Turtle Tough TT-HFC User manual

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turtletoughsensors.com
MANUAL
DSS HANDHELD FIELD COMMUNICATOR
Conducvity
CON

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TOUGH
®
Product name DSS HandHeld Field Communicator - Conducvity
Code TT-HFC
Mechanical
Housing ABS
 Handheld
IP Class Housing IP40
Connector Quick connect plug
Temperature Usage -15 to +50 °C (Storage -35 to +75 °C)
Weight 130 grams with baery (4.6 ounces) 100 grams without baery (3.5 ounces)
Dimensions D 26 x W 60 x H 120 mm (1.0” X 2.4” X 4.7”)
Electrical
Supply 9V baery (Alkaline or Lithium)
 ~45 mA with DSS sensor “On”
 ~6 hrs Alkaline or ~12 hrs Lithium
Auto shutdown aer 25 seconds * without communicaon
 Smart Digital DSS Modbus RTU Conducvity (EC) Sensors
Baud rate 9600 or 19,200 kbps (selectable)
CE mark EN61326A
* Number of seconds unl auto shutdown starts from when sensor is disconnected from HFC
DSS Handheld Field Communicator
for Conducvity DSS Sensors
The Handheld Field Communicator calibrates and
congures DSS Smart Digital RS485 Modbus RTU
sensors at any locaon. All values stored in non-
volale sensor EEPROM for hot-swap portability
when installed back into eld service.
Specicaons
CON

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Programming and Navigation
The Handheld Field communicator (HFC) has 3-digit display and 16 LEDs to show readings and analyc data
as well as to calibrate and congure sensor. Programming done by 4 key front panel. ‘Mode’ key used to toggle
and navigate to each LED. ‘Up’ or ‘Down’ buons scroll available opons and adjust values. ‘Mode’ key is used to
make selecons and save entries. ‘View’ key provides addional informaon for the given LED mode (see table for
details on use of ‘View’). Once baud rate and node of connected sensor are entered all parameters are automacally
loaded for zero conguraon plug and play use in the eld.
3-digit display
Use ‘Up’ or ‘Down’ buons
to scroll available opons
and adjust values.
Press ‘View’ for addional
informaon for the given
LED mode
Use ‘Mode’ key to make
selecons & save entries.

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Intelligent DSS Handheld Field Communicator for Calibraon, Conguraon,
Spot Measurement and Troubleshoong of Smart Digital RS485 Modbus RTU
Conducvity DSS Sensors
LED LABEL Parameter Descripon and Method to Access Range Default
Sensor Type Measurement type
Load opons for connected sensor
‘View’ key shows soware revision
‘Up’ key shows cell constant
‘Mode’ key used to exit and save
any changes and move onto
‘Reading’
pH or ORP or DO or ISE or CON
‘Down’ shows range mode: Standard (Std) /
High (Hi) or else Ultralow (UL)
‘Up’ key then used to iniate toggling
between Std & Hi Range Modes
Per Type
Reading***** Process Parameter ****
Display current calibrated value
0.01-9.99 μS/cm (value is ashing)
10.0-99.9 μS/cm (value is ashing)
100-999 μS/cm (value is ashing)
1.00-9.99 mS/cm (1,000–9,990 μS/cm)
10.0-99.9 mS/cm (10,000–99,900 μS/cm)
100-999 mS/cm (100,000–999,000 μS/
cm)
1.00-4.00 S/cm (Reading LED ashing)
Per
Measured
Soluon
Absolute mS Process Parameter Display the absolute conducvity
value from connector EC sensor
Same as Reading LED mode (see above)
Max raw conducvity is 4,000 mS/cm
Per Sensor
& Media
Cal Temp. Oset calibraon of
temperature in °C **
Adjust temp reading up & down
‘View’ key shows temperature oset ±25.0 °C * from raw value 0.0
 Oset Calibraon
Zero Dry in Air **
Denes the oset for dry in air
‘View’ shows current zero oset 0.00 to 2.00 % of the output Per Sensor
Cal Slope Denes Gain **
Denes gain on nominal cell
constant for all measured ranges
‘View’ shows current gain
0.300 to 1.700 mes nominal cell constant
yields eecve apparent calibrated cell
constant in eld use
Per Sensor
Dampener Smoothing dampener
& output delay ***
Sets number of seconds to be used
for dampener for process value(s) 1, 2, 3, 4, 5, 8, 10, 15, 20 or 30 Seconds
10 -
Dampen
1 - Delay
Step Change ‘Up’ & ‘Down’ buon
Sensivity seng
% increment for each me the
‘Up’ or ‘Down’ buon is depressed
Choices: 0.05, 0.10, 0.20, 0.5, 1.0 or 2.0
‘View’ selects TDS for Std/Hi Mode: ‘nA’
(NaCl), ‘PoT’ (KCl) or 442
0.05
Special
Set ATC Coecient
Display Computed EC
Unit 1 (Reg 30005)
Display Computed EC
Unit 2 (Reg 30006)
Set temp compensaon coecient
‘View’ shows PSU for for Std/Hi
MegaOhms (MΩ) for Sensor Type 7
HOLD ‘View’ shows TDS for Std/Hi
UPW MegaOhms (MΩ) for Ultralow
Units are % per °C (Limits are 0.00-9.99)
Salinity range is 0.000 to 50.000 PSU
Resisvity range is 0.000 to 20.000 MΩ
TDS shown in ppt. Convert ppt to ppm
mulply by 1,000 (2.34 ppt is 2,340 ppm)
Per Sensor
Default is
2.00%
Baudrate Baudrate for Com Toggle between 9600 or 19,200 kbps 9600 or 19,200 kbps Per System
Node Address for Com Choose a valid address on network From 001 to 247 Per Sensor
Item/Serial
Number
Sensor Item Number
and Serial Number
Item # denes model; ‘View’ shows
Serial # (unique traceable idener)
Item # from 0-65,535 (>999 is toggled)
Serial # per YY.M-AA.DDD Scheme Per Sensor
Days in Use Total me DSS sensor
is energized
Increments me in use to track
sensor lifeme and predicve
maintenance
0-65,535 in units of days (>999 is toggled)
Within ±2% accuracy for any me in use
Per Sensor
Field Use
Max/Min °C Displays max & Min
Temp in eld use
The max temp in eld use is shown;
Push ‘View’ buon for min temp -40 to +210 °C * Per Sensor Field Use
* Negave values are always shown as ashing.

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Color notes
Parameters in light green are dened by factory at dispatch me or determined from eld use.
Parameters in grey can be adjusted as desired.
Parameters in dark green are obtained from wet calibraons done with DSS sensor in the eld.
Scaling Display Notes
When reading is less than 1.00 mS/cm the value will ash indicang that the units are in μS/cm instead of mS/cm.
When reading is greater than 999 mS/cm, ‘Reading LED’ will ash and units will switch to S/cm ( i.e. 1.34 Siemens/
cm is equivalent to 1,340 mS/cm ).
** Holding the ‘View’ key for 3 to 5 seconds in this LED mode shows the ‘Days in Use’ SINCE this calibraon was performed
** Holding BOTH the ‘View’ AND ‘Up’ keys for 3 to 5 seconds in this LED mode will reset all calibraon values back to default
*** Holding the ‘View’ key for 3 to 5 seconds allows for the delay from boot value to be shown as well as adjusted
**** Holding both ‘Up’ & ‘Mode’ keys shows soware rev or both ‘Down’ & ‘Mode’ keys shows build date in Reading LED mode
***** User Adjustable Timeout Feature: Press ‘Down’ + ‘View’ in ‘Reading’ mode to set minutes before automac shuto occurs

• The “Modbus Com” LED is illuminated briey each me that a communicaon packet is sent or received.
• The “Baery Low” LED will at rst ash as warning and then illuminate connuously when the 9V baery
should be replaced.
oMUST Change 9V baery when LED is illuminated to ensure valid readings and calibraons
Smart Digital DSS Conductivity Sensor Features and Basic Usage
The smart digital DSS conducvity sensors with integral Modbus RTU communicaons allows for simple and fully
portable installaon scheme. Sensor may be calibrated anywhere (lab, shop or eld) and interfaced with any data
acquision or control system in the eld via the RS-485 Modbus RTU communicaons. The temperature oset
and process value oset calibraons can be done with sensor le in service to agree with a reference value for an
external measurement device (please see calibraon instrucons). Waterproof and corrosion-resistant NEMA 6P
quick connect plugs comes standard for easy seamless hot-swap of sensors from service for cleaning, recalibraon
and other maintenance tasks as may be required as well as eventual replacement of sensor in me.

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Setup of DSS RS-485 Modbus RTU Sensor to Handheld Field Communicator
1. Press the ‘Mode’ buon to turn on HFC. The HFC will aempt to communicate with the last used baudrate
and node address. If either no sensor is connected or available at the last used baudrate and node address
then three dashes “---” are shown on display. If no buons is pressed for 25 seconds the HFC will automacally
turn itself o to conserve baery life.
a) If previous baudrate & node are valid HFC will automacally load all relevant LED opons and address-
able parameters for that sensor type.
2. Pressing ‘Mode’ buon navigates to ‘Node’ LED mode. Use ‘Up’ & ‘Down’ keys to scroll to node of the con-
nected sensor. Node informaon is typically found on label of sensor. If this informaon is not available, the
DSS Windows soware can be used scan the sensor in queson to determine the current node address.
The baudrate and node address of the DSS sensors can only be changed by the Windows soware. When
the desired node address is reached press the ‘Mode’ key enter the value.
a) Default nodes: pH is 1, ORP is 2, Wide-Range ORP is 3, DO is 4, ISE is 5, Conducvity is 6. If mulple
sensors of same type are used on one Modbus RTU network then node address for each same type sensor
must dier from default to ensure a unique and valid node address.
3. If baudrate needs to be adjusted (9600 or 19,200 kbps) then the HFC automacally navigates to this LED
mode next.
4. HFC returns to reading mode aer selecng node & baudrate. If selecons are valid then process reading is
shown else three dashes “---” are shown.
5. Press ‘Mode’ buon aer reading LED to toggle to sensor type LED which shows type of sensor that is
connected.

• Inial node of ‘0’ will be shown (press ‘Mode’ when node address is ‘0’ to exit scan mode).
Select starng address for scan with ‘Up’ or ‘Down’ keys. Node address scrolled in increments of 10.
For example, pressing ‘Up’ key gives address of 1à10à20à30… and so forth while pressing ‘Down’ key
gives addresses of à240à230à220… and so forth.
• Press ‘Mode’ to begin scan. Scanning is always performed in an ascending fashion. Scan will stop when sensor
is found. Sensor type for node address found displayed ashing with node address.
• Press ‘Mode’ to select this node and you will enter ‘Reading’ mode.
• Press ‘View’ to connue scanning. If no sensors found when address 247 is reached, then ‘Err’ is displayed.
Press ‘Mode’ to resume scan and repeat these procedures.
** Select the current node for the aached sensor.
If the current node is not known use the node scanning feature to determine it. When in the ‘Baud Rate’ LED
mode, hold the ‘View’ key for at least 3 seconds to iniate the node changing mode. The current node of the
sensor will be shown and the ‘Sensor Type’ and ‘Node’ LED will ash.
If the ‘Mode’ key is pressed immediately aer entering this node changing mode, then no change to the address
will be made since the address displayed will equal the current node address. Use ‘Up’ and ‘Down’ keys to adjust
the nodeto the modied address if desired. Press ‘Mode’ key to enter the new node address selected with ‘Up’ &
‘Down keys.
Notes on adjustable smoothing dampener and output delay
• Dampener LED when DSS-CON sensor is connected allows for display and modicaon of the variable that
is used to set the number of seconds used for the smoothing dampener and delay from boot to send the
output values.
• For intermient operaon, it is recommended to set this dampener and output delay variable to a low number
in order to minimize power consumpon while from baery power sources and maximize sampling me of
process output.

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Sensor Serial Number, Item Number and Total Time in Field Service
Systemac tracking achieved with factory stamped sensor serial and item number. The internal clock on the
DSS sensor board is incremented when energized to monitor the total number of days in acve eld service.
If the sensor is disconnected the incremenng of the me in service will stop. When the sensor is energized
the incremenng of me in service will once again resume. The number of days in service is always the actual
real-me total usage. The total days in use is shown in days and equally accurate for connuous or intermient
service such that the me in service is accurate even if the sensor is taken in and out of use for cleaning and
re-calibraon and/or swapped between dierent installaons.
Important note before performing calibraons
The me averaging dampener is always on even when performing calibraons. It can be desirable to adjust
dampener to a short value when performing calibraons to make the calibraon process quicker and then reset
the dampener back to a higher value before reinstalling the sensor back into connuous use in eld service
(be sure to remember this last step!)
Temperature Calibraon Instrucons
The temperature is calibrated by pushing the ‘Up’ or ‘Down’ buons when in the temperature display (°C) mode. *
Calibraon of DSS Conducvity Sensors with Handheld Field Communicator
1. Use the ‘Mode’ buon to toggle to ‘Oset’ LED to perform the zero dry in air calibraon. The sensor should
be completely dry and clean before starng this calibraon. Pressing ‘Up’ or ‘Down key will iniate an auto-
calibraon.
2. Use the ‘Mode’ buon to toggle to the ‘Slope’ LED and use ‘Up’ and ‘Down’ keys unl the display reads the de-
sired value in conducvity units. If the number is not ashing and the LED is not ashing the units will be mS/cm.
a. If the number displayed is ashing the units are then μS/cm (divide by 1,000 to get mS/cm units)
b. If the ‘Slope’ LED is ashing, then the units are Siemens/cm (mulply by 1,000 to get mS/cm units)
 

3. Calibraon values stored inside DSS smart digital conducvity sensor in EEPROM so sensor can be powered
down without loss of calibraon meaning a true plug and play seamless hot-swap measurement system in
the eld.
4. Results of slope calibraons with conducvity sensor can be viewed by pressing the ‘View’ key in ‘Slope’
calibraon LED mode which returns the current gain on the nominal cell used to compute the displayed
conducvity values.

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Display Features Available Using The ‘View’ Key
• In ‘Node’ mode press ‘View’ key to invoke the node scanning feature (see Instrucons for node scanning and
changing node - page 6).*
• In ‘Baud Rate’ mode press ‘View’ key for 3 to 5 seconds to invoke node changing mode (see Instrucons for
node scanning and changing node - page 6).*
• In ‘Sensor Type’ LED mode, the soware revision for the connected sensor is shown when the ‘View’ key
is pressed.
• In ‘Sensor Type’ LED mode, when ‘Up’ key is pressed then the nominal cell constant of sensor is indicated:
oRange of cell constant is anywhere between K = 0.01/cm up to K= 20.0/cm
• In ‘Sensor Type’ LED mode, when ‘Down’ key is pressed then the currently operang range mode is
displayed.
oPress ‘Up’ key while range mode is displayed to iniate toggling between standard and high range
modes. For the ultralow style sensors only one range mode exists. Press ‘Mode’ to save and exit tog-
gling range modes.
• In ‘Reading’ and ‘Slope’ LED mode the displayed units are mS/cm unless one of the two condions below exists:
oWhen reading is ashing then the units are μS/cm (divide by 1,000 to get mS/cm units)
oWhen the ‘Reading’ or ‘Slope’ LED is ashing then units are Siemens/cm (mulply by 1,000 to get mS/cm)
• In ‘Cal Temp.’ LED mode, the oset in °C * for current temp calibraon is shown when the ‘View’ key is
pressed.
• In ‘Cal Oset’ LED mode, the oset for the dry in air zero calibraon is shown when the ‘View’ key is pressed.
• In ‘Cal Slope’ LED mode, the current gain for the connected DSS conducvity sensor is shown. The limits for
the gain on the nominal cell constant of the given sensor is from 0.300 to 1.700.
oThe calibrated apparent eecve cell constant for the sensor in eld use is obtained by mulplying the
nominal cell constant mes the gain shown as the result of the slope calibraon.
oOutput scaling & limits dened solely based upon the nominal cell constant and range mode in use.
oDays since this calibraon performed shown by holding ‘View’ in the ‘Cal’ mode for 3 to 5 seconds.
If BOTH ‘View’ & ‘Up’ pressed for 3 to 5 seconds in any ‘Cal’ mode will reset all calibraons back to
factory default.
• In ‘Step Change’ LED ‘View’ key displays and toggles TDS units (NaCl, 442, KCl) for std/hi range mode type
sensors.
• In ‘Special’ LED ‘View’ shows salinity in PSU for Std/Hi ranges & resisvity in MegaOhm (MΩ) for ultralow
range.
• In ‘Special’ LED if ‘View’ is pressed for 3 to 5 seconds then total dissolved solids (TDS) in ppt units is shown
for Standard/High ranges and MegaOhm (MΩ) using ultrapure water (UPW) ATC is shown for ultralow range
sensors.
oTo convert from ppt units to the ppm units mulply by 1,000 (i.e. when 3.78 is display this means 3,780 ppm)

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
READ-ONLY Data Core Process Value Descripon READ-ONLY Data Analyc Sensor Value Descripon
Calibrated & Temperature
Compensated Process
Values for DSS-CON(-L)
Conducvity sent as 0 to 50,000
steps for all cell constants & range
modes. To compute conducvity
value sent is mulplied by cell
constant integer (nominal cell * 100)
& range mode scaling factor which
is then nally divided by 50,000 to
yield μS/cm units.
Connected Sensor
Type
1 - DSS-pH
2 - DSS-ORP Standard Range
3 - DSS-ORP Wide Range
4 - DSS-DO (Dissolved Oxygen)
5 - DSS-ISE (Ion Selecve)
6 - DSS-CON (EC Standard/High)
7 - DSS-CON-L (EC Ultralow)
Raw Process Values
Temperature Process Values
Scaling for raw conducvity values
is the same as temperature com-
pensated conducvity values for the
given sensor.
Calibrated temp with the range
-40.0 to +210.0 °C sent as 0 to
2,5000
Sensor Serial Number
Sensor Diagnoscs
Unique Serial Number Designaon:
YY.M-AA.DDD **
Sensor Item Number
Soware Revision
Max Temp in Use
Min Temp in Use
Days in Field Use
Computed units for
DSS-CON(-L)
Computed units of salinity/resisvity
sent as 0-50,000 correspond to
0-50.000 PSU/MΩ
Computed units of total dissolved
solids (TDS) NaCl, 442 or KCl sent
as 0 to 50,000 correspond to 0
to 100,000 ppm. On handheld
communicator the units of ppt are
displayed instead of ppm (1ppt =
1,000ppm
Calibraon Values
Temperature Oset
Days since Temp Oset Cal
Process Oset (Zero Dry in Air)
Days since Process Oset (Zero) Cal
Slope Low Cal
Days since Slope Low Cal
Slope High Cal
Days since Slope High Cal
** Serial format YY is last digits of year; M is month with A=Oct, B= Nov & C=Dec; AA is leer(s) from A to nY (as permissible); DDD is value from 0 to 255
READ/WRITE Type Adjustable Calibraon Descripon READ/WRITE Type Adjustable Parameter Descripon
Oset Adjust Temperature
Calibrated Temperature Value

The temperature to which reading
is adjusted is sent as 0 to 2,500
corresponding to -40.0 to +210.0
°C
Reset Calibraons
Temp. Comp.
Coecient
Will reset all user adjustable sensor
calibraons back to factory default values
Adjustable from 0.00 to 9.99 % per °C as
appropriate for measured sample
Oset to create true zero
for dry in air condion



Dampener
Delay from Boot
Time averaging of process value
Time unl process values are sent from boot
1, 2, 3, 4, 5, 8, 10, 15, 20 or 30 Seconds
Adjust Sensor Slope
Gain on Nomial Cell Constant
Sent as 300 to 1,700 corresponding
to 0.300 to 1.700 mulplier to
nominal cell constant of the sensor
Step Change
Increment value for stepwise calibraon
on the handheld communicator:
0.05, 0.10, 0.20, 0.5, 1.0 or 2.0 % per °C
* Negave values shown as ashing.
.
Note 1: All Modbus devices on network must use the same baudrate and have a unique node address. Handheld Communicator (HFC) is
Modbus master while all DSS sensors are Modbus slaves. To interface HFC with DSS sensor, either removed it from the network, or else bypass
with a bridge box with switch scheme. Access any given DSS sensor on the Modbus network with HFC is possible if the exisng Modbus master
is disconnected or powered down. If node of DSS sensor is not known, use Widows Soware or HFC search feature to nd it. Please see DSS
installaon guide and DSS controller manual for addional recommendaons & details about commissioning, calibraon and troubleshoong.
 Access to READ values in Core Process Value Column gained through Modbus funcon code (04).
Note 3: Access to READ parameters in the Analyc Sensor Value Column, Adjustable Calibraon Column & Adjustable Parameters Column
gained through Modbus funcon code (03).
Note 4: Access to WRITE parameters in the Analyc Sensor Value Column, Adjustable Calibraon Column & Adjustable Parameters Column
gained through Modbus funcon code (16).

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Conducvity Cell Constant and Available Range Modes
for Smart DSS Sensors with RS-485
STANDARD RANGE MODE * - in microSiemens/cm
 
Cell Constant (K) 
   CCCC
0.01 200 0.004 2 200 100 66.67
0.02 400 0.008 4 400 200 133.33
0.05 1,000 0.02 10 1,000 500 333.33
0.10 2,000 0.04 20 2,000 1,000 666.67
0.20 4,000 0.08 40 4,000 2,000 1,333.33
0.50 10,000 0.2 100 10,000 5,000 33,33.33
1.00 20,000 0.4 200 20,000 10,000 66,66.67
2.00 40,000 0.8 400 40,000 20,000 13,333.33
3.00 60,000 1.2 600 60,000 30,000 20,000.00
5.00 100,000 2 1,000 100,000 50,000 33,333.33
10.00 200,000 4 2,000 200,000 100,000 66,666.67
20.00 400,000 8 4,000 400,000 200,000 133,333.33
HIGH RANGE MODE * - in microSiemens/cm


Cell Constant (K) 
   CCCC
0.01 2,000 0.04 20 1000 666.67 500
0.02 4,000 0.08 40 2,000 1,333.33 1,000
0.05 10,000 0.2 100 5,000 3,333.33 2,500
0.10 20,000 0.4 200 10,000 6,666.67 5,000
0.20 40,000 0.8 400 20,000 13,333.33 10,000
0.50 100,000 21,000 50,000 33,333.33 25,000
1.00 200,000 42,000 100,000 66,666.67 50,000
2.00 400,000 84,000 200,000 133,333.33 100,000
3.00 600,000 12 6,000 300,000 200,000.00 150,000
5.00 1,000,000 20 10,000 500,000 3333,33.33 250,000
10.00 2,000,000 40 20,000 1,000,000 666,666.67 500,000
20.00 4,000,000 80 40,000 2,000,000 1,333,333.33 1,000,000
* Sensor can toggle between standard/high range mode range mode while in use. Standard/high range mode sensor is one conguraon and associated
sensor board hardware. Ultralow range mode sensor is a dierent conguraon and associated sensor board. While you can toggle between standard and
high range modes you cannot toggle between the standard/high and ultralow modes since these are two dierent sensor boards. Two slope calibraons are
stored in dual mode standard/high sensors; slope low is used for the standard mode and slope high for the high mode. Slope calibraons are automacally
assigned based upon range mode in use for sensor at me when calibraon is performed. The ultralow range mode only uses the single low slope (slope high
is unused).

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ULTRA-LOW RANGE MODE * - in microSiemens/cm


Cell Constant (K) 
   CCCC
0.01 2 0.00004 0.02 2 1 0.667
0.02 40.00008 0.04 4 2 1.333
0.05 10 0.0002 0.1 10 53.333
0.10 20 0.0004 0.2 20 10 6.667
0.20 40 0.0008 0.4 40 20 13.333
0.50 100 0.002 1.0 100 50 33.333
1.00 200 0.004 2.0 200 100 66.667
2.00 400 0.008 4.0 400 200 133.33
Total dissolved solids (TDS) units are computed from measured conducvity.
The curves that dene relaonship between the measured conducvity
and user selectable total dissolved solid (TDS) units of NaCl, KCl or
442 are preprogrammed into sensor with full range of 0 to 100,000
ppm. The actual usable range may be limited by the choice of cell
constant and range mode in which the sensor is operated.
Other types of total dissolved solids (TDS) for other electrolytes
or electrolyte mixtures can be programmed into the sensor on a
special order basis (minimum order requirements apply for such
special programming requests). Inquire to the factory if you have need
for such special TDS units for your smart digital DSS Modbus RTU
conducvity sensors.
Salinity computed from the measured conducvity. Curves that
dene the relaonship between measured conducvity and the
computed salinity in PSU are preprogrammed into the sensor with a
full range of 0.000 to 50.000 PSU.
The actual supported range may be limited by cell constant and
range mode used). Contact the factory to determine the most suitable
sensor model and cell constant conguraon for your desired salinity
range of interest.
Conducvity Cell Constant and Available Range Modes
for Smart DSS Sensors with RS-485

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The conducvity of pure water varies signicantly with temperature
in a well dened but non-linear fashion as detailed in the graph to le.
This behavior is preprogrammed into the DSS-CON-L Modbus RTU
conducvity sensors for the automac temperature compensaon
feature to make it suitable for ultrapure water (UPW) type applicaons.
Although the recommended cell constant for performing conducvity
measurement in UPW is K=0.01/cm for best resoluon and lower bounds
of measurement there may be situaons where this K=0.01/cm cell
constant cannot be used for the planned installaon locaon because
of limitaons such as piping arrangement and low-ow. The higher cell
constants of K=0.05/cm or K=0.10/cm can be used instead in such cases
albeit they require the sample to be at a higher temperature to ensure
best results. Table below details recommended minimum temperature
for various cell constants for use in UPW. The minimum temperature for
UPW measurement for each cell is determined based upon the lowest
absolute conducvity value for which the cell constant is recommended
& temperature at which this conducvity occurs for UPW. Resisvity
are computed units are the inverse of the measured conducvity value.
Ultralow Range Conducvity Sensors for Ultrapure Water (UPW)
ULTRA-LOW RANGE MODE

Cell Constant (K) Raw Max Input
@ 25°C Resoluon Lowest Recommended Absolute Measurement Minimum Temp °C * Absolute MegaOhm (MΩ) @ Min Recommended °C *
0.01 2 0.00004 0.02 8 50
0.05 10 0.0002 0.1 40 10
0.10 20 0.0004 0.2 55 5
* Minimum recommended temperature is conducvity of UPW which is 1% of ultralow range mode for the given cell and the associated MegaOhm units.
Measurements can be performed below the recommended minimum temperature with an associated higher uncertainty for those situaons.
For ultralow range conducvity sensors the 5th read input register
(30005) sends the computed resisvity MegaOhm (MΩ) using
the user dened linear automac temperature compensaon
(ATC) while the 6th read input register (30006) sends computed
resisvity MegaOhm (MΩ) using the special non-linear ultrapure
water style automac temperature compensaon. The resisvity
values sent as 0 to 50,000 steps corresponding to 0.000-50.000
MegaOhm (MΩ) for both the 5th (30005) & 6th (30006) read
input registers. Theorecal temperature compensated resisvity
value can never go above 18.18 MegaOhm (MΩ) for uncon-
taminated pure water since this is the ideal value at 25 degrees
celsius.
Temperature compenated conducvity and resisvity are refer-
enced back to the 25 °C condion for all ATC. Ultrapure water
with no contaminants has a value of 0.055 μS/cm conducvity
or 18.18 MΩ in resisvity. The most common units for mea-
surement of pure water is resisvity (MΩ) MegaOhm due to high
resoluon and convenient scaling in the very low conducvity
levels. Temperature compensated conducvity and computed
resisvity values sent for the ultralow range mode smart digital
DSS-CON-L style Modbus RTU conducvity sensors as well as
the raw conducvity.
Graph above shows relaonship between the resisvity of pure water
at various temperatures. Computed resisvity MegaOhm (MΩ) units
are the inverse of measured conducvity and so are the mirror image
of the conducvity at various temperatures for ultrapure water (UPW).
The graph above shows absolute raw resisvity at various temperatures.
Resisvity values sent include ATC referencing reading to 25 °C state.