Dwyer CDTA User Manual

Series CDTA Communicating Carbon Dioxide Detector

3.65

[92.72]

3.56

[90.42]

1

.08

[

27.33]

4.50

[114.30]

2.80

[71.12]

1

.10

[

27.96]

Specifications - Quick Start Installation and Operating Instructions

European North American

The Series CDTA Communicating Carbon Dioxide Detector combines the

function of three room sensors into a single, compact housing. Parameters include

arbon dioxide, humidity, temperature, and temperature set point with override. By

c

aving field selectable Modbus

h

eeded for power and the communication signal. The communicating detectors

n
can be daisy-chained 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
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 field
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 field 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
concentrations, the LCD can be programmed to display temperature, humidity, or
temperature set point instead.

Installation

CAUTION

Disconnect power supply before installation to prevent electrical
shock and equipment damage.

®

nd BACnet Communications, only four wires are

a

®

RTU or

Bulletin AQ-CDTA-QS

PECIFICATIONS

S
Sensor (CO

Humidity: Capacitive polymer;
Temperature: Solid state band gap.

Range:

C

Accuracy:

CO
RH: ±2% (10 to 90% RH);
Temperature: ±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:

2

Average: 0.5 watts;

Peak: 1.2 watts.
Output: 2-wire RS-485, Modbus
protocol.

Weight: 4.4 oz (125 g).
Agency Approvals: BTL, CE, RoHS.

): Single-beam, dual-wavelength NDIR;

2

O

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

:

2

umidity: 0 to 100% RH;

H

emperature: 32 to 122°F (0 to 50°C).

T

2

: ±40 ppm ±3% of reading;

): ±8 ppm / °C at 1100 ppm.

): 16 ppm.

2

): 2 minutes for 99% step change.

2

2

): 0.13% of reading per mm of Hg.

2

®

RTU or BACnet MS/TP communication

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.

NOTICE

Use electrostatic discharge precautions (e.g., use of wrist
straps) during installation and wiring to prevent equipment

damage.

NOTICE

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

carbon dioxide level once every thirty days.

NOTICE

Avoid locations where severe shock or vibration, excessive
moisture or corrosive fumes are present.

NOTICE

Do not exceed ratings of this device, permanent damage not
covered by warranty may result.

NOTICE

Upon powering the transmitter, the firmware version will flash on
the display. A warm up period of 30 minutes is required for the

transmitter to adjust to the current CO

concentration.

2

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

DWYER INSTRUMENTS, INC.

Phone: [phone] www.dwyer-inst.com

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A. Fax: [phone] e-mail: [e-mail]

igure 1: Removal Of Cover From Back Plate

F

OUNTING

M

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

1

. Select the mounting location, away from diffusers, lights or any external

2

influences.

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.

. Reattach cover to base plate.

5

IRING

W

NOTICE

iring should comply with Electrical Characteristics of

W
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

ACnet A Data Communication Protocol for Building Automation and Control

B

etworks, American Society of Heating, Refrigerating and Air-Conditioning

N
Engineers, Inc., 2010.

®

Modbus
Serial Line Specification and Implementation Guide V1.02, Modbus

installations should comply with Modbus®Communication Protocol over

®

Organization,

Inc., 2006

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

F

upplies. Use a cable containing a twisted pair and a single conductor. The pair is to

s

e used for B(+) and A(-). The single conductor is to be used for common. Both AC

b
and DC supplies are suitable for this configuration.

In either configuration you must use shielded cable. Connect the shield to earth

round at one location only to prevent ground loops.

g

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

A

onnections are not permitted.

c

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

WITCH SETTINGS to enable it.

S

ip Switch Configuration

D

igure 4: Dip Switch SW2 (Center-Left)

F

Use DIP Switch SW2 (see Figure 4) to configure the RS-485 MAC address of the

evice. A valid address depends on the protocol selected. Valid BACnet addresses

d

ange from 0 to 127. Valid Modbus

r

evice is shipped with BACnet selected and the address set to 127 (as shown in

d

®

ddresses range from 1 to 247. By default, the

a

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.

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.

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 configuration 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
configuration may be a better choice.

Figure 5: Dip Switch SW1 (Bottom-Center)

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

Switch
1 - Menu Enable

2 - Protocol

On

Access to the setup
menu is enabled.
Modbus

Off

Access to the setup
menu is disabled.
BACnet

3 - Reserved
4 - Terminating
Resister

120Ω Between A (-)
and B (+)

Open

Dip Switch

SW2

Dip Switch

SW1

Figure 3

Internal View of Transmitter

Figure 6