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WIRING
Deactivate the 24 Vac/dc power supply until all connections are made
to the device to prevent electrical shock or equipment damage.
Follow proper electrostatic discharge (ESD) handling procedures
when installing the device or equipment damage may occur.
Use 22 AWG shielded wiring for all connections and do not locate the
device wires in the same conduit with wiring used to supply inductive
loads such as motors. Connect the cable shield to ground at the
controller only. Make all connections in accordance with national and
local codes.
Connect the 24 Vac/dc power supply to the terminals labeled POWER
and COMMON. Use caution if 24 Vac power is used and one side of
the transformer is earth grounded. In general, the transformer should
NOT be connected to earth ground when using devices with RS-485 network connections. The device is
reverse voltage protected and will not operate if connected backwards.
Connect the RS-485 network with twisted shielded pair to the terminals marked A(-), B(+) and SHIELD.
The positive wire connects to B(+) and the negative wire connects to A(-) and the cable shield must be
connected to the SHIELD terminal on each device. If the device is installed at either end of an RS-485
network, and end-of-line (EOL) termination resistor (121 Ω) should be installed in parallel to the A(-) and
B(+) terminals. This device includes a network termination jumper and will connect the (121 Ω) resistor
correctly on the PCB. Simply move the jumper to the EOL position and no external resistor is required. The
ground wire of the shielded pair should be connected to earth ground at the end of the network and the
master is not grounded. Do not run bus wiring in the same conduit as line voltage wiring or other wiring
that switches power to highly inductive loads such as contactors, coils, or motors.
A network segment is a single shielded wire loop run between several devices (nodes) in a daisy chain
configuration. The total segment length should be less than 4000 feet (1220 meters) and the maximum
number of nodes on one segment length is 64. Nodes are any device connected to the loop and include
controllers but do not include the EOL terminators. To install more than 64 devices, or to increase network
length, repeaters will be required for proper communication. The maximum daisy chain length (segment)
depends on transmission speed (baud rate), wire size and number of nodes. If communication is slow or
unreliable, it may be necessary to wire two daisy chains to the controller with a repeater for each segment.
An optional signal is the relay output available on the N. OPEN and RELAY COM terminals. The RELAY COM
terminal is NOT connected to the power supply COMMON terminal. The relay output is completely isolated
and has a Normally Open (NO) signal. This signal can be used to directly control an alarm or ventilation fan.
SET-UP
The device parameters must be set before connection to the network and will ensure each device will have
a unique MAC address and Device Instance for start-up. On start-up, the MAC address is appended to the
Device Object: Vendor Identifier to create the unique Device Instance (Device Object : Object Identifier).
Once connected to a network, the Device Object : Object Identifier can be written to any unique value via
BACnet® and then the MAC address will no longer be appended to the value. Once set, all parameters are
saved in non-volatile memory. The local menu and LCD are used to set the BACnet® MAC device address
(0-127) and the baud. The menu and set-up procedure is described in the Start-up section.
Figure 5
Figure 6
Building Controller
Device 01
Device 02
Device 03
Set EOL Jumper
Connect Shield
One End Only
Power
COMMON
Power
COMMON
Power
COMMON
A(-)
B(+)
SHLD
A(-)
B(+)
SHLD
A(-)
B(+)
SHLD
BACnet® Master
24 Vac / dc
Common
A(-)
B(+)
Shield
EOL
DOWN
A-
B+
SHIELD
COMMON
POWER
UP
SAVE
MENU
N. OPEN
RELAY COM
RELAY
CO2 SENSOR
0001246
EOL
IN-GE-CDD3A1XXXBAC-03
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