Campbell CS241DM User manual

08/2021
Copyright © 2021
Campbell Scientific, Inc.

Table of contents
1. Introduction 1
2. Precautions 1
3. Initial inspection 1
4. QuickStart 2
5. Overview 4
6. Specifications 6
7. Installation 8
7.1 Wiring 8
7.2 Data logger programming 9
7.2.1 Programming 9
7.3 Placement on a photovoltaic (PV) module 10
7.4 Mounting/cable strain relief 10
7.4.1 Adhesive mounting strip 11
7.4.2 Cable strain relief 11
7.4.3 Extreme sealing tape 12
8. Operation 14
8.1 Electrical noisy environments 14
8.2 Long cable lengths 14
8.3 Modbus register map 14
8.4 Device Configuration Utility 16
9. Maintenance and troubleshooting 17
9.1 Maintenance 17
9.2 Troubleshooting 18
Appendix A. Importing Short Cut code into CRBasic Editor 19
Appendix B. Sensor material properties 20
B.1 3M F9473PC adhesive 20
Table of Contents - i

1. Introduction
The CS241DM temperature sensor uses a precision 1000 ohm Class A platinum resistance
thermometer (PRT) to measure temperature. It is designed for measuring the back-of-
photovoltaic (PV) module temperature but also can be used to measure the surface temperature
of other devices. The CS241DM has a digital RS-485 output that can be directly read by a
MeteoPV, CR6, CR1000X, or Modbus RTU RS-485 network. Other Campbell Scientific data
loggers can use an MD485 multidrop interface to read the RS-485 output.
NOTE:
This manual provides information only for CRBasic data loggers.
2. Precautions
lREAD AND UNDERSTAND the Safety section at the back of this manual.
lDo not use epoxy to secure the sensor head to a PV module.
lBefore mounting, the installers need to wash their hands and then clean the back of the PV
module or other device .
lPrying the sensor head off will likely damage both the sensor and PV module.
lProper strain relief of the cable is required after mounting the sensor to the measurement
surface (Mounting/cable strain relief (p. 10)).
lPlacement of the cable inside a rugged conduit is advisable for cable runs over 4.5 m (15 ft),
especially in locations subject to digging, mowing, traffic, power tools, animals, or lightning
strikes.
3. Initial inspection
lUpon receipt of the sensor, inspect the packaging and contents for damage. File damage
claims with the shipping company.
lThe model number and cable length 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.
CS241DM PT-1000 Class A, Back-of-Module Temperature Sensor1

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, or PC400.
The following procedure also shows using Short Cut to program the CS241DM.
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 CS241DM. You can also locate the sensor in
the Sensors > Temperature folder. Double click CS204DM/CS241DM. Type the RS-485
address; default address is the last two digits of the serial number. The CS241DM must have
a unique RS-485 address. The surface temperature defaults to degree C. This can be
changed by clicking the Temperature box and selecting one of the other options.
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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.
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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
logger support software data display in LoggerNet, RTDAQ, or PC400 to make sure it is
making reasonable measurements.
5. Overview
The CS241DM is a surface mountable platinum resistive thermometer (PRT) that measures back-
of-module temperature for solar energy applications. It uses a precision PT-1000 Class A PRT to
provide the highest level of accuracy. To withstand the harsh treatment that commonly occurs
with meteorological station installation, the sensing element is safely housed inside a specially
designed self-adhesive aluminum disk (FIGURE 5-1 (p. 5)).
The disk protects the PRT, particularly during installation, and promotes heat transfer from the
surface. An adhesive tab on the disk fastens the sensor to the measurement surface.
The CS241DM 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 wire resistance. Measurement electronics are surge protected with
1200 V isolation and environmentally protected with a rugged overmolding.
CS241DM PT-1000 Class A, Back-of-Module Temperature Sensor4

The CS241DM provides PV stakeholders with highly accurate back-of-module temperature, even
at long cable lengths, in power performance modeling and simulation of solar energy
applications. Back-of-module temperature is critical for any evaluation of effective irradiance and
power conversion.
FIGURE 5-1. CS241DM temperature sensor
Benefits and features:
lDesigned for optimal performance on bifacial PV module
lEasy installation
lNIST-traceable, serialized calibration certificate supplied with every sensor
lMeets or exceeds IEC 61724 Class A performance specifications
lPrecision PT-1000 Class A sensing element
lCompliant with IEC 60751, DIN EN 60751 (according to IEC 751)
lSlim design to minimize sensor impact on bifaciality (<2% of full-size cell area)
lThermal conductance greater than 600 W/(m2 K)
lMaximum sensor-to-module bonding
lHigh temperature rating to 150 °C
lInternal four-wire measurement with 24-bit A/D and precision resistor maximize
measurement accuracy
lCompatible with Campbell Scientific 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 programming
lConnects directly to a Modbus RTU RS-485 network
CS241DM PT-1000 Class A, Back-of-Module Temperature Sensor5

6. Specifications
Sensor: Precision 1000 ohm Class A platinum sensing element
Class A sensor accuracy: ± (0.15 + 0.002t) °C
Operating temperature range: –40 to 150 °C
Temperature coefficient: TCR = 3850 ppm/K
Long-term stability: Maximum R0 drift = 0.04% after 1000 hours at 400 °C
Temperature uncertainty: ±(0.3 to 0.4 °C) for the –40 to 100 °C measurement range
when using the CR1000X data logger
Disk diameter: 2.54 cm (1.0 in)
Height: 0.419 cm (0.165 in)
Disk material: Anodized aluminum
Shipping weight: 90.7 g (0.2 lb)
Analog-to-digitalmodule (DM): 24-bit ADC
A/D measurement
uncertainty: ±0.015 °C
Supply voltage: 5 to 30 VDC
Power consumption: 15 mA
Surge protection: 1200 V isolation
Environmental protection: Rugged overmolding
IP rating: IP68 rating (self certified); 1 m submersion for 90 min
Communications:
Protocol: Modbus RTU (over RS-485)
Format: 8 data bits, 1 stop bit, even parity as default (user
configurable)
Baud rate: 19200 bps as default (user-configurable)
Modbus ID: Last two digits of serial number as default (user-
configurable)
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Approvals: Conforms with the Restriction of Hazardous Substances
Directive (RoHS2)
Compliance: View compliance documents at:
www.campbellsci.com/cs241dm
 Meets or exceeds IEC 61724 Class A performance
specifications
Industrial standards: Compliant with IEC 60751, DIN EN 60751,
Industrial Design (IEC Class 4) (according to IEC 751)
IP rating: IP68 rating (self certified): 1 m (3 ft) submersion for 90
minutes
EMC compliance: Conforms with Electromagnetic Compatibility Directive
(EMC)
RoHS2: Conforms with Restriction of Hazardous Substances
Directive (RoHS2)
POE compliance: POE compliant (802.3af) to 100 meters when installed per
recommendations in TIA TSB-184
CAT5e: Cable will meet CAT5e channel requirements to 100 meter
length
Sensor cable (sensor head-to-DM board)
Cable diameter: 0.216 cm (0.085 in)
Cable length: 0.9 m (3 ft)
Jacket material: White semi-gloss perfluoroalkoxy (PFA), insulated
Jacket rating: –75 to 250 °C
Minimum bend radius: 6 mm (0.25 in) at least 6 mm (0.25 in) away
from sensor disk
Connector: Circular plastic M12 , female 5-pin connector
Standard DM cable (DM board to pigtail)
Temperature rating: –40 to 105 °C
Overall cable diameter: 7.37 mm nominal ± 0.13 mm (0.29 inch nominal ± 0.005 in)
Conductor material: 22 AWG 19/0.0058 stranded tinned copper
Cable type: 4 twisted pairs twisted together and wrapped with clear
polyester tape to form a cable core
CS241DM PT-1000 Class A, Back-of-Module Temperature Sensor7

Connector: Circular, plastic, M12 male, 5-pin, A-coded connector
Jacket material: Thermoplastic elastomer, 1.07 mm (0.042 in) nominal wall
thickness (pressure)
Insulation material: High-density polyethylene 0.254 mm (0.01 in) nominal wall
thickness
Dielectric strength: 2000 V RMS
Approvals: UL AWM 2463 (80C 600V)
NEC (UL) TYPE PLTC
NEC (UL) TYPE CMX OUTDOOR – CM
CEC C(UL) TYPE CMX OUTDOOR – CM
PENNSYLVANIA D.E.P. – MSHA
7. Installation
If you are programming your data logger with Short Cut, skip and Data logger programming (p.
9). Short Cut does this work for you. See QuickStart (p. 2) for a Short Cut tutorial. This section
discusses the following:
7.1 Wiring 8
7.2 Data logger programming 9
7.3 Placement on a photovoltaic (PV) module 10
7.4 Mounting/cable strain relief 10
7.1 Wiring
The DM module is embedded in a short cable that attaches to the sensor head and has a 5-pin,
M12 female circular connector. A standard cable or a 3-twisted-pair shielded cable with a 5-pin
M12 male circular connector is used to attach the sensor to the station or data logger (Table 7-1
(p. 9)). Using connectors between the sensor head and the station or data logger cable allows in-
field sensor head replacement without disconnecting the cable from the data logger.
The following table provides sensor wiring and cable pin-out. Detailed information about the
cables are provided in the Specifications (p. 6). Sensor wiring is also available in the Device
Configuration Utility and the MeteoPV User Interface.
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Table 7-1: Wire Color, Station Connection, and Function
Standard cable1
wire color Pin-out
3-twisted pair
cable1
wire color
Station (data
logger)
terminal
Function
Blue 3 Green A– (C odd) RS-485 A/A [–]
White/blue stripe 2 White B+ (C even) RS-485 B/B [+]
Brown 4 Red 12V 5 to 30 VDC
White/brown stripe 1 Black GGround (power)
Green 5 Yellow GModbus common
-- N/A Clear GShield
1Cable has an 8-pin M12 connector.
7.2 Data logger programming
Short Cut is the best source for up-to-date data logger programming code. 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, 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.
A Short Cut tutorial is available in QuickStart (p. 2). 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. 19). Programming basics for CRBasic data loggers are
provided in the following section. Downloadable program example is available at
www.campbellsci.com/downloads/cs241dm-program-example .
If applicable, please read Electrical noisy environments (p. 14) and Long cable lengths (p. 14) prior
to programming your data logger.
7.2.1 Programming
NOTE:
Programming basics for the CR6 and CR1000X data loggers are provided in this section.
Contact Campbell Scientific if using a data logger that requires an MD485 interface.
CS241DM PT-1000 Class A, Back-of-Module Temperature Sensor9

A CR6 or CR1000X data logger programmed as a Modbus Master can retrieve the values stored
in the CS241DM Input Registers (Modbus register map (p. 14)). To do this, the CRBasic program
requires a SerialOpen() instruction followed by the ModbusMaster() instruction.
The SerialOpen instruction has the following syntax:

SerialOpen (ComPort, Baud, Format, TXDelay, BufferSize, Mode )

The Format 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 CS241DM Modbus address. Each Modbus address must be
unique on a Modbus network. 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. To collect all of the
CS241DM 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.
7.3 Placement on a photovoltaic (PV)
module
The PV module may or may not have distinctive photocells. If the PV module does not have
distinctive photocells, center the sensor on the back of the PV module. If the module has several
distinctive photocells, center the sensor on the back of the photocell that is the middle of the PV
module.
7.4 Mounting/cable strain relief
CAUTION:
Before mounting, the installers need to wash their hands and then clean the back of the PV
module or other device .
CS241DM PT-1000 Class A, Back-of-Module Temperature Sensor10

7.4.1 Adhesive mounting strip
A pressure-activated adhesive mounting strip is adhered to the flat surface of the aluminum disk.
To mount the sensor, remove the paper from the mounting strip and place the disk on the back
of the PV module or other device. Press the disk firmly for 2 to 3 seconds to initiate long-term
bonding of the sensor to the surface. The mounting strip must be adhered to a clean surface for
its adhesive to function properly.
CAUTION:
Do not use epoxy to secure the sensor head to a PV module.
7.4.2 Cable strain relief
NOTE:
Placement of the cable inside a rugged conduit is advisable for cable runs over 4.5 m (15 ft),
especially in locations subject to digging, mowing, traffic, power tools, animals, or lightning
strikes.
The cable must be properly strain relieved after mounting the sensor to the measurement
surface. To accomplish this, the CS241DM comes with three cable ties and three edge clips.
1. Fasten the edge clips at the top of the PV module in the following locations:
a. Above the sensor
CS241DM PT-1000 Class A, Back-of-Module Temperature Sensor11

b. On both sides of the DM board
NOTE:
A user-supplied coupler allows two CS241DM sensors to connect to the same
cable. Each CS241DM must have a unique Modbus address.
c. At a top corner of the PV module
2. Use the cable ties to secure the cable to the edge clips.
7.4.3 Extreme sealing tape
The CS241DM was designed to minimize surface area and mass. This design minimizes the
effects of installation on bifacial modules and also increases the adhesion properties of the
CS241DM PT-1000 Class A, Back-of-Module Temperature Sensor12

sensor to the module surface. When back-of-module temperatures may exceed 150°C, use
extreme sealing tape for additional adhesion and cabling relief.
To ensure the sensor disk and cable are adequately fastened to the measurement surface, use
three strips of tape in two places each:
1. For strain relief, place the first strip of tape across the cable 20 to 40cm (8 to 16in) from the
sensor head and rub the tape surface to remove bubbles.
2. Place the other strips of tape perpendicular and on top of the first strip of tape and rub the
tape surface to remove bubbles. These strips of tape should form an H (FIGURE 7-1 (p. 13)).
3. To secure the sensor to the module surface, remove the paper from the bottom of the disk
and adhere the disk to the PV module (Placement on a photovoltaic (PV) module (p. 10)).
4. Place a strip of tape across the sensor head, perpendicular to the cable and rub the tape
surface to remove bubbles. Rub as close as possible to the sensor disk.
5. Place the two other strips of tape on the ends of the sensor disk, perpendicular to the first
piece of tape and parallel to the cable then rub the tape surface into the module surface.
See the following figure.
FIGURE 7-1. Proper tape usage
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8. Operation
This section discusses the following:
8.1 Electrical noisy environments 14
8.2 Long cable lengths 14
8.3 Modbus register map 14
8.4 Device Configuration Utility 16
8.1 Electrical noisy environments
AC power lines, pumps, power inverters, and motors can be the source of electrical noise.
8.2 Long cable lengths
Placement of the cable inside a rugged conduit is advisable for cable runs over 4.5 m (15 ft),
especially in locations subject to digging, mowing, traffic, power tools, animals, or lightning
strikes.
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 fitted by Campbell Scientific) to
reach distances of several hundred meters.
lEnsure that the power ground cable 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.
8.3 Modbus register map
Table 8-1 (p. 15) provides the input register map (function code 4) and Table 8-2 (p. 15) provides
the holding register map (functions 3, 6, and 16).
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Table 8-1: 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.
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.
Table 8-2: 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.
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8.4 Device Configuration Utility
Device Configuration Utility is bundled in Campbell Scientific data logger support software and
can also be acquired, at no cost, from www.campbellsci.com/downloads . Device Configuration
Utility can be used to change the CS241DM settings, view stored values, and update the
CS241DM operating system (OS). It also provides wiring information.
To use Device Configuration Utility, the CS241DM must be connected to a computer and 12 VDC
power source. A USB-to-RS-485 adapter is required to connect the CS241DM to the computer.
The following is the procedure for connecting to Device Configuration Utility:
1. Open the Device Configuration Utility.
2. Under Device Type, click CS240DM Series.
3. Follow steps listed under Connecting to a CM240DM Series sensor with a USB to RS-485
adapter.
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4. Click the Holding Registers tab to change the settings. Except for the Modbus Address, the
default settings are typical for most Modbus systems and therefore, the settings rarely
need to be changed.
5. Click the Input Registers tab to view the values.
9. Maintenance and
troubleshooting
NOTE:
For all factory repairs, customers must get an RMA number. Customers must also properly fill
out a “Declaration of Hazardous Material and Decontamination” form and comply with the
requirements specified in it. Refer to the Assistance page at the back of this manual for more
information.
9.1 Maintenance
The CS241DM sensor requires minimal maintenance. Periodically check cabling for proper
connections, signs of damage, and possible moisture intrusion.
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9.2 Troubleshooting
Symptom: Incorrect Temperature
Check the cable for signs of damage and possible moisture intrusion.
Symptom: Unstable Temperature
Make sure the clear shield wire is connected to data logger ground, and the data logger is
properly grounded.
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