Dwyer Instruments CDTA-2E000, CDTA-2N000, CDTA Series, CDTA-2N000-LCD, CDTA-2E000-LCD Installation And Operating Instructions Manual

Series CDTA Communicating Carbon Dioxide Detector

1.10

[71.12]

[92.72]

[90.42]

®

Specications - Installation and Operating Instructions

1.08

[27.33]

4.50

3.65

[114.30]

Bulletin AQ-CDTA-QS

[27.96]

European style North American style

The Series CDTA Communicating Carbon Dioxide Detector combines the function
of three room sensors into a single, compact housing. Parameters include carbon
dioxide, humidity, temperature, and temperature set point with override. By having

eld selectable Modbus® and BACnet Communications, only four wires are needed

for power and the communication signal. The communicating detectors can be daisy­chained together to further reduce installation cost. In order to reduce the set up time,

the RS-485 MAC address is set up using on board dip switches. A second set of
dip switches are used to select whether output is Modbus® RTU or BACnet MS/TP

communication protocols and to limit access to the set up menu.

Like our Series CDT Carbon Dioxide Transmitter, the Series CDTA uses a Single
Beam Dual Wavelength Non-Dispersive Infrared (NDIR) sensor to measure the carbon

dioxide level. This technology can be used in installations that will be occupied 24

hours per day. For improved accuracy, the transmitter can be eld calibrated to the
environmental conditions of the installation. Also, the barometric pressure can be

programmed to correct for altitude. The humidity uses a capacitive polymer sensor and

the temperature is measured using a 10KΩ thermistor sensor. The humidity sensor is
eld replaceable without the need for additional calibration.

Optional local and remote displays are available to display any of the parameters. For

applications in which the building occupants aren’t familiar with CO
the LCD can be programmed to display temperature, humidity, or temperature set

point instead.

Installation

CAUTION

Make sure all connections are in accordance with the job wiring diagram and in
accordance with national and local electrical codes. Use copper conductors only.

Disconnect power supply before installation to prevent electrical

shock and equipment damage.

2 concentrations,

3.56

SPECIFICATIONS
Sensor (CO

Temperature: Solid state band gap.
Range: CO
100% RH; Temperature: 32 to 122°F (0 to 50°C).
Accuracy: CO
±1°C @ 25°C.

Temperature Dependence (CO
Non-Linearity (CO
Pressure Dependence (CO
Response Time (CO
Temperature Limits: 32 to 122°F (0 to 50°C).
Humidity Limits: 10 to 95% RH (non-condensing).

Power Requirements: 10 to 42 VDC / 10 to 30 VAC.
Power Consumption: Average: 0.5 watts; Peak: 1.2 watts.

Output: 2-wire RS-485, Modbus

Weight: 4.4 oz (125 g).

Agency Approvals: BTL, CE.

2): Single-beam, dual-wavelength NDIR; Humidity: Capacitive polymer;

2: 0 to 2000 or 5000 PPM CO2 (depending on model); Humidity: 0 to

2: ±40 ppm ±3% of reading; RH: ±2% (10 to 90% RH); Temperature:

2): 16 ppm.

2): 2 minutes for 99% step change.

2): ±8 ppm / °C at 1100 ppm.

2): 0.13% of reading per mm of Hg.

®

RTU or BACnet MS/TP communication protocol.

2.80

Use electrostatic discharge precautions (e.g., use of wrist straps)

during installation and wiring to prevent equipment damage.

For optimal performance, self calibration feature of the transmitter
requires exposure to normal outdoor equivalent carbon dioxide

Avoid locations where severe shock or vibration, excessive

moisture or corrosive fumes are present.

Do not exceed ratings of this device, permanent damage not

covered by warranty may result.

Upon powering the transmitter, the rmware version will ash on
the display. A warm up period of 30 minutes is required for the

2 concentration.

NOTICE

NOTICE

level once every thirty days.

NOTICE

NOTICE

NOTICE

transmitter to adjust to the current CO

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Modbus® is a registered trademark of Schneider Automation, Inc.

Phone: [phone]

Fax: [phone]

www.dwyer-inst.com

e-mail: [e-mail]

Figure 3 shows how to connect the CDTA in a network containing individual local

COMMON POWER SUPPLY

TO

NEXT

LOCAL POWER SUPPLY

TO

SUPPLY

NEXT

supplies. Use a cable containing a twisted pair and a single conductor. The pair is to
be used for B(+) and A(-). The single conductor is to be used for common. Both AC and
DC supplies are suitable for this conguration.

In either conguration you must use shielded cable. Connect the shield to earth ground

at one location only to prevent ground loops.

All devices in the network should be daisy chained. Star connections and T connections

are not permitted.

The B(+) and A(-) lines must be terminated at both ends with a 120 ohm resistor. If the
CDTA is an end device it has an on-board resistor that may be used. See DIP SWITCH
SETTINGS to enable it.

Figure 1: Removal of cover from back plate

MOUNTING

1. Push tab on top and bottom of cover and lift cover from back plate (See Figure 1).

2. Select the mounting location, away from diffusers, lights or any external inuences.

3. Mount transmitter on a vertical surface to a standard electrical box using the two #6
M2C type screws provided.

4. Pull wires through sub base hole and make necessary connections.

5. Reattach cover to base plate.

WIRING

NOTICE

Wiring should comply with Electrical Characteristics of Generators
and Receivers for Use in Balanced Digital Multipoint Systems, TIA/

EIA-485-A-1998, Telecommunications Industry Association, 1998.

BACnet installations should comply with ANSI/ASHRAE Standard 135-2010 BACnet
A Data Communication Protocol for Building Automation and Control Networks,
American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 2010.

®

installations should comply with Modbus® Communication Protocol over

Modbus
Serial Line Specication and Implementation Guide V1.02, Modbus

®

Organization,

Inc., 2006

Communications wiring must be in a daisy-chain fashion. Star connections are not

permitted.

Cable shield must be connected to earth ground at one location only.

PWR COM B(+) A(-)

PREVIOUS

DEVICE

PWR
COM

B(+)
A(-)

1 2 3 4

TO

DEVICE

PWR
COM

B(+)

A(-)

Figure 2

Figure 2 shows how to connect the CDTA in a network containing a common power
supply. Use a cable containing two twisted pairs. One pair is to be used for B(+) and A(­). The other pair is to be used for power and common. This conguration is not suitable
for AC supplies. Use a DC supply only. Care should be taken that there are not too

many devices powered from the same supply as voltage drops will occur in the wiring.

If you have many devices, or have long cable runs, the local supply conguration may

be a better choice.

Dip Switch Conguration

ON

1 2 3 4 5 6 7 8

Figure 4: Dip switch SW2 (center-left)

Use DIP Switch SW2 (see Figure 4) to congure the RS-485 MAC address of the
device. A valid address depends on the protocol selected. Valid BACnet addresses
range from 0 to 127. Valid Modbus

®

addresses range from 1 to 247. By default, the

device is shipped with BACnet selected and the address set to 127 (as shown in
Figure 4). A valid and unused address should be set before connecting to an existing
network. The device will not function properly if an invalid address is set. During the
power up sequence, the LCD (if present) will display the RS-485 address as the
primary value with “ADR” as the primary text and either “BAC” to indicate BACnet
or “MOD” to indicate Modbus

®

as the secondary text. If the RS-485 MAC address is

invalid, the invalid value is shown as the primary value with “ERR” as the primary text.

PROTOCOL RESERVED

ON

1 2 3 4

MENU ENABLE NETWORK TERMINATION

Figure 5: Dip switch SW1 (bottom-center)

Use DIP Switch SW1 (see Figure 5) to congure other hardware and software options.

Switch ON OFF
1 - Menu Enable

2 - Protocol

Access to the setup

menu is enabled.

Modbus

Access to the setup

menu is disabled.

BACnet

3 - Reserved
4 - Terminating

Resister

120Ω Between A (-)
and B (+)

Open

PWR COM B(+) A(-)

PREVIOUS

DEVICE

COM

B(+)
A(-)

1 2 3 4

POWER

Figure 3

TO

DEVICE

COM

B(+)

A(-)

Dip switch

SW2

Dip switch

SW1

Internal view of transmitter

Figure 6

OVERRIDE BUTTON
PRESSED INDICATOR

PRIMARY VALUE

SECONDARY
VALUE

Figure 7: Display layout

SECONDARY TEXT

PRIMARY TEXT

Home Screen Conguration (DSP)

This value controls what information is displayed on the home screen. See table below
for possible values.

Setting Value Primary Value Primary Text Secondary Value Secondary Text
“CH”

CO

2

“PPM”

Relative Humidity

“%”

Concentration

“CT”

CO

2

“PPM”

Temperature

“°C” or “°F”

Concentration

“HT”

Relative

“%”

Temperature

“°C” or “°F”

Humidity

“TS”
“S”
“T”
“H”

Temperature
Set Point
Temperature
Relative

“°C” or “°F”
“°C” or “°F”
“°C” or “°F”
“%”

Set Point

“°C” or “°F”

Humidity

“C”

CO

2

“PPM”

Concentration

Home Screen

The home screen displays up to two parameters during normal operation. The

parameters displayed on the home screen can be changed by the “DSP” setting in

the setup menu.

Set Point

When in the home display, a single press of either the UP or DOWN button will display
the current temperature set point value. Additional presses of the UP or DOWN buttons
will increase or decrease the set point by 1 degree per button depression. Holding the
UP or DOWN button will continuously change the set point value until the button is

released. The set point display will timeout and return to the home screen after 5

seconds of inactivity. At this point the new set point value is stored in non-volatile
memory. The range of the set point value can be congured with “SOH” and “SOL”
values in the setup menu. A display is not required to change the set point value.

Override

When on the home screen or when changing the set point, the override button (middle
button) can be pressed. When the override button is pressed, a snow ake symbol is

displayed momentarily to indicate the button was pressed.

Remote display

port

Override

Up

Down

Side view of transmitter

Figure 8

Accessing Parameter Setup Menu

In order to access the parameter menu, press and hold the UP and DOWN buttons
for 3 seconds. Once in the parameter menu, pressing the UP or DOWN buttons will

cycle through the parameters. To change any of the parameters, press both the up

and down arrow buttons simultaneously. The word SET will display in the lower right
hand corner of the display. The UP or DOWN buttons can be used to change the value
of the parameter. Press both the UP and DOWN buttons simultaneously to store the
values. In order to go back to the home screen, press and hold the DOWN button for
3 seconds.

Units Selection (UNI)

This value controls the units that data is displayed in.

Setting Value Description
“US”

“SI”

US Customary Units (°F, in Hg)
International System Units (°C, hPa)

Set Point Low Limit Temperature (SOL)

This value sets a lower limit on the current set point value. The set point low limit value

is numerical setting that supports continuous change (increment/decrement) by press
and holding of either UP or DOWN button. If the new set point low limit temperature is

higher than the current set point temperature, then the set point temperature will be set
to the new set point low limit temperature.

Default Value Minimum Value Maximum Value Increment
20°C (68°F) 0°C (32°F) Set Point High Limit 1°

Set Point High Limit Temperature (SOH)

This value sets an upper limit on the current set point value. The set point high limit

value is numerical setting that supports continuous change (increment/decrement)
by press and holding of either UP or DOWN button. If the new set point high limit

temperature is lower than the current set point temperature, then the set point
temperature will be set to the new set point high limit temperature.

Default Value Minimum Value Maximum Value Increment
35°C (95°F) Set Point Low Limit 50°C (122°F) 1°

Typical Barometric Pressure (BAR)

This value sets the typical barometric pressure for the location where the device

is mounted. The factory setting is for standard pressure at sea level. Adjusting the

barometric pressure gives a more accurate measurement, especially at higher
elevations.

Default Value Minimum Value Maximum Value Increment
1013 hPa
(29.9 in Hg)

2 Calibration Process (CAL)

CO

677 hPa

(20.0 in Hg

1016 hPa

(30.0 in Hg

1 hPa

(0.1 in Hg)

This value initiates a calibration sequence of the carbon dioxide sensor to a known gas
value. Read the calibration instructions before using this feature.

Relative Humidity Offset (OFH)

This value allows the relative humidity to be adjusted by a xed amount to match

another calibrated measurement. The display shows the current relative humidity
value plus any previous offset value.

Default Value Minimum Value Maximum Value Increment
0% -30% 30% 0.1%

Temperature Offset (OFT)

This value allows the temperature to be adjusted by a xed amount to match another

calibrated measurement. The display shows the current temperature value plus any
previous offset value.

Default Value Minimum Value Maximum Value Increment
0% -30% 30% 0.1%

CO2 Offset (OFC)

This value allows the CO
another calibrated measurement. The display shows the current CO

value plus any previous offset value.

Default Value Minimum Value Maximum Value Increment
0 PPM -500 PPM 500 PPM 1 PPM

Auto Serial Conguration (AUT)

This value enables or disables the automatic baud rate detection. If the device fails

to communicate on the MS/TP bus or the serial conguration is not 8 data bits, no
parity and 1 stop bit, then this value should be set to “OFF”, and the serial congured

manually.

Baud Rate (BAU)

This value provides the selection of the desired serial baud rate. This value is only

visible when the value of AUT is “OFF”.

Setting Value Description
“ON”
“OFF

Parity Selection (PAR)

This value provides the selection of the desired serial parity. This value is only visible

when the value of AUT is “OFF”.

Setting Value Baud Rate (BPS)

9.6 K

19.2 K

38.4 K

57.6 K

76.8 K

115.2 K

Stop Bits Selection (STP)

This value provides the selection of the desired serial stop bits. This value is only

visible when he value of AUT is “OFF”

Setting Value Description
“NON”

“EVE”

“ODD”

Reset To Factory Defaults (RST)

This value, when set to “YES”, will reset all user settings to their default values and
reset the device. This applies to all settings including BACnet writable settings.

Setting Value Description
1
2

2 Concentration to be adjusted by a xed amount to match

2 concentration

Auto baud enabled, assumes 8 data bits, no parity and 1 stop bit
Auto baud disabled, serial baud rate, parity, and stop bits must be

set manually

9600
19,200
38,400

57,600
76,800
115,200

No Parity
Even Parity

Odd Parity

One Stop Bit
Two Stop Bits

Calibrating Sensor

Step 1: Remove the cover as shown in Figure 1.
Step 2: Remove one of the gas nipple covers on the CO
from the gas pressure regulator to the nipple (See Figure 5).
Step 3: Attach the terminal block accessory to the circuit board so that the power wires

line up with terminals 1 and 2. Plug in the power supply to power up the
transmitter.

Step 4: Hold housing so that the sensor is in the vertical plane as shown in Figure 5.
Step 5: Follow the steps in the accessing parameter section to access the calibration
parameter (CAL).
Step 6: Press and hold the Up and Down arrows for 3 seconds.
Step 7: Flow zero reference gas at 0.3 SLPM for 5 minutes.
Step 8: Press and hold the Down button for 0.5 seconds.
Step 9: Flow the full scale reference gas at 0.3 SLPM for 5 minutes.
Step 10: Press and hold the Up button for 0.5 seconds.
Step 11: Exit the parameter menu.
Step 12: Disconnect the power supply from the power source and remove the terminal

block from the circuit board.

Step 13: Remove tubing from sensor and re-attach the gas nipple cover to the sensor.
Step 14: Re-attach the cover to the back plate.

European North American

Figure 9: Calibration

MAINTENANCE/REPAIR

Upon nal installation of the Series CDTA, no routine maintenance is required. The
Series CDTA is not eld serviceable and should be returned if repair is needed. Field

repair should not be attempted and may void warranty.

This symbol indicates waste electrical products should not be disposed

of with household waste. Please recycle where facilities exist. Check with
your Local Authority or retailer for recycling advice.

2 sensor and attach tubing

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

WARRANTY/RETURN

Refer to “Terms and Conditions of Sale” in our catalog and on our website. Contact
customer service to receive a Return Goods Authorization number before shipping the

product back for repair. Be sure to include a brief description of the problem plus any
additional application notes.

Printed in U.S.A. 3/19 FR# 444131-00 Rev. 2©Copyright 2019 Dwyer Instruments, Inc.

Phone: [phone]

Fax: [phone]

www.dwyer-inst.com

e-mail: [e-mail]