Figure 6: Inserting the self-tapping screws
Figure 7: Location of the integrated screw tabs
Wiring
About this task:
Pull enough wire into the enclosure to reach the terminal
blocks and complete the wiring connection according
to Figure 8 . Make all connections in accordance with
national and local codes.
Important:
Deactivate the 24 VAC or 24 VDC
power supply until you make all connections to the
device to prevent electrical shock or equipment
damage. Follow correct electrostatic discharge (ESD)
handling procedures when you install the device or
equipment damage may occur. Use 14 AWG to 22
AWG shielded wire for all connections. Do not locate
the device wires in the same conduit with wiring
used to supply inductive loads such as motors.
To wire the sensor, complete the following steps:
1. Connect the plus DC or the AC voltage hot side to
the PWR terminal and connect the power supply
common to the COM terminal.
Note:
The device is reverse voltage-protected
and will not operate if you connect it
backwards. The device has a half-wave power
supply so the supply common is the same as
the signal common. Use caution when you
wire multiple devices or when you ground the
secondary of a transformer to ensure that the
circuit ground point is the same on all devices
and on the controller.
2. Check the controller Analog Inputs (AI) to
determine correct connection before you apply
power. Both current and voltage output signals
reference to the COM terminal.
Note:
The current outputs operate in the active
mode and do not require a loop power supply.
The sensor generates the signal current and
you must not connect the outputs to a powered
input or device damage will result.
3. The analog output signals connect directly to
the Building Automation System (BAS) for use as
control parameters. See Figure 9 .
4. If the device includes a BACnet connection, use a
twisted shielded pair to connect to the terminals
marked A-, B+, and SHLD (SHIELD).
5. The positive wire connects to B+, the negative to A-,
and the cable shield connects to the SHLD terminal
on each device. Connect the shield wire to earth
ground at one end of the network only. See Figure
Note:
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
ft (1220 m) and the maximum number of
nodes on one segment length is 128. Nodes
are any device connected to the loop and
include controllers but do not include the EOL
terminators.
To install more than 128 devices, or to increase
network length, requires repeaters for correct
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.
Note:
If you install the device at either end of
an RS-485 network, install an end-of-line (EOL)
termination resistor (121 ohms) in parallel with
the A- and B+ terminals. This device includes
a network termination resistor and jumper to
connect the EOL resistor on the PCB. Move the
jumper to the EOL position and no external
resistor is necessary. See Figure 11.
GS3000 Gas Detection Sensor Series Installation Guide
3