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Copyright HK Instruments 2021

www.hkinstruments.fi

Installation version 7.0 2021

INSTALLATION

INSTRUCTIONS

CARBON DIOXIDE TRANSMITTERS

CDT-MOD-2000 Series

•  READ THESE INSTRUCTIONS CAREFULLY BEFORE 

ATTEMPTING TO INSTALL, OPERATE OR SERVICE THIS 
DEVICE.

•  Failure to observe safety information and comply with 

instructions can result in PERSONAL INJURY, DEATH AND/OR 

PROPERTY DAMAGE.

•  To avoid electrical shock or damage to equipment, disconnect 

power before installing or servicing and use only wiring with 
insulation rated for full device operating voltage.

•  To avoid potential fire and/or explosion do not use in potentially 

flammable or explosive atmospheres.

•  Retain these instructions for future reference.
•  This product, when installed, will be part of an engineered 

system whose specifications and performance characteristics 
are not designed or controlled by HK Instruments. Review 
applications and national and local codes to assure that the 
installation will be functional and safe. Use only experienced and 
knowledgeable technicians to install this device.

Thank you for choosing an HK Instruments CDT-MOD-2000 series 
carbon dioxide transmitter. The CDT-MOD-2000 series is intended 
for  use  in  commercial  environments  in  HVAC/R  applications.  The 
CDT-MOD-2000 series measures carbon dioxide (CO

2

), utilizing the 

industry  standard  NDIR  measurement  principle,  and  temperature 
(T). Optional relative humidity (rH) measurement is also available in 
the same device. The CDT-MOD-2000 series devices are available 
with large touchscreen display making the configuration of the de-
vice quick and easy. Configuration is also possible via Modbus net-
work.

The CDT-MOD-2000 series transmitters calibrate themselves auto-
matically using ABC

TM

 logic. The ABC

TM

 logic requires that the space 

in which the transmitter is used needs to to be unoccupied for four 
hours  per  day  so  that  the  indoor  CO

2

  concentration  drops  to  the 

outside level. CDT-MOD-2000-DC is a dual channel model with a 
measuring channel and a reference channel that makes a continuous 
comparison and the necessary adjustment accordingly. CDT-MOD-
2000-DC is also suitable for buildings that are continuously occu-
pied.

•  humidity in various industrial applications
•  temperatures in HVAC/R environment
• CDT-MOD-2000-DC series devices can also be used in applications 

where there is a constant source of carbon dioxide present (for 
example hospitals and greenhouses)

SPECIFICATIONS

Performance

Measurement ranges:

CO

2

: 400–2000 ppm

Temperature: 0...50 °C

Relative humidity: 0–100 %

Accuracy:

CO

2

: ±40 ppm + 2 % of reading, DC model: 75 ppm or 10 % 

of reading (whichever is greater)

Temperature: <0.5 ºC

Relative humidity: ±2...3 % at 0...50 °C and 10–90 % rH

Total error band includes accuracy, hysteresis and

temperature effect over 5...50 °C and 10–90% rH.

Technical Specifications

Media compatibility:

Dry air or non-aggressive gases

Measuring units:

ppm, °C and % rH

Measuring element:

CO

2

: Non-dispersive infrared (NDIR)

Temperature:

 

Pt1000 (models without rH-measurement)

 

         Integrated (models with rH-measurement)

Relative humidity: Thermoset polymer capacitive sensing 

element

Calibration:

 

Automatic self-calibration ABC Logic

TM

 or continuous 

comparison (DC)

Environment:

Operating temperature: 0...50 °C

Storage temperature: -20...70 °C

Humidity: 0 to 95 % rH, non condensing

Physical

Dimensions: 

Case: 99 x 90 x 32 mm

Weight: 

150 g

Mounting: 

3 screw holes slotted, 3.8 mm

Materials: 

Case: ABS

Protection standard: 

IP20

Display (Optional)

Touchscreen

Size: 77.4 x 52.4 mm

Electrical connections:

Power supply:  

 

5-screw terminal block

 

(24 V, GND) 

 

0.2–1.5 mm

2

  (12–24 AWG)

Relay out:  

 

3-screw terminal block

 

(NC, COM, NO)

 

0.2–1.5 mm

2

  (12–24 AWG)

Electrical

Input:   24 VAC or VDC, ±10 %

 

Current consumption: max 90 mA (at 24 V) +  

 

10 mA for each voltage output or 20 mA for  

 

each current output

Relay out: 

 

SPDT Relay, 250 VAC / 30 VDC / 6 A

 

Adjustable switching point and hysteresis

One analog output for selected media:

0/2*–10 VDC, Load R minimum 1 kΩ

*(2–10 VDC display models only)

 or

4–20 mA, maximum load 500 Ω

Communication

Protocol: MODBUS over Serial Line

Transmission Mode: RTU

Interface: RS485

Byte format (11 bits) in RTU mode:

 

Coding System: 8-bit binary

 

Bits per Byte:

 

 

1 start bit

 

 

8 data bits, least significant bit sent  

 

 

first

 

 

1 bit for parity

 

 

1 stop bit

Baud rate: selectable in configuration

Modbus address: 1−247 addresses selectable in

configuration menu

Conformance

Meets requirements for CE marking:

EMC Directive 2014/35/EU

RoHS Directive 2011/65/EU

LVD Directive 2014/35/EU

WEEE Directive 2012/19/EU

INTRODUCTION

APPLICATIONS

WARNING

CDT-MOD-2000 series devices are commonly used to monitor:

•  CO

2

 and humidity levels in offices, public spaces, meeting rooms 

and classrooms

•  CO

2

 levels of return air in ventilation systems

•  incoming air and return air humidity levels in ventilation system

COMPANY WITH

MANAGEMENT SYSTEM

CERTIFIED BY DNV GL

= ISO 9001 = ISO 14001 =

RoHS 2

2011/65/EU

Summary of Contents for CDT-MOD-2000 Series

Page 1: ...where there is a constant source of carbon dioxide present for example hospitals and greenhouses SPECIFICATIONS Performance Measurement ranges CO2 400 2000 ppm Temperature 0 50 C Relative humidity 0 100 Accuracy CO2 40 ppm 2 of reading DC model 75 ppm or 10 of reading whichever is greater Temperature 0 5 ºC Relative humidity 2 3 at 0 50 C and 10 90 rH Total error band includes accuracy hysteresis ...

Page 2: ...a with good ventilation and an average temperature where it will be responsive to changes to the room conditions The CDT MOD should be mounted on a flat surface Do not locate the CDT MOD where it can be affected by Direct sunlight Drafts or dead areas behind doors Radiant heat from appliances Concealed pipes or chimneys Outside walls or unheated uncooled areas 2 Use the device as a template and ma...

Page 3: ...put 0 2 10 V 4 20 mA output Figure 2b Wiring diagram Power input signal output Wires can be routed through the square opening in the back plate Wires can be routed through the top knockouts Wires can be routed through the bottom knockouts Figure 2d Wiring diagram Relay NC COM NO STEP 2 WIRING DIAGRAMS NOTE When using long connection wires it may be necessary to use a separate GND wire for voltage ...

Page 4: ...0 0 90 0 3x0009 TE high limit 16 bit 50 500 5 0 50 0 C 3x0010 TE low limit 16 bit 0 450 0 45 0 C 3x0011 Parameter for relay 16 bit 0 3 0 CO2 1 rH 2 TE 3 Off 3x0012 CO2 relay on 16 bit 500 1950 500 1950 ppm 3x0013 CO2 relay off 16 bit 450 1900 450 1900 ppm 3x0014 rH relay on 16 bit 15 990 1 5 99 0 3x0015 rH relay off 16 bit 10 985 1 0 98 5 3x0016 TE relay on 16 bit 15 490 1 5 49 0 C 3x0017 TE relay...

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