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Editing MHI Databases
2.8.10 Bell Cutoff
Bell Cutoff is the length of time the bells sound before they are automatically silenced by the
panel. A time of 0 disables this feature. The cutoff can be set from 5 to 30 minutes. If the cutoff
is used, it must be longer than the Bell Timeout.
For UL installations, disable Bell Cutoff.
2.8.11 Coded Bell Speed
Coded Bell Speed sets the time interval between the bits of the codes. This speed can be 1,
¾, ½ or ¼ second. The time between digits is three times this speed. The time between
rounds is seven times this speed. Note that a minimum of three rounds of coded bells is
required per NFPA 72.
2.8.12 Maintenance Margin
Maintenance Margin sets the gap between the maintenance threshold and the alarm threshold
for addressable sensors. If the sensor stays between these two values for the Maintenance
Retard time, the panel reports a Maintenance Alert trouble for the sensor. The margin can be
set from 0 to 500, with 0 giving no warning and 500 giving the earliest warning.
2.8.13 Maintenance Retard
Maintenance Retard is the number of consecutive scans the addressable sensor has to stay
between the maintenance and alarm thresholds to generate the Maintenance Alert trouble.
This retard can be from 5 to 50 scans. Scan time can vary from 2.5 to 5 seconds with usual
values from 3.5 to 4 seconds.
2.8.14 Enable Disconnect and Test Timeout
Enable Disconnect & Test Timeout enables or disables disconnect timeouts. If the timeouts
are disabled, Relay Disconnect, Disconnect, Signal Disconnect, Common Disconnect and
Test Mode must all be manually ended. If enabled, these functions are automatically ended
after four hours.
2.8.15 Suppress Missing Signals
Suppress Missing Signals allows for the suppression of device missing signals for a loop that
has a short or ground fault condition. If enabled, the panel only reports the short or ground
fault condition, but not the missing device messages.
2.8.16 Hot Keys
Hot Keys are a set of drop down boxes that allow you to set the functions of the operator keys
on the front of the panel. There are 8 keys, each with red and green LED (some keys may
have yellow instead of red LEDs). The LEDs are used to display function status. Figure 11
shows the panel with the label NP-4918.
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