Rockwell Automation T3419 ICS Regent Fire Detector Input - Manual (Page 18)

Fire Detector Input Modules (T3419)
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Industrial Control Services
LED Force
This is the name used in the application program to control
the ALARM indicator for the input on the face of the input
module. In some applications it is desirable to latch the alarm
indication for the input after a fire detector has alarmed and
then reset the indication after a fire detector reset has
occurred. By naming the LED Force bit, you can control the
ALARM indicator through application programming. If
desired, name the LED Force bit, using up to 12-characters.
Programming
Inputs are referenced in the application program through the
tag names defined in the I/O Configuration Editor. When the
fire detector is in the alarm state the input is said to be on, or
have a value of one. In ladder logic, the on state would
produce power flow in a normally open (N.O.) contact.
Field wiring open circuit or short circuit conditions are
referenced in the application program using the Fault Name
tag names defined in the I/O configuration Editor. If there is
a short or open circuit the Fault Name status is off.
Resetting a Latched Fire Detector
Most typical fire detector input sensors latch when tripped
and need to be reset. A sensor reset occurs when the supply
voltage to the detector is removed. The fire detector input
module provides individual channel reset capability designed
for this purpose. Through application programming, a Reset
bit for each input can be turned on to reset the desired input
channel. When the module receives an input reset signal, the
power to the input circuit is turned off. The front panel alarm
LED will go off and the inputs state reported to the processors
shall remain unchanged. The module will indicate a line fault
for the input (since the loop current is zero with the power
removed).
When the reset signal is turned off, power is applied to the
input and the status LED will report the field input state.
However, the input state reported to the processors will
remain in its last state for an additional period (typically 5
seconds) to all the fire detector to settle. After this delay the
actual field signal shall be reported back to the processors.