Specifications

Ammonia Gas Monitor – Multi Zone
Instruction 3015-5113 53
Zone Data Register 0x12xxh R/W 78 bytes
Each zone for an AGM-MZ has a separate Zone data structure that is 78 bytes long. The zone number is the
low order byte in the register address (i.e., Zone 1 data register = 0x1201h)
Variable Type Length Description
Location C 13 bytes 13 byte array, Alpha Numeric Description or Name of Zone
Flow OK UC 1 byte
Status of Flow check. Value of 1 indicates flow check is good.
DO
NOT MODIFY
Gas Type UC 1 byte See note 1 Below (DEFAULT = R134a)
Distance UI 2 bytes Zone Tubing Length (in feet) (DEFAULT = 100 feet)
Zone Temp I 2 bytes
Avg temp at zone (degrees C) (DEFAULT = 25
C)
Concentration Float 4 bytes
Last Measured concentrations (uM/L)
DO NOT MODIFY
Concentration2 Float 4 bytes
Last Measured concentration (PPM)
DO NOT MODIFY
Alarm Ack UC 1 bytes
Set value to 1 to acknowledge Alarm.
NOTE: AGM-MZ will reset this
byte to 0 when the Alarm byte (below) is = 0 and zone in alarm is
sampled. If the alarm condition/byte increases (leak>>spill or
spill>>evac) the AGM-MZ will also reset this byte to 0
Alarm UC 1 bytes Alarm Status; 0 = no alarm, 1 = leak; 2 = spill; 3 = evac.
Leak Level UI 2 bytes Level to trigger a leak alarm (in PPM) (DEFAULT = 100)
Spill Level UI 2 bytes Level to trigger a spill alarm (in PPM) (DEFAULT = 300)
Evac Level UI 2 bytes Level to trigger a evacuate alarm (in PPM) (DEFAULT = 500)
Peak PPM UI 2 bytes Highest Recorded PPM in zone
Peak Time TIM 13 bytes Date an time of highest peak (see note 2 for format)
Alarm Time TIM 13 bytes Date and time of last alarm (see note 2 for format)
Not Used 13 bytes
Log Interval UI 2 bytes Number of minutes between Log entries (DEFAULT = 1440)
NOTE 1: Refer to the Recommended Alarm Settings & Gas Enumeration table on page 47.
NOTE 2: 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.
Alarms & Alarm Acknowledge
The AGM-MZ 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 a AGM-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., ammonia leak) that initially causes the AGM-MZ 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 AGM-MZ alarm will be created. If
the alarm condition is subsequently removed, the AGM-MZ alarm will automatically be cleared by the
AGM-MZ 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 AGM-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 AGM-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