Campbell CS250DM User manual

12/2020
Copyright © 2020
Campbell Scientific, Inc.

Table of contents
1. Introduction 1
2. Precautions 1
3. Initial inspection 1
4. QuickStart 1
5. Overview 4
6. Specifications 5
7. Installation 7
7.1 Siting 7
7.2 Installation in a radiation shield 9
7.3 Mount the shield 10
7.4 Wiring 10
7.5 Programming 10
7.5.1 RS-485 programming 11
7.6 Long cable lengths 12
7.7 Modbus register map 12
7.8 Device Configuration Utility 13
8. Maintenance and troubleshooting 15
8.1 Maintenance 16
8.2 Troubleshooting 16
Appendix A. Importing Short Cut code into CRBasic Editor 17
Table of Contents - i

1. Introduction
The CS250DM delivers extremely accurate and precise air temperature data necessary for IEC
61724 Class A solar monitoring applications and delta temperature (ΔT) calculations for
temperature gradient and stability analysis.
2. Precautions
lREAD AND UNDERSTAND the Safety section at the back of this manual.
lWhen opening the shipping package, do not damage or cut the cable jacket. If damage to
the cable is suspected, consult with a Campbell Scientific support engineer.
lAlthough rugged, the CS250DM should be handled as a precision scientific instrument.
3. Initial inspection
lUpon receipt of the CS250DM, inspect the packaging and contents for damage. File
damage claims with the shipping company.
lThe model number, cable length, Modbus address, and serial settings are printed on a
label at the connection end of the cable. Check this information against the shipping
documents to ensure the expected product and cable length were received.
4. QuickStart
A video that describes data logger programming using Short Cut is available at:
www.campbellsci.com/videos/cr1000x-data logger-getting-started-program-part-3 .Short Cut
is an easy way to program your data logger to measure the sensor and assign data logger wiring
terminals. Short Cut is available as a download on www.campbellsci.com. It is included in
installations of LoggerNet,RTDAQ,PC400, and PC200W.
The following procedure also shows using Short Cut to program the CS250DM.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 1

1. Open Short Cut and click Create New Program.
2. Double-click the data logger model.
3. In the Available Sensors and Devices box, type CS250DM. You can also locate the sensor in
the Sensors >Temperature folder. Double click the sensor model. Type the RS-485 address;
default address is printed on the cable. The RS-485 address must be unique and may need
to be changed if another sensor on the terminal has the same address. Refer to Device
Configuration Utility (p. 13) for information on changing the address. The temperature
defaults to degree C. This can be changed by clicking the Temperature box and selecting
one of the other options.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 2

4. Click on the Wiring tab to see how the sensor is to be wired to the data logger. Click OK
after wiring the sensor.
5. Repeat steps three and four for other sensors you want to measure. Click Next.
6. In Output Setup, type the scan rate, a meaningful table name, and the Data Output
Storage Interval.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 3

7. Select the measurement and its associated output option.
8. Click Finish and save the program. Send the program just created to the data logger if the
data logger is connected to the computer.
9. If the sensor is connected to the data logger, check the output of the sensor in the data
display in LoggerNet,RTDAQ,PC400, or PC200W to make sure it is making reasonable
measurements.
5. Overview
The CS250DM uses a precision PT-1000 class A platinum resistor thermometer (PRT) to provide
the highest level of accuracy. The cable includes a Campbell Scientific precision analog-to-
digital, smart-sensor module for making the measurements. The module design is optimized for
the class A PRT that minimizes self-heating and lead-wire resistance. Measurement electronics
are surge protected with 1200 V isolation and environmentally protected with a rugged
overmolding with an IP65 rating.
When exposed to sunlight, the CS250DM should be housed in the 41303-5A 6-plate radiation
shield or RAD06 6-plate radiation shield.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 4

Features:
lHigh accuracy and precision
lExceeds IEC 61724-1 standards for ambient air temperature measurements
lExceeds EPA standards for ΔT measurements when used with an aspirated radiation shield
lDigital Modbus RS-485 output ensuring data quality over long cable lengths
lCompatible CRBasic data loggers: CR6, CR1000X, CR3000 (with MD485), CR800 series (with
MD485), CR300 series (with MD485), CR1000 (with MD485),
lEasily interfaces with the MeteoPV Platform without coding
lDirectly connects with Modbus RTU RS-485 Networks
6. Specifications
Sensing element:
Precision: 1000 ohm Class A platinum (PT1000)
Accuracy: ± (0.15 + 0.002t) °C
Long-term stability: Maximum Rodrift = 0.04%
after 1000 hours at 400 °C
Measurement temperature range: –75 to +250 °C
Time constant: 15 seconds in 5 m/s wind
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 5

Measurement uncertainty: ± (0.15 + 0.002t) °C
Element stem material: 316L Stainless Steel sheathed
Surge protection: 1200 V isolation
Supply voltage: 5 to 30 VDC
Temperature coefficient: TCR = 3850 ppm/K
Communications 24-bit ADC
Protocol: Modbus RTU protocol (over RS-485)
Format: 8 data bits, 1 stop bit, even parity as default (user-
configurable)
Baud rate: 19,200 bps as default (user-configurable)
Modbus ID: Last two digits of serial number as default (user-
configurable)
Stem diameter: 0.32 cm (0.125 in)
Overall stem length: 6.35 cm (2.5 in)
Cable (Sensor head to DM board)
Wire size and type: 24 AWG (7/32,RT38) copper
Insulation type: PFA insulated (Teflon®)
Insulation rating: –75 to +250 °C
Sheath: Thin PFA sheathed overall
Number of cores: 3
Physical properties: Good abrasion and moisture resistance
Overall diameter: 2.1 mm (0.08 in)
Sensor dimensions: 17.2 x 11.1 x 6.1 cm (6.8 x 4.4 x 2.4 in)
Cable (DM board to PT)
Wire size and type: 24 AWG (7/32) tinned copper
Insulation type: PVC
UL: AWM 10012 1000V 105°C
Filler: Fibrillated polypropylene as required for uniform
round construction
Drain: 24 AWG (7/32) tinned copper
(cabled, touching foil)
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 6

Shield: Aluminum/Mylar (100% coverage, 25% minimum
overlap, foil facing in)
Nominal wire diameter: 0.61 mm (0.024 in)
Weight: 90.7 g with 3.2 m cable
(0.2 lb with 10.5 ft cable)
Compliance: View documents at:
www.campbellsci.com/cs250dm
7. Installation
If you are programming your data logger with Short Cut, skip Wiring (p. 10), and Programming
(p. 10). Short Cut does this work for you. See QuickStart (p. 1), for a Short Cut tutorial.
This section discusses the following.
7.1 Siting 7
7.2 Installation in a radiation shield 9
7.3 Mount the shield 10
7.4 Wiring 10
7.5 Programming 10
7.6 Long cable lengths 12
7.7 Modbus register map 12
7.8 Device Configuration Utility 13
7.1 Siting
The general EPA guidance for standard meteorological stations is to locate the sensor over an
open, level area at least 9 m (29.5 ft) in diameter. The surface should be covered by short grass or
the natural earth surface where grass does not grow. Sensors should be located at a distance of
at least ten times the height of any nearby obstruction and at least 30 m (98.4 ft) from large,
paved areas. Sensors should be protected from thermal radiation and adequately ventilated.
Protect the filter at the top of the sensor from exposure to liquid water.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 7

FIGURE 7-1. Clearances
The sensor should be installed at a standard measurement height which varies depending on the
guides being used:
l1.5 m (4.92 ft) (AASC)
l1.25 to 2.0 m (4.1 to 6.5 ft) (WMO)
l2.0 m (6.5 ft) (EPA)
When used in the field, the CS250DM must be housed in a radiation shield. Typically, the RAD06
6-plate radiation shield is used.
The white color of these shields reflects solar radiation, and the louvered construction allows air
to pass freely through, thereby keeping the sensor at or near ambient temperature. The RAD06
uses a double-louvered design that offers improved sensor protection from insect intrusion and
driving rain and snow. In addition, compared to shields of a similar appearance, the RAD shields
have lower self-heating in bright sunlight combined with low wind speeds giving a better
measurement. The RAD06 attaches to a crossarm, mast, or pipe with a 2.5 to 5.3 cm (1.0 to 2.1
inch) outer diameter.
Tools required for installing a radiation shield to a tripod or tower include:
ladjustable wrench (to suit 12 mm (1/2 in) nuts)
lsmall screwdriver provided with data logger
lsmall Phillips screwdriver
lUV-resistant cable ties
lsmall pair of diagonal-cutting pliers
ladjustable wrench with a minimum 50 mm (2 in) jaw size.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 8