30
© 2020 All rights reserved. Data subject to change without notice.
cGas Detector Digital Transmitter - Installation Manual
Rev. A | 2020.03
All wiring should be run in EMT (or better) conduit properly earth grounded. All
communications (network) wiring must be in shielded cabling. Wire shielding
must be connected together at each device and taped off so it cannot cause
a short on the circuit board when the door is closed. The wiring shield should
be connected to ground only at the controller, have a contiguous connection
throughout the network and be left taped and fl oating at the last device in the
network. The recommended 4 conductor, 16 AWG, shielded stranded wire cable
types are AlphaWire 79220, Belden 5202FE 008500 or equivalent.
To ensure robust data communications, a daisy chain wiring confi guration
must be used. No tee taps. No star confi gurations. This means, four wires run
from one end of the digital network to the other, through the same connections
along the entire run. From one digital device to the next digital device, A goes to
A; B goes to B; GND goes to GND; 24V goes to 24V. Do not mix up the individual
wires or the two groups of four wires.
An end of line jumper must be installed at both ends of the digital network. To
terminate, you must place a 120 ohm resistor on the IN (or sometimes labelled
EN) termination jumper position ON the TERM jumper bank on the FIRST
DIGITAL DEVICE (which might not be the Controller) and the LAST DIGITAL
DEVICE in the wire run. The termination resistor jumper on all other digital
devices in the network should be in the disabled position. Every CETCI digital
device has a termination resistor jumper. The factory default setting of the
termination resistor on all digital devices disabled.
The wiring should be 4-conductor shielded 16 awg stranded within conduit
in a network wiring (daisy-chain) confi guration. Suggested 4-conductor, 16
AWG, shielded stranded wire cable types are AlphaWire 79220, Belden 5202FE
008500 or equivalent.
Wiring Example: 4-Wire VAC
If the cGas Detector is being connected to a BAS, DDC or other control panel
then either a 24 VDC power supply or 24 VAC Class 2 or better transformer
needs to be used.
