invasive attachment
- various interfaces for data output
Clamp dendrometer PDS40A / PDS40P / PDS40S
Clamp dendrometers are designed for the precise measurement of diameter changes in stems and branches. Their compact design enables easy and fast, non-invasive attachment to the measurement object. With a measurement range of 5 to 40 mm, they are suitable for measuring small stems and branches. The sensor is attached to the measurement object using three pressure levers, with the central measuring arm moving the rotary position sensor proportionally to the diameter of the measurement object. The contact pressure is designed to ensure stable positioning while minimizing the impact on plant tissue. The position sensor bearing is designed to minimize the effects of temperature and axial forces. The sensors are suitable for precise long-term measurements in the field and feature IP67 protection and an operating temperature range of −40 to 60 °C. The sensor requires minimal maintenance and energy.
Applications
- Monitoring growth patterns through continuous measurement of stem diameter changes
- Investigating water stress and tree responses to drought
- Assessing frost events and their effects on stems
- Investigating the relationship between soil water availability and plant response, particularly in combination with soil water potential measurements
- Long-term monitoring of plant development under natural field conditions
Variants
The three variants differ in the type of signal output:
- PDS40A: Analog voltage output directly proportional to the stem diameter.
- PDS40P: Ratiometric output signal proportional to the stem diameter and the supply voltage. Optionally available with a Mini Data Logger with IR data access.
- PDS40S – SDI: Digital output via the SDI-12 interface; the measured value is provided directly in millimeters of stem diameter. The sensor is individually calibrated at 100 measurement points over the entire measurement range to ensure excellent linearity.
Installation Instructions
The sensor should be mounted on a trunk (or branch) that is as straight and uniform in shape as possible, ensuring that the cable entry does not come into contact with the object being measured. The cable must be securely fastened to the trunk so as not to affect the sensor’s position.
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Parameters |
Specifications |
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Clamp dendrometer |
PDS40A |
PDS40P |
PDS40S - SDI |
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Weight of the sensor |
160 g |
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Measurement range |
5 … 40 mm |
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Resolution |
stepless reading
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1.24 µm |
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Accuracy |
±2% of the total range |
better than 0.3 mm |
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Output signal |
Analog: Voltage range 1000 … 1700 mV |
Ratiometric: Rotary Position Sensor 4,7 kΩ ±20 % |
Digital: SDI-12 Version 1.3 compatible
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Contact force |
1.5 … 2 N lateral levers, 2 … 3 N central measuring arm |
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Temperature dependence |
better than ±3 µm/K |
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Temperature measurement accuracy |
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±0.2 °C |
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Power Supply |
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Battery |
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Lithium-ion battery in the data logger |
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Supply Voltage |
5 … 16 V |
max. 16 V |
5 … 12 V |
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Power consumption |
0.75 mA |
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Power consumption in idle mode |
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30 µA |
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Power consumption during the measurement |
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6 mA |
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Warm-up time |
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300 ms |
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Connection |
4-pin M8 connector
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3-pin M8 connector |
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Environmental conditions
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Protection class |
IP67 |
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Operating temperature |
-40 … 60 °C |
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Humidity |
0 … 100 % |
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PTi Mini Data Logger for PDS40P
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Parameters |
Specifications |
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Channels
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1 |
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Input |
Resistor divider |
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Resistance range |
3.5 to 6 kOhm; 5 kOhm is recommended |
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Measurement intervals
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1 minute to 4 hours |
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Resolution |
16 bits |
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Memory size |
128 kByte |
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Storage capacity |
approx. 50,000 values |
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Data access |
via an IrDA/USB connection cable |
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Accuracy of the internal temperature |
±0,3 °C |
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Clock accuracy (-10 to 40 °C) |
better than ±15 seconds per month |
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Battery capacity |
~4 years with a 1-hour measurement interval |
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Size |
Ø22 x ~100 mm length, excluding cable |
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Weight |
40 g, including battery |
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Protection class |
IP68 |