Campbell CS547A User manual

Revision: 02/2022
Copyright © 1994– 2022
Campbell Scientific, Inc.

Table of contents
1. Introduction 1
2. Precautions 1
3. Initial inspection 1
4. QuickStart 1
5. Overview 4
5.1 EC sensor 5
5.2 Conductivity interface 5
6. Specifications 6
6.1 CS574A probe 6
6.2 Temperature sensor 7
6.3 A547 interface 7
7. Installation 8
7.1 Site selection 8
7.2 Mounting 8
7.3 Wiring 8
7.4 Programming 9
7.4.1 EC measurement 10
7.4.2 Ionization correction 10
7.4.3 Temperature measurement 10
7.4.4 Correct EC measurement for temperature errors 11
7.4.5 Output processing 11
8. Operation 12
8.1 Calibration 12
8.1.1 Conversion factors 12
8.1.2 Typical ranges 12
8.1.3 Factory calibration 12
8.1.4 Field calibration 12
8.2 Deriving a temperature compensation coefficient 13
8.3 Analysis of ionization-error correction 13
Table of Contents - i

8.4 Schematics 14
9. Maintenance 15
Appendix A. Importing Short Cut code into CRBasic Editor 16
Table of Contents - ii

1. Introduction
The CS574A probe monitors the electrical conductivity (EC) and temperature of fresh water. It
connects to a Campbell Scientific data logger using the A547 interface. This probe is compatible
with most Campbell Scientific data loggers.
NOTE:
This manual provides information only for CRBasic data loggers. For retired Edlog data logger
support, see an older manual at www.campbellsci.com/old-manuals .
2. Precautions
lREAD AND UNDERSTAND the Safety section at the back of this manual.
lThe CS574A and A547 are precision instruments. Please handle them with care.
lCAUTION: Rapid heating and cooling of the CS574A, such as leaving it in the sun and then
submersing it in a cold stream, may cause irreparable damage.
lDo not use the CS574A with long cable lengths in an electrically noisy environment.
3. Initial inspection
lUpon receipt of the CS574A and A547, inspect the packaging and contents for damage.
File damage claims with the shipping company.
lImmediately check package contents against the shipping documentation. Contact
Campbell Scientific about any discrepancies.
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
CS574A Conductivity and Temperature Probe and A547 Interface 1

wiring terminals. Short Cut is available as a download on www.campbellsci.com . It is included
in installations of LoggerNet,RTDAQ, and PC400.
The following procedure also shows using Short Cut to program the CS574A.
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 CS574A or locate the sensor in the Sensors
>Water >Quality >CS547A Conductivity and Temperature Probe folder. Double click on
the CS547A Conductivity and Temperature Probe. Type the Cell Constant Kc (printed on
the sensor label), Lead Length in Feet, and Temperature Correction (Deriving a
temperature compensation coefficient (p. 13)). Temperature defaults to degree Celsius. This
can be changed by clicking the Deg C box and selecting Deg F, for degrees Fahrenheit, or K
for Kelvin.
CS574A Conductivity and Temperature Probe and A547 Interface 2

4. Click on the Wiring tab to see how the sensor is to be wired to the A547 and data logger.
5. In Output Setup, type the scan rate, meaningful table names, and Data Output Storage
Interval. Click Next.
CS574A Conductivity and Temperature Probe and A547 Interface 3

6. Select the measurement and its associated output option.
7. Click Finish and save the program. Send the program to the data logger if the data logger
is connected to the computer.
8. If the sensor is connected to the data logger, check the output of the sensor in the data
display in LoggerNet,RTDAQ, or PC400 to make sure it is making reasonable
measurements.
5. Overview
One A547 interface is required for each CS574A when used directly with the data logger; multiple
CS574A probes can connect to one AM16/32B multiplexer and one A547 interface.
Electrical conductivity (EC) of a solution is a simple physical property, but measurements can be
difficult to interpret. This manual instructs the user how to make EC measurements with the
CS574A. Accuracy specifications apply to measurements of EC in water containing KCl, Na2SO4,
NaHCO3, and/or NaCl, which are typical calibration compounds, and to EC not yet compensated
for temperature effects.
Statements made on methods of temperature compensation or estimating dissolved solids are
included to introduce common ways of refining and interpreting data, but are not definitive.
Authoritative sources to consult include the USGS Water-Supply Paper 1473, The pH and
Conductivity Handbook published by OMEGA Engineering, physical chemistry texts, and other
sources.
CS574A Conductivity and Temperature Probe and A547 Interface 4

Features:
lCompatible with AM16/32-series multiplexers allowing measurement of multiple sensors
lRounded ends facilitate installation and removal
lEasy to clean
lCorrosion resistant
lWeighted option available for stand-alone submersion
lCompatible with Campbell Scientific CRBasic data loggers: CR6, CR1000X, CR800-series,
CR3000, CR1000
5.1 EC sensor
The CS574A consists of three stainless steel rings mounted in an epoxy tube (FIGURE 5-1 (p. 5)).
Resistance of water in the tube is measured by excitation of the center electrode with positive
and negative voltage. This electrode configuration eliminates the ground looping problems
associated with sensors in electrical contact with earth ground. Temperature is measured with a
thermistor in a three-wire half-bridge configuration.
FIGURE 5-1. CS574A Conductivity and Temperature Probe
5.2 Conductivity interface
The A547 interface (FIGURE 5-2 (p. 6)) consists of blocking capacitors and bridge completion
resistors housed in a metal case. Screw terminals are provided for connecting the data logger,
and a water conductivity probe or multiplexer. Keep the interface in a non-condensing
environment that is maintained within the temperature range of the unit. Typically, the A547 is
housed in the data logger enclosure.
CS574A Conductivity and Temperature Probe and A547 Interface 5

FIGURE 5-2. A547 Interface
6. Specifications
6.1 CS574A probe
Housing: Epoxy
Length: 89 mm (3.5 in)
Width: 25.4 mm (1 in)
Height: 19 mm (0.75 in)
Minimum pipe ID in which
CS574A fits: 28 mm (1.1 in)
Maximum cable length: 305 m (1000 ft). The sensor must be ordered with desired
length as cable cannot be added to existing probes.
Depth rating: 305 m (1000 ft) maximum
pH range: Solution pH of less than 3.0 or greater than 9.0 may damage
the stainless steel housing.
Electrodes: Passivated 316 SS with DC isolation capacitors.
Cell constant: Individually calibrated. The cell constant (Kc) is found on a
label near the termination of the cable.
Operating temperature range: 0 to 50 °C
CS574A Conductivity and Temperature Probe and A547 Interface 6

EC range: ~ 0.005 to 7.0 mS/cm
EC measurement error
Bridge measurement error: <1%
Calibration error: In KCl and Na2SO4, NaHCO3, and NaCl standard solutions
at 25 °C:
±5% of reading (0.44 to 7.0 mS/cm)
±10% of reading (0.005 to 0.44 mS/cm)
Ionization error of KCl and Na+
solutions after correction: < 2.0%, 0.45 to 7.0 mS/cm
< 8.0%, 0.005 to 0.45 mS/cm
Weight with 4 ft cable: 120 g (4.2 oz)
6.2 Temperature sensor
Thermistor: Betatherm 100K6A1
Range: 0 to 50 °C
Accuracy1
Worst case: ±0.4 °C ( –24 to 48 °C)
±0.9 °C ( –35 to 50 °C)
Interchangeability error: ±0.10 °C (0 to 50 °C)
±0.20 °C at –10 °C
±0.30 °C at –20 °C
±0.40 °C at –30 °C
±0.50 °C at –40 °C
Steinhart-Hart equation error: ≤±0.01 °C ( –35 to 50 °C)
1Overall probe accuracy is a combination of thermistor interchangeability, bridge-resistor accuracy, and error of the
Steinhart-Hart equation. Bridge resistors have 0.1% tolerance with a 10 ppm temperature coefficient.
Interchangeability is the principle component error.
6.3 A547 interface
Length: 64 mm (2.5 in)
Height: 46 mm (1.8 in)
Width: 23 mm (0.9 in)
CS574A Conductivity and Temperature Probe and A547 Interface 7

Weight: 45 g (2 oz)
Temperature rating: –15 to 50 °C
7. Installation
If you are programming your data logger with Short Cut, skip Wiring (p. 8) and Programming (p.
9). Short Cut does this work for you. See QuickStart (p. 1) for a Short Cut tutorial.
7.1 Site selection
The CS574A measures the EC of water inside the hole running through the sensor, so detection
of rapid changes in EC requires the probe be flushed continuously. To do this in flowing streams,
simply orient the sensor parallel to the direction of flow. In stilling wells and ground wells,
however, diffusion rate of ions limits the response time.
7.2 Mounting
The housing and sensor cable are made of water impervious, durable materials. Mount the probe
so that it avoids contact with abrasives and moving objects. Because of slight positive buoyancy,
either secure the sensor to a fixed or retractable object or use the weighted cable option.
The split mesh strain relief sleeve on the cable can minimize strain. The split mesh sleeve is
recommended for cable lengths over 30m (100ft).
The A547 interface is usually mounted in the data logger enclosure.
7.3 Wiring
Wiring is shown in FIGURE 7-1 (p. 9).
WARNING:
Wire the conductivity excitation and temperature excitation lines in different excitation ports
or measurement errors will occur. If multiple CS574A/A547s are wired to one data logger,
each conductivity excitation must use a separate excitation port. However, you can wire
multiple temperature excitation lines into the same excitation port.
CS574A Conductivity and Temperature Probe and A547 Interface 8

FIGURE 7-1. CS574A wiring diagram
7.4 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,
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. 16).
The data logger program needs to measure the EC, measure the internal temperature sensor,
and correcting the EC measurement for resistance, ionization, and temperature errors.
Programming basics for CRBasic data loggers are in the following sections. Downloadable
example programs are available at www.campbellsci.com/downloads/cs547a-program-
examples . Programming basics and programming examples for Edlog data loggers are
provided at www.campbellsci.com\old-manuals .
CS574A Conductivity and Temperature Probe and A547 Interface 9

7.4.1 EC measurement
NOTE:
Older data loggers, such as the CR800-series and CR1000, use a different method to measure
EC. Refer to the CR1000 example program at www.campbellsci.com/downloads/cs547a-
program-examples for more information.
1. Measure the voltage output using the BrFull() CRBasic instruction. The BrFull()
instruction has the following format:
BrFull ( Dest, Reps, Range, DiffChan, ExChan, MeasPEx, ExmV, RevEx, RevDiff,
SettlingTime, fN1, Mult, Offset)
A typical BrFull() instruction follows:
BrFull(Rs,1,mV5000,1,VX1,1,2500,True,True,450,4000,-0.001,1)
2. Convert voltage measurement to resistance (Eq. 1 (p. 10)):
Rs = (Rs/(1 – Rs)) Eq. 1
Where Rs is the solution resistance.
3. Subtract the resistance error (Eq. 2 (p. 10)):
Rs = Rs – (C_length × 0.000032 + 0.005) Eq. 2
Where: C_length is the cable length in feet (printed on the sensor cable)
4. Calculate the EC (Eq. 3 (p. 10)):
Ct = (1/Rs) × KC Eq. 3
Where, Ct is EC without temperature correction, and KC is printed on the sensor label.
7.4.2 Ionization correction
The equation used to correct for ionization in the EC measurement depends on the EC value. For
EC values less than 0.475 use Eq. 4 (p. 10) and use Eq. 5 (p. 10) for values greater than or equal to
0.475:
Ct = Ct × 0.95031 – 0.00378 Eq. 4
Ct = –0.02889 + (0.98614 × Ct) + (0.02846 × Ct2)Eq. 5
7.4.3 Temperature measurement
The Therm107() measurement instruction programs CRBasic data loggers to measure the
CS574A internal temperature sensor. It applies a precise excitation voltage, makes a half-bridge
CS574A Conductivity and Temperature Probe and A547 Interface 10

resistance measurement, and converts the result to temperature using the Steinhart-Hart
equation. See Measurement and output linearization section in the 107 manual for more
information. Therm107() instruction and parameters are as follows:
Therm107(Dest, Reps, SEChan, VxChan, SettlingTime, Integ/fN1, Mult, Offset)
Set Mult to 1 and Offset to 0, which reports temperature as degree Celsius. If the sensor is in
an electronically noisy environment, set the Integ/fN1 to the 60 Hz or 50 Hz. Set the
SettlingTime to 20000 to compensate for long cable lengths (>91m (300ft)).
7.4.4 Correct EC measurement for temperature errors
Temperature of the sample solution can cause large errors in the EC measurement. Eq. 6 (p. 11)
corrects for temperature by assuming a linear relationship between temperature and EC. This
method generally produces values within 2% to 3% of a measurement made at 25°C.
Cond = (Ct × 100)/((Temp_C – 25) × TempCoef + 100) Eq. 6
Where Cond is EC in mS/cm corrected for temperature; Temp_C is the value returned by the
Therm107() instruction; and TempCoef is a temperature coefficient. The best corrections are
made when the temperature coefficient is determined at a temperature near field conditions. See
Deriving a temperature compensation coefficient (p. 13) for details on how to determine the
temperature coefficient. If determining the temperature coefficient is not possible, use a value of
2%/°C as a rough estimate.
7.4.5 Output processing
Over large ranges, EC is not linear and it is recommended to use the Sample CRBasic instruction.
In limited ranges, averaging measurements over time may be acceptable; this is accomplished by
using the Average instruction in CRBasic. Convention requires that the temperature at the time
of the measurement be reported.
CS574A Conductivity and Temperature Probe and A547 Interface 11

8. Operation
8.1 Calibration
8.1.1 Conversion factors
1 S (Siemens) = 1 mho = 1/ohm
Although mS·cm–1 and µS·cm–1 are the commonly used units of EC, the SI base unit is S·m–1. The
result of the example programs is mS·cm–1.
EC measurements can be used to estimate dissolved solids. For high accuracy, calibration to the
specific stream is required. However, for rough estimates, values between 550 and 750(mg/L)/
(mS/cm) are typical with the higher values generally being associated with waters high in sulfate
concentration (USGS Water-Supply Paper #1473, p. 99). A common practice is to multiply the EC
in mS·cm–1 by 500 to produce ppm or mg/L.
8.1.2 Typical ranges
Single distilled water will have an EC of at least 0.001mS·cm–1. ECs of melted snow usually range
from 0.002 to 0.042mS·cm–1. ECs of stream water usually range from 0.05 to 50.0 mS·cm–1, the
higher value being close to the EC of sea water (USGS Water-Supply Paper 1473, p. 102).
8.1.3 Factory calibration
The CS574A is shipped with a cell constant calibrated in a 0.01 molal KCl solution at 25.0°C
±0.05°C. The solution has an EC of 1.408 mS/cm.
8.1.4 Field calibration
The cell constant is a dimensional number expressed in units of cm–1. The unit cm–1 is slightly
easier to understand when expressed as cm·cm–2. Because it is dimensional, the cell constant as
determined at any one standard, will change only if the physical dimensions inside the CS574A
probe change. Error due to thermal expansion and contraction is negligible. Corrosion and
abrasion, however, have the potential of causing significant errors.
A field calibration of the CS574A cell constant can be accomplished as follows:
1. Make a 0.01molal KCL solution by dissolving 0.7456g of reagent grade KCl in 1000g of
distilled water, or purchase a calibration solution.
CS574A Conductivity and Temperature Probe and A547 Interface 12

2. Clean the probe thoroughly with the black nylon brush shipped with the CS574A and a
small amount of soapy water. Rinse thoroughly with distilled water, dry thoroughly, and
place in the KCl solution.
3. Connect the CS574A and A547 or probe and interface to the data logger using the wiring
described in Wiring (p. 8). Program the data logger to make the field calibration. A
downloadable calibration program is available at
www.campbellsci.com/downloads/cs547a-program-examples .
The calibration solution temperature must be between 1 and 35°C; a polynomial is used to
correct for temperature errors within this range. The solution constant of 1.408mS/cm (for
prepared solution mentioned previously), is valid only for a 0.01molal KCl solution.
8.2 Deriving a temperature compensation
coefficient
1. Place the CS574A in a sample of the solution to be measured. Bring the sample and the
probe to 25°C.
2. Download the measurement program from www.campbellsci.com/downloads/cs547a-
program-examples in the data logger and record the Ct at 25°C. This number will be
C25 in the formula in Step 4.
3. Bring the solution and the probe to a temperature (t) near the temperature at which field
measurements will be made. This temperature will be t (in °C) in the formula. Record Ct at
the new temperature. This number will be C in the formula in Step 4.
4. Calculate the temperature coefficient (TC) using the following formula.
Enter TC in the appropriate variable as shown in the program segment in the example program
available at www.campbellsci.com/downloads/cs547a-program-examples .
8.3 Analysis of ionization-error correction
FIGURE 8-1 (p. 14) and FIGURE 8-2 (p. 14) show the amount of correction applied by the example
programs to compensate for ionization effects on the measurements. Also shown is an ideal
correction. Factors were derived by measuring the standard solutions with values of 0.0234, 0.07,
0.4471, 07, 1.413, 2.070, 3.920, and 7.0mScm–1.
CS574A Conductivity and Temperature Probe and A547 Interface 13

FIGURE 8-1. Plot of ideal and actual correction between 0 and 0.44 mS cm–1
FIGURE 8-2. Plot of ideal and actual correction between 0.44 and 7.0 mS cm–1
8.4 Schematics
The CS574A schematic is provided in FIGURE 8-3 (p. 15), and the A547 schematic is provided in
FIGURE 8-4 (p. 15).
CS574A Conductivity and Temperature Probe and A547 Interface 14

FIGURE 8-3. CS574A conductivity and temperature circuit diagram
FIGURE 8-4. A547 Interface circuit diagram
9. Maintenance
Routine maintenance includes thoroughly cleaning the orifice of the CS574A probe with the
black nylon brush provided and some soapy water. Rinse thoroughly.
CS574A Conductivity and Temperature Probe and A547 Interface 15

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 .
CS574A Conductivity and Temperature Probe and A547 Interface 16

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.