Section 4
ZGARD CX II Controller
Operation and Features
Note: The ZGARD CX II Programmable Controller
DOES NOT come pre-programmed with any
sensor, relay or alarm setpoint parameters. These
must be field-programmed and verified by trained
and authorized personnel.
Auto Configuration: The ZGARD CX II Controller
will automatically recognize the number of remote
gas sensors that are compliant with the system.
The first screen on the configuration setup menu
prompts the user to decide if the Auto-Configuration
program should be executed. There are 3 options to
choose from. The Full Configuration… finds
sensors and sets all parameters to defaults
including relay assignments. The Add Sensors…
finds new sensors beyond the last active sensor in
the system. The Change Sensors… compares the
gas identification codes of all active sensors and
reconfigures the sensors with the new association.
When either option is chosen, the controller will
start searching for the remote gas sensors residing
on the RS485 data bus network and organizes the
system accordingly.
Programmable Configuration: The Keypad on the
front panel permits the user to program the
controller for customized applications. To prevent
unauthorized access, an entry code must be
entered before the configuration mode is offered.
Remote Sensors: The controller is designed to
host a series of MSA ZGARD S or GS gas sensors
with RS485 digital output. These sensors are
supported on a 2-wire data bus (network). Each
sensor facilitates Address Jumpers used to assign
a digital address code.
Caution Condition: If the gas level measured at
any of the remote sensors or group of sensors
exceeds a predetermined caution threshold, then
the common Caution LED located above the LCD
Screen will indicate a caution event. Relay outputs
can be pre-assigned to activate on the caution
level.
Warning Condition: If the gas level measured at
any of the remote sensors or group of sensors
exceeds a predetermined warning threshold, then
the common Warning LED located above the LCD
Screen will indicate a warning event. Relay outputs
can be pre-assigned to activate on the Warning
level.
Alarm Condition: If the gas level measured at any
of the remote sensors or group of sensors exceeds
a predetermined alarm threshold, then the common
Alarm LED located above the LCD Screen will
indicate an alarm event. The audible alarm will also
sound at this time, pressing the reset button during
an Alarm event will silence the audible device. If a
new Alarm should occur while the gas controller is
already in an Alarm condition, the audible alarm will
sound again; repeatedly pressing the reset button
can silence it. Relay outputs can be pre-assigned to
activate on the Alarm level.
Relay Mode: Each programmable relay can be
configured to operate in the normally de-energized
or normally energized, latching or non-latching
mode and an OFF Delay.
System Diagnostics Feature: If any active remote
device should fail to communicate on the RS485
network, the System OK LED will turn OFF, the
FAULT LED will turn ON and the fail relay will de-
activate. Subject to a communication failure, the
Warning LED will also turn ON and the warning
relays will be activated. Considering that the
warning level of a gas controller system is typically
used as the ventilation index, this feature is
provided as a fail-safe measure to ensure the
surveillance-affected area is ventilated.
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