Det-Tronics OPECL Infrared Hydrocarbon Gas Detector - Manual (Page 7)

5 95-8556 10.1
faUlT INDICaTION
Faults and status conditions are indicated using the 4-20
mA analog signal output. Refer to Table 3. Signaling
modes include two predefined and one user defined
mode. OPGD-Rx mode (default) is available as well as
a user defined mode for third party compatibility.
TRaNSmITTER lamp OpERaTION
Dual xenon lamps illuminate the linear detection path
from the transmitter to the receiver. Should excessive
degradation of the light intensity occur, the transmitter
automatically increases the light output of the bulbs.
The receiver recognizes this condition by the change
in flash pulse coding and responds by initiating a "Tx
Lamp Fault" warning signal. Total system operation
is maintained, with no loss of sensitivity or detection
performance.
In this mode of operation, the following occur:
1. The indicator LED turns yellow on both the
transmitter and the receiver.
2. HART and MODBUS communication warn of a “Tx
Lamp Fault” condition.
3. The 4-20 mA signal drops from a normal 4 mA to 3.0
mA in OPGD-Rx mode (default) or 2.4 mA in PIR9400
mode. The analog output value is overridden if the
gas level exceeds 0.5 LFL-meters. All gas alarm
signals will occur as normal.
4. The EQP system indicates a trouble condition.
Service should be arranged as soon as possible. A new
transmitter module should be installed.
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The “Tx Lamp Fault” condition indicated by the
4‑20 mA output can be acknowledged by applying
a magnet to the transmitter module for at least
5 seconds. The coded flash sequence will then
return to normal, which causes the 4‑20 mA signal
at the receiver module to also return to normal.
The indicator LeD on the receiver will return to
green, however, the indicator LeD on the transmitter
will remain yellow to annunciate the lamp fault
condition. This condition will continue until power
to the transmitter unit is cycled or the lamps no
longer operate.
Table 3—Detector Status Conditions Indicated by Current Level
*Device is still functional. Gas overrides this indication.
Status 4-20 ma level (±0.1)
OpgD-Rx pIR9400
(Default)
Normal Gas: –0.35 to 5 LFL-M 2.88 to 20.0 2.88 to 20.0
Warmup
1.0 1.0
Zero Calibration 1.0 2.2
Calibration Fault 1.0 1.6
Beam Block 2.0 1.0
Tx Lamp Fault* 3.0 2.4
Calibrate Active at Startup 1.0 0.6
EE Error 1.0 1.2
Ref. ADC Saturated 1.0 0.2
Active ADC Saturated 1.0 0.4
24 VDC Fault 1.0 0.8
Zero Drift 1.0 2.4
Flash CRC Error 1.0 1.2
RAM Error 1.0 1.2
Over Range 20.4 20.4