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

7.2 Installation in a radiation shield
1. Insert the CS250DM in the sleeve.
2. Loosen the nut on the entry gland at the bottom of the shield.
3. Insert the sensor into the gland.
4. First tighten the nut on the gland by hand until the sensor is held firmly in place. Then use
the large adjustable wrench to further tighten the gland by 1/2 to 1 turn.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 9

7.3 Mount the shield
1. Attach the radiation shield to the tripod mast, crossarm, or tower leg using the supplied
U-bolt or band clamp.
2. Route the cable to the data logger, and secure the cable to the mounting structure using
cable ties.
CAUTION:
Failure to secure the cable can lead to breakage of the wires due to fatigue caused by
blowing back and forth in the wind.
7.4 Wiring
The RS-485 output can be directly read by a MeteoPV, CR6, CR1000X, or Modbus RTU RS-485
network (Table 7-1 (p. 10)). Other Campbell Scientific data loggers can use an MD485 multidrop
interface to read the RS-485 output. Refer to the MD485 manual for more information. The
Modbus address must be unique and may need to be changed if another sensor on the bus has
the same address. Change the Modbus address using the Device Configuration Utility or through
Modbus commands. For more information, refer to Device Configuration Utility (p. 13) or
Modbus register map (p. 12).
Table 7-1: Wire Color, Station Connection, and Function
Wire color Station or data logger
terminal Function
Blue A– (Codd) RS-485 A/A' [–]
White/blue striped B+ (Ceven) RS-485 B/B' [+]
Brown 12V 5 to 30 VDC
White/brown striped GGround (power)
Green GModbus common
Clear GShield
7.5 Programming
Short Cut is the best source for up-to-date programming code for Campbell Scientific data
loggers. If your data acquisition requirements are simple, you can probably create and maintain a
data logger program exclusively with Short Cut. If your data acquisition needs are more complex,
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 10

the files that Short Cut creates are a great source for programming code to start a new program
or add to an existing custom program.
NOTE:
Short Cut cannot edit programs after they are imported and edited in CRBasic Editor.
AShort Cut tutorial is available in QuickStart (p. 1). If you wish to import Short Cut code into
CRBasic Editor to create or add to a customized program, follow the procedure in Importing
Short Cut code into CRBasic Editor (p. 17). Programming basics for CRBasic data loggers are
provided in the following section. A downloadable example program is available at
www.campbellsci.com/downloads/cs250dm-program-example.
7.5.1 RS-485 programming
The RS-485 output can be directly read by a CR6-series, CR1000X-series, or Modbus RTU RS-485
network. Other Campbell Scientific data loggers can use an MD485 multidrop interface to read
the RS-485 output. Refer to the MD485 manual for information about using the MD485.
A CR6 or CR1000X data logger programmed as a Modbus Master can retrieve the values stored in
the Input Registers (Modbus register map (p. 12)). To do this, the CRBasic program requires
SerialOpen() followed by ModbusMaster(). The SerialOpen instruction has the
following syntax:
SerialOpen (ComPort, Baud, Format, TXDelay, BufferSize, Mode)
The Format parameter is typically set to logic 1 low; even parity, one stop bit, 8 data bits. The
Mode parameter should configure the ComPort as RS-485 half-duplex, transparent.
The ModbusMaster() instruction has the following syntax:
ModbusMaster (Result, ComPort, Baud, Addr, Function, Variable, Start, Length,
Tries, TimeOut, [ModbusOption])
The Addr parameter must match the sensor Modbus address. The Modbus address must be
unique and may need to be changed if another sensor on the terminal has the same address. The
default value for the Modbus address is the last two digits of the sensor serial number, with
exceptions for serial numbers ending in 00 and 01. These exceptions default to Modbus addresses
of 110 and 111, respectively. The default Modbus address and serial settings are printed on the
cable. To collect all of the CS250DM values, the Start parameter needs to be 1 and the
Length parameter needs to be 5. ModbusOption is an optional parameter described in the
CRBasic Editor Help.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 11

7.6 Long cable lengths
Digital data transfer eliminates offset errors due to cable lengths. However, digital
communications can break down when cables are too long, resulting in either no response from
the sensor or corrupted readings. Maximum cable lengths depend on the number of sensors
connected, the type of cable used, and the environment of the application. Follow these
guidelines when using long cables:
lUse low capacitance, low resistance, screened cable (as supplied by Campbell Scientific) to
reach distances of several hundred meters.
lEnsure that the power ground wire has low resistance and is connected to the same ground
reference as the data logger control terminals.
lBe aware that daisy-chaining sensors reduces the maximum cable length roughly in
proportion to the number of sensors connected in parallel.
7.7 Modbus register map
Table 7-2 (p. 12) provides the input register map (function code 4) and Table 7-3 (p. 13) provides
the holding register map (functions 3, 6, and 16).
Table 7-2: Input register map
Input register Value Modbus
data type Description
30001 Serial number Float1Specifies the sensor serial number
assigned by the factory
30003 Temperature Float1The stored value is in degrees Celsius.
30005 Counter Float1
The counter provides an indicator
that the sensor is actively taking
measurements. This value will
increment once per measurement,
resetting to 0 after 10,000.
30007 Sensor status Float10 = good
1 = open/short
30009 Temperature
range check Float10 = good/in range 1 = out of range
1Modbus float is a 32-bit integer.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 12

Table 7-3: Holding register map
Holding register Value Modbus
data type Description
40001 Modbus address Unsigned short1Modbus device address (1 to 247)
40002 Baud rate Unsigned short1
1 = 9600 bps
2 = 19200 bps
3 = 38400 bps
4 =57600 bps
5 = 115200 bps
40003 Parity Unsigned short1
0 = no parity
1 = odd
2 = even
40004 Stop bit Unsigned short11 = 1 stop bit
2 = 2 stop bits
40005 Termination
resistor Unsigned short10 = off/disable 1 = on/enable
1Unsigned short data is a 16-bit positive integer.
7.8 Device Configuration Utility
Device Configuration Utility is bundled in Campbell Scientific data logger support software and is
available, at no cost, from www.campbellsci.com/downloads. Use Device Configuration Utility to
change the CS250DM settings, view stored values, and update the CS250DM operating system
(OS). It also provides CS250DM wiring information.
Connection to Device Configuration Utility requires a USB-to-RS-485 adapter and a 12VDC
power supply. Use the following procedure for connecting to Device Configuration Utility:
1. Open Device Configuration Utility.
2. Under Device Type, click CS250DM.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 13

3. Follow steps listed under Connecting to a CM250DM with a USB to RS-485 adapter.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 14

Click the Holding Registers tab to change settings. The default Modbus address and serial
settings are printed on the cable. The Modbus address must be unique and may need to be
changed if another sensor on the terminal has the same address. The default value for the
Modbus address is the last two digits of the sensor serial number, with exceptions for serial
numbers ending in 00 and 01. These exceptions default to Modbus addresses of 110 and 111,
respectively. Most Modbus systems use the default Baud Rate,Parity,Stop Bits, and
Termination Resistor values.
Click the Input Registers tab to view the stored values.
8. Maintenance and
troubleshooting
NOTE:
All factory repairs and recalibrations require a returned material authorization (RMA) and
completion of the “Statement of Product Cleanliness and Decontamination” form. Refer to
the Assistance page at the end of this manual for more information.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 15

8.1 Maintenance
The CS250DM requires minimal maintenance. Periodically check cabling for proper connections,
signs of damage, and possible moisture intrusion. Check the radiation shield monthly to make
sure it is free from dust and debris. To clean the shield, first remove the sensor. Dismount the
shield. Brush all loose dirt off. If more effort is needed, use warm, soapy water and a soft cloth or
brush to thoroughly clean the shield. Allow the shield to dry before remounting.
8.2 Troubleshooting
Symptom: Temperature is NAN, –INF, –9999, –273
Verify wiring of sensor to the data logger; cross-reference data logger program or the
measurement system wiring diagram.
Symptom: Incorrect Temperature
Check the cable for signs of damage and possible moisture intrusion.
Symptom: Unstable Temperature
Make sure the shield and ground wires are connected to data logger ground, and the data
logger is properly grounded.
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 16

Appendix A. Importing Short
Cut code into CRBasic Editor
Short Cut creates a .DEF file that contains wiring information and a program file that can be
imported into the CRBasic Editor. By default, these files reside in the C:\campbellsci\SCWin
folder.
Import Short Cut program file and wiring information into CRBasic Editor:
1. Create the Short Cut program. After saving the Short Cut program, click the Advanced tab
then the CRBasic Editor button. A program file with a generic name will open in CRBasic.
Provide a meaningful name and save the CRBasic program. This program can now be
edited for additional refinement.
NOTE:
Once the file is edited with CRBasic Editor,Short Cut can no longer be used to edit the
program it created.
2. To add the Short Cut wiring information into the new CRBasic program, open the .DEF file
located in the C:\campbellsci\SCWin folder, and copy the wiring information, which is at
the beginning of the .DEF file.
3. Go into the CRBasic program and paste the wiring information into it.
4. In the CRBasic program, highlight the wiring information, right-click, and select Comment
Block. This adds an apostrophe (') to the beginning of each of the highlighted lines, which
instructs the data logger compiler to ignore those lines when compiling. The Comment
Block feature is demonstrated at about 5:10 in the CRBasic | Features video .
CS250DM PT-1000 Class A, Precision Air Temperature Sensor 17

Limited warranty
Products manufactured by Campbell Scientific are warranted by Campbell Scientific to be free
from defects in materials and workmanship under normal use and service for twelve months from
the date of shipment unless otherwise specified on the corresponding product webpage. See
Product Details on the Ordering Information pages at www.campbellsci.com. Other
manufacturer's products, that are resold by Campbell Scientific, are warranted only to the limits
extended by the original manufacturer.
Refer to www.campbellsci.com/terms#warranty for more information.
CAMPBELL SCIENTIFIC EXPRESSLY DISCLAIMS AND EXCLUDES ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Campbell Scientific hereby
disclaims, to the fullest extent allowed by applicable law, any and all warranties and conditions
with respect to the Products, whether express, implied or statutory, other than those expressly
provided herein.