GASMAX II + GDS-IR Operation & Maintenance Manual, Revision 1.1
Page 26
the sensor value drops below zero. However, negative sensor outputs will always cause the Fault alarm to
trip. The 4-20mA output always locks at 4mA when the reading drifts negative.
TEMP COMPENSATION
adjusts sensor output based on ambient temperature. GDS Corp temperature
compensated sensors are preprogrammed with the necessary table of values and are automatically
uploaded to the GASMAX II from the smart sensor. This menu item is not accessible unless a temperature
compensated local Smart Sensor is installed.
BACKUP CONFIG
allows users to store the entire current GASMAX II menu database into non-volatile
memory for restoration later if incorrect values are accidentally entered or uploaded.
RESTORE CONFIG
restores the GASMAX II menu database to the values from the most recent Backup
Config. This menu item is only available if a smart sensor is not installed. The special keystroke sequence
of 4 consecutive UP keys is also required to perform backup and restore operations.
UPLOAD SENSOR DATA
allows the user to manually upload the entire smart sensor database to the
GASMAX II from the smart sensor.
CAL MARKER
allows the user to set the 4-20mA output value that is transmitted during ZERO and SPAN
calibration. This setting is limited to between 2ma and 20mA and is a useful way to indicate to a GDS
controller that the unit is in CAL MODE.
TX SENSOR LIFE
causes the GASMAX II 4-20mA output to transmit a
“
sensor life
”
value after the
completion of a successful calibration cycle. During normal operation, the GASMAX II transmits a 4mA
signal during the CAL PURGE delay to allow time for the span gas to dissipate. With TX Sensor Life = YES,
the GASMAX II transmits 4mA for the first 10 seconds, then for 5 seconds transmits a value between 4mA
and 5mA, with 4mA equal to 0% sensor life and 5mA equal to 100% sensor life (see Figure 5-5). The
output then returns to 4mA for the remainder of the CAL PURGE delay. For example, if after a calibration
sensor life is 75%, the GASMAX II transmits 4.75mA during the 5-second interval
.
NOTE:
TX SENSOR LIFE SHOULD ALWAYS BE SET FOR
NO
UNLESS THE 4-20MA RECEIVER IS CAPABLE OF
INTERPRETING THE SENSOR LIFE SIGNAL. MOST GDS CORP
PROTECTOR
SERIES CONTROLLERS INCLUDE
THIS CAPABILITY.
Figure 7-3: Sensor Life Transmission Format
