Emerson Rosemount 975MR, Reference Manual

Page: 21 / 74

Table 1-11: Output Signals vs. Detector State
Detector state LED indicator LED mode Alarm relay Auxiliary relay Fault relay mA output
Normal Green 1 Hz Off Off On 4 mA
Warning Red 2 Hz Off On
(1)
On 16 mA
Alarm
(2)
Red Constant On On On 20 mA
Latch
(3)
Red Constant On Off On 20 mA
On
(1)
On 20 mA
BIT Fault
(4)
Yellow 4 Hz Off Off Off 2 mA
Warning at BIT
Fault Red 2 Hz Off On
(1)
Off 16 mA
Alarm at BIT
Fault Red Constant On On Off 20 mA
Fault Yellow 4 Hz Off Off Off 0 mA
(1) The auxiliary relay can be activated at the
Warning
level or
Alarm
level, depending on programmed function.
(2) The alarm outputs are activated while alarm conditions exist and will stop approximately five seconds after a fire is no
longer detected.
(3) The
Alarm
state can be optionally latched via programmed function. (Default is non-latching).
(4) The detector will remain in
BIT Fault
state until it has passed a successful built-in test.
Note
The outputs depend on the output configurations.
Optional latching
Alarms are set as non-latching by default. However, the detector includes a latched alarm
output capability, which operates according to the programmed function.
If selected, upon detection of a fire, the detection signal is latched until the operator
manually resets the detector (disconnecting the power supply or performing a manual
built-in test [see
Manual built-in test ]).
Latching affects the alarm relay, 0-20 mA output, and the alarm LED. The auxiliary relay is
latched only when the programmable function
Auxiliary Relay is set to Yes.
NOTICE
The auxiliary relay is available only in models with output configurations - 1RXXXXX and
2RXXXXX.
The 0-20 mA is available only in models with output configurations - 1AXXXXX, 2AXXXXX,
and 3AXXXXX.
1.6 Internal detector tests
The detector performs two types of self-tests:
• Continuous feature test
Reference Manual Introduction
00809-0100-4975 August 2019
Rosemount 975MR 21