Sensorex CX20 User manual

pg.1
Operation Manual
CX20 1/8 DIN
Microcomputer Based Conductivity/Resistivity Controller
11751 Markon Drive Garden Grove, CA. 92841 U.S.A.

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CONTENTS
GENERAL INTRODUCTION………………………………………..………....................3
INITIAL INSPECTION……...………………..................................................................3
USING THE SENSOREX MODEL CX20……......................................................................3
A. Mounting procedure.....................................................................................3
B. Front panel....................................................................................................4
C. LCD screen....................................................................................................5
D. Rear connectors...........................................................................................5
E. Measure mode.............................................................................................6
F. Setting mode................................................................................................6
G. Conductivity/Resistivity calibration mode..............................................10
H. Controlling the relays.................................................................................10
ERROR DISPLAY AND TROUBLESHOOTING……………..……….........................11
SPECIFICATIONS……………..………………………………………........................12
WARRANTY……………..………...............................................................................13

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GENERAL INTRODUCTION
Thank you for selecting the Sensorex CX20. The CX20 Conductivity/Resistivity Controller is a
rugged microprocessor based instrument assembled in a watertight 1/8 DIN case, designed
for use in laboratories and process control applications.
The system displays Conductivity / Resistivity or Temperature status in one large LCD screen.
The model CX20 microprocessor performs a self-diagnostic routine every time you turn on
the unit, it will provide you with basic information on the stability of the instrument.
The model CX20 is equipped with 2 control relays. All control relays are programmable and
hysteresis driven.
INITIAL INSPECTION
Carefully unpack the unit and accessories. Inspect for damages made in shipment. If any
damage is found, notify your Sensorex representative immediately. All packing materials
should be saved until satisfactory operation is confirmed.
USING THE SENSOREX CX20 Conductivity/Resistivity TRANSMITTER ERVIEW
A. Mounting Procedure
1. Make a cutout on any panel, with a thickness of 1/16 inch (1.5mm) to 3/8 inch
(9.5mm). Refer to FIG 1
Figure 1
2. Remove the mounting bracket from the controller and insert the controller into the
cutout. Refer to FIG 2.
Mounting Brackets
Figure 2

pg.4
3. Replace the mounting bracket assembly onto the controller and secure the controller
to the mounting panel. Refer to FIG 3.
Panel Mounting brackets
Figure 3
B. Front Panel
The front panel consists of a 4-digit LCD display and 4 keys.
1. [ MODE ] key:
1a. In the Measure mode, this key will switch the display in sequence from Conductivity,
Temperature and back to Conductivity again or from Resistivity, Temperature and back to
Resistivity again.
1b. In the Calibration/Setting mode, pressing this key for five seconds will move you back to the
previous parameter in the case when recalibration / resetting is required.
2. [ UP ] key:
2a. In the Calibration mode, pressing this key will increase the numeral increment. In the Setting
mode, pressing this key will show the next possible option and increase the numeral increment.
2b. In the Measure mode, pressing this key and [ENTER] key at the same time, the unit will enter
the Calibration mode.
3. [ DOWN ] key:
3a. In the Calibration mode,pressing this key will decrease the numeral increment. In the Setting
mode, pressing this key will show the next possible option and decrease the numeral increment.
3b. In the Measure mode, pressing this key and [ENTER] key at the same time, the unit will enter
the Setting mode.
4. [ ENTER ] key:
In any mode where the user can change the settings, pressing this key will save the new settings. If
no change has been made then pressing this key will just lead the user to the next setting.

pg.5
C. LCD screen
HI1 LOW2 HI2 LOW1
uS
CAL
MAN
M
mS
ATC
12 3 456
1098
7
1. Major LCD display.
2. CAL – This icon will be displayed if the meter is in the Calibration/Setting mode.
3. HI1 & LOW1 – These icons, when displayed, indicate relay action and relay number.
4. HI2 & LOW2 –These icons, when displayed, indicate relay action and relay number.
5. MΩ– Unit indicator.
6. Ԩ– Temperature and unit display.
7. uS – Unit indicator.
8. ATC –This icon will be displayed when a temperature probe is connected.
9. MAN –This icon will be displayed if no temperature probe is not connected.
10. mS – Unit indicator
D. Rear connectors
LNE
CELL
100~230VAC Rel 1 Rel2
GND 10k TH
GND
* Specify “L’ = “Live Lead” 100 to 230 VAC Volts and “N” = “Neutral Lead”
1. Connect the AC line to the rear of the instrument. The model CX20 can be used with
100~240V AC at 50/60 HZ. Make sure the EARTH connector is connected to the earth lead
of the AC power line.

pg.6
2. Connect the proper load to the output relays. Make sure that the load does not exceed the
relay rating, 5 Amp at 115VAC and 2.5 Amp at 230 VAC.
【 Note 】 :
(1) Make sure that the power is unplugged before wiring your probes etc.
(2) Make sure you connect the AC power cord to the correct AC terminals. Incorrect
connection may damage the unit permanently.
E. Measure mode
Turning on the unit will always display the Measure mode. This instrument is designed to
provide 2 distinct measurements: Conductivity, Temperature or Resistivity, Temperature.
MODE
mS
ATC ATC
M
ATC ATC
MODE MODE
MODE
or
1. Conductivity – Current conductivity of the solution.
2. Resistivity –Current resistivity of the solution.
3. Temperature – Current temperature of the solution.
【 Note 】 : Pressing [MODE] key in the Measure mode will cycle the display between the two
modes above.
F. Setting mode
Pressing [DOWN] key and [ENTER] key at the same time, the meter will enter into the Setting
mode.
1. Temperature compensation select:
+ENTER
Temperature coefficient select
MAN
CAL
ATC
CAL
ENTER ENTER
Pressing [UP] key or [DOWN] key in this screen will cycle the display between 01
(Thermistor: 10k ohm), 02 (Manual) modes above.

pg.7
Select the preferred temperature compensation mode, press [ENTER] key to save, and
enter the next setting screen.
2. Temperature Coefficient select:
Temperature compensation select
probe Basic cell constant select
ENTER
ENTER ENTER
CAL CAL
Pressing [UP] key or [DOWN] key in this screen will cycle the display between E2.00, E0.00
above.
Select the preferred coefficient, press [ENTER] key to save, and enter the next setting
screen.
3. Probe Basic cell constant select:
Temperature coefficient select
Range select
ENTER
ENTER ENTER ENTER
CAL CALCAL
Pressing [UP] key or [DOWN] key in this screen will cycle the display from C1.00, C0.10 to
C0.01 basic cell constant above.
Select the preferred basic cell constant, press [ENTER] key to save, and enter the next
setting screen.
4. Range select:
Pressing [UP] key or [DOWN] key in this screen will cycle the display from
CF01/0.000~1.999uS/cm, CF02/0.00~19.99uS/cm, CF03/0.000~1.999MΩ,
CF04/0.00~19.99MΩ(Basic cell K is C0.01) or CF01/0.00~19.99uS/cm,
CF02/0.0~199.9uS/cm(Basic cell K is C0.10) or CF01/0.0~199.9uS/cm, CF02/0~1999uS/cm,
CF03/0.00~19.99mS/cm (Basic cell K is C1.00) above.

pg.8
Select the preferred basic cell constant , press [ENTER] key to save, and enter the next
setting screen.
ENTER
ENTER ENTER ENTER ENTER
CAL
Relay 1 HI/LOW select
CAL CAL CAL CAL
ENTER
ENTER ENTER
CAL
CALCAL
Relay 1 HI/LOW select
ENTER
ENTER ENTER ENTER
CAL
CAL CAL CAL
Relay 1 HI/LOW select

pg.9
5. Relay 1 High / Low select:
Range select
Relay 1 set point value
ENTER
ENTER ENTER
HI1CAL CAL LOW1
Pressing [UP] key or [DOWN] key in this screen will cycle the display from HI、LOW
modes above. Select the preferred mode, press [ENTER] key to save, and enter the next
setting screen.
【 Note 】 :See “H. Controlling the relays ” page.
6. Relay 1 set point value :
Pressing [UP] key or [DOWN] key in this screen to
adjust the value, press [ENTER] key to save, and enter
the next setting screen.
7. Relay 1 hysteresis value:
Pressing [UP]
key or [DOWN] key in this screen to adjust the
value, press [ENTER] key to save, and enter the
next setting screen.
8. Relay 2 High / Low select:
Same as “Relay 1 work way select”
Relay 1 Hysteresis value
ENTER
uS
ENTER
CAL
Relay 1 HI/LOW select
Relay 2 HI/LOW select
Relay 1 set point select
ENTER
uS
CAL
ENTER

pg.10
9. Relay 2 set point value:
Same as “Relay 1 set point value”
10. Relay 2 hysteresis value:
Same as “Relay 1 hysteresis value”
G. Conductivity/Resistivity Calibration mode
The model CX20 uses 1-point calibration for conductivity or resistivity.
In the Measure mode, pressing [UP] key and [ENTER] key at the same time to allow the
meter to go to the Conductivity / Resistivity calibration mode.
At the Conductivity / Resistivity calibration mode, the “CAL” icon and a
conductivity/resistivity reading will display. Rinse the conductivity probe in distilled water
and immerse it into the standization solution. Allow temperature reading to stabilize, press
[UP] key or [DOWN] key to change this reading to that of the standization solution value,
then press [ENTER] key to save. Calibration is now completed.
H. Controlling the relays
1. Isolation voltage:
The maximum isolation voltage of the relay output contacts is 1500 VDC. The voltage
differential between the relay output contacts and the load should not exceed 1500 VDC.
2. Output load:
The current through the relay output contacts should not exceed 5 Amp at 115 VAC and
2.5 Amp at 230 VAC in order not to cause permanent damage to the relay contacts. This
rating is specified for resistive loads only.
3. Relay action, relay set point and hysteresis value:
Relay
Action
Effective RELAY-ON Set
Point
Effective RELAY-OFF Set
Point
HI S.P. + (1/2 H.V) S.P. – (1/2 H.V)
LOW S.P. – (1/2 H.V) S.P. + (1/2 H.V.)
S.P. = Relay Set point H.V. = Hysteresis value (Dead Band)
If the relay action is set to HIGH, the relay will turn ON at (Set Point +1/2 Hysteresis ), and will turn OFF at
(Set Point -1/2 Hysteresis ).
If the relay action is set to LOW, the relay will turn ON at (Set Point -1/2 Hysteresis ), and will turn OFF at (Set
Point +1/2 Hysteresis ).
There are two Independent relays the user can bind to the Conductivity or Resistivity mode. The user can
only bind the two relays to one reading mode at a time. The user can change this anytime by changing
option at the setting mode.

pg.11
ERROR DISPLAY AND TROUBLESHOOTING ERVIEW
Conductivity/R
esistivity
Display
Temperature
Display
Display
Mode
Possible cause(s)
[Action(s)]
"OvEr" -
10.0~120.0°C
Measure
mode
Reading is over the specified
range.
[Change range to higher level]
“Undr” -
10.0~120.0°C
Measure
mode
Reading is under user specified
range.
[Change range to lower level]
[Immerse the conductivity probe
into standization solution.]
"OvEr" "OvEr" Measure
mode
a. Temperature > 120.0°C.
[Bring standization solution to
lower temperature.]
[Replace temperature probe.]
b. No temperature sensor.
[Adjust the manual temperature
to -10~120°C.]
"OvEr" “Undr” Measure
mode
a. Temperature < -10.0°C.
[Bring standization solution to
higher temperature.]
[Replace temperature probe.]
b. No temperature sensor.
[Adjust the manual temperature
to -10~120°C.]

pg.12
SPECIFICATIONS
Conductivity/Resistivity:
Basic Cell K Range Resolution Accuracy
0.01 0.000~1.999uS/cm
0.00~19.99MΩ
0.001uS/cm
0.01MΩ
±0.5%FS ± 1
digit
0.01 0.00~19.99uS/cm
0.000~1.999MΩ
0.01uS/cm
0.001MΩ
±0.5%FS ± 1
digit
0.10 0.00~19.99uS/cm 0.01uS/cm ±0.5%FS ± 1
digit
0.10 0.0~199.9uS/cm 0.1uS/cm ±0.5%FS ± 1
digit
1.00 0.0~199.9uS/cm 0.1uS/cm ±0.5%FS ± 1
digit
1.00 0~1999uS/cm 1uS/cm ±0.5%FS ± 1
digit
1.00 0.00~19.99mS/cm 0.01mS/cm ±0.5%FS ± 1
digit
T
emperature -10.0 to 120.0 °C 0.1 °C ±0.3 °C
Cell Constant 0.01, 0.1, 1.0; 2 wire.
Reference Temperature 25.0 °C, factory set.
Temperature Coefficient 2.00 or 0.00%, user selectable.
Temperature sensor Thermistor: 10k ohm at 25 °C,
(User selectable) Manual
Control type Two ON/OFF control
Relay output (Resistive load only) 5A at 115VAC or 2.5A at 220VAC
Keys Audio feedback in all keys
Power: 100VAC to 240VAC , 50/60Hz
Ambient Temperature range 0.0 to 50.0 °C
Case IP65, 1/8DIN case, depth 90mm
Weight 290g

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WARRANTY
Sensorex warrants this product to be free from significant deviations in material and
workmanship for a period of 1 year from date of purchase. If repair or adjustment is
necessary and has not been the result of abuse or misuse, within the year period, please
return-freight-prepaid and the correction of the defect will be made free of charge. If you
purchased the item from our Sensorex distributors and it is under warranty, please contact
them to notify us of the situation. Sensorex Service Department alone will determine if the
product problem is due to deviations or customer misuse.
Out-of-warranty products will be repaired on a charge basis.
RETURN OF ITEMS
Authorization must be obtained from one of our representatives before returning items for
any reason. When applying for authorization, have the model and serial number handy,
including data regarding the reason for return. For your protection, items must be carefully
packed to prevent damage in shipment and insured against