Section 5
ZGARD CX II Controller
Programmable Alarm Relays Operation
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.
Alarm and Control:
There are two basic operating
schemes that can be set up by the controller. The
options described below can be selected by the
user interface keypad located on the front panel.
Default Mode:
The program memory of the
ZGARD CX II controller retains the identification
codes for MSA ZGARD S and GS gas sensors
listed. Each sensor type and operating range
includes pre-selected caution, warning and alarm
thresholds. For instance, if the ZGARD CX II
controller identifies ZGARD S and GS Carbon
Monoxide sensor, then the option of using the
internal codes is available. This feature will accept
the residing threshold of 25ppm (Caution), 35ppm
(Warning) and 50ppm (Alarm), and will be used to
determine the alarm status commands reported by
the controller during operation.
Custom Mode:
The ZGARD CX II controller can be
programmed with custom threshold settings. This
option will bypass the internal digital identification
code of a ZGARD S and GS sensor. The Caution,
Warning and Alarm thresholds can be set to any
value from 1% to 99% of the operating range (Full
Scale) for each individual system sensor.
Zone Feature:
A group of remote sensors can be
assigned to one of 8 Zones by the user. The
ZGARD CX II controller can then execute control
functions based on each zone. By adding optional
Remote Relay Modules (RRM’s) distributed control
can be achieved in addition to the internal control
via the relays inside the ZGARD CX II.
Event Logging Feature:
The ZGARD CX II
controller retains all status change events in non-
volatile memory. A status change event can be
any point going from OK to any alarm state, from
one alarm state to another alarm state or from any
alarm state to OK. All events have a time and
date stamp associated with them. Events may be
reviewed from the LCD screen.
Relay Outputs:
The controller provides a standard
compliment of 4 common relay outputs; each one
configurable to be Caution, Warning., Alarm or
Fault. Additional remote relay modules may be
added anywhere on the RS-485 bus to provide
more intricate local control. Relays only activate if
the sensors in their zone exceed the programmed
threshold levels.
Relay Modes:
Relays set to function as normally
de-energized are inactive under normal condition,
and will be activated during a threshold breach. The
normally energized function forces a relay to be
powered ON during normal conditions and will de-
activate during a threshold breach. This feature is
known as a fail-safe operation. When a relay is
activated, the LED located beside it will be turned
ON. Relays set to the latching function will lock ON
after a threshold breach. The reset button must be
pressed after each condition has cleared in order to
de-activate the relays.
Delay Feature:
The Caution, Warning and Alarm
relays can be set with an OFF delay between 0 to
600 seconds. The OFF delay is common to all of
the gas sensors linked to the controller.
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