Specifications

Multi-Zone Gas Monitors
60 P/N: 3015-5074 Rev 10
NOTE: Refer to the Recommended Alarm Settings & Gas Enumeration table on page 53.
NOTE: Time Structure Format consists of 13 unsigned character types. They are 1
second digit, 10 second digit, 1 minute digit, 10 minute digit, 1 hour digit, 10 hour digit, 1
day digit, 10 day digit, 1 month digit, 10 month digit, 1 year digit, 10 year digit, last byte is
unused.
B.3.11. Alarms and Alarm Acknowledge
The Multi-Zone can be operated in two different alarm acknowledge modes, Auto and Manual (set via the
alarm_ack_mode variable in the system data register). For purposes of this discussion, the term “Alarm”
refers to an MZ state where the alarm light is on and the appropriate alarm relay is activated. The term
“Alarm condition” refers to the external condition (i.e., refrigerant leak) that initially causes the MZ monitor to
go into an alarm. If an alarm occurs it can be handled in one of 3 ways.
1. Non-Latching Mode. This mode is enabled by setting the AUTO_ACK_MODE parameter in the
system register to “1”. In this mode, if an alarm condition occurs an MZ alarm will be created. If the
alarm condition is subsequently removed, the MZ alarm will automatically be cleared by the MZ
monitor when the zone in alarm is sampled “clear”. Note, in this mode of operation, it is possible for
an alarm to occur and be cleared without user or MODBUS master intervention. If this is the case,
the only evidence of the alarm would be contained in the MZ alarm log.
2. Latching Mode with Silence. This mode is enabled by setting the AUTO_ACK_MODE in the
system register to “0”. In this mode, if an alarm condition occurs, an MZ alarm will be created. In
order for the alarm to be removed the MODBUS master will write a “0” to the ALARM parameter in
the ZONE register. This will cause the alarm to be “silenced” in the MZ monitor (i.e., the alarm relays
will return to their normal state and the ALARM lamp will be extinguished). The next time the zone
with the alarm condition is sampled, if the alarm condition still exists, the alarm will be reactivated and
the alarm parameter will be reset to “1” in the MZ. Otherwise, if the alarm condition has cleared, no
further action is required and normal operation will resume.
3. Latching Mode without Silence. This mode is enabled by setting the AUTO_ACK_MODE in the
system register to “0”. In this mode, if an alarm condition occurs, an MZ alarm will be created. The
MZ MODBUS master will then write a “1” to the ALARM ACK parameter in the zone register. The
alarm will continue to persists (i.e., Relays in alarm state and Alarm light on) until the offending zone
is sampled and no alarm condition is detected. At that point, the ALARM ACK parameter is
automatically cleared by the MZ monitor, as is the ALARM parameter.
NOTE: If the ALARM ACK parameter is set to “1” and the ALARM CONDITION is
upgraded (from leak to spill, or spill to evacuate) the ALARM ACK parameter will
automatically be cleared to “0” by the MZ.
B.3.12. Date Time Register 0x0015 (21 Dec) (R/W, 14 Bytes)
Variable Type Length Description
Date_Time Time 14 bytes
Contains current time and date. Structure is defined as in note 2 of
zone data
Time Structure Format consists of 14 unsigned character types. They are 1 second digit, 10 second digit, 1
minute digit, 10 minute digit, 1 hour digit, 10 hour digit, a day digit, 10 day digit, 1 month digit, 10 month digit,
1 year digit, 10 year digit, day of the week, last byte is unused.