Det-Tronics R8471J Single Channel Gas Controller, OPECL - Manual (Page 15)

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7. Fault leD - Flashes upon detection of a system fault
and is on steady during the power-up time delay.
8. reset Pushbutton - Used for various system
programming and calibration functions as well as
for resetting the controller.
9. Set Pushbutton - Used for various system
programming and calibration functions.
OUTPUTS
The R8471J Controller is available in a Base version and
a Premium version. The differences between the two
models are the output configuration and programming
options.
Base Model - The base controller is furnished with open
collector transistor outputs (rated 100 milliamperes at
32 volts dc) for the Low alarm, High alarm, Auxiliary
alarm, and Fault circuits. The normally de-energized
alarm outputs are energized when their corresponding
setpoints are exceeded. The fault output is normally
energized and becomes de-energized upon detection
of a system fault.
Premium Model - The premium model is furnished
with a set of four relays in place of the four solid
state outputs. The relays have SPST contacts rated 5
amperes at 30 Vdc or 250 vac.
This model also includes a selectable isolated/non-
isolated 4 to 20 mA dc current output for transmitting
system information to other monitoring devices. The
linear 4 to 20 mA output corresponds to levels from
0 to 5 LFL-m. If a system fault is detected, the output
drops to less than 1.0 mA. The current output can be
calibrated in the field to ensure maximum accuracy.
(Refer to the “Calibration” section of this manual for
details.)
AUTOMATIC DIAgNOSTICS AND
FAULT IDENTIFICATION
The microprocessor based controller features self-
testing circuitry that continuously checks for faulty
sensor or open sensor wiring, low or high input voltage,
and other problems that could prevent proper system
response. When power is applied, the microprocessor
automatically tests memory. In the Normal operating
mode, it continuously monitors the input signal from
the OPECL to ensure proper functioning. In addition,
a “watchdog” timer is maintained to ensure that the
program is running correctly. If a fault should occur:
— The Fault LED flashes.
— The digital display identifies the nature of the
fault using an alpha-numeric code. Refer to the
Troubleshooting section for an interpretation of the
codes.
— The normally energized Fault output is
de-energized.
— The dc current output drops to less than 1 mA.
NOTE
The fault code will be shown for about 2 seconds
out of every 5 seconds. The gas concentration at
the sensor will be displayed during the remaining
time. If more than one fault should occur, the
highest priority fault will be displayed.
An alarm condition will normally over-ride a fault
condition unless the fault condition occurred first.
However, faults that affect the actual function of the
controller (F50, F60, F70, F9X) may impair the ability of
the controller to maintain an alarm output.
All faults automatically reset except the F9X faults. After
the fault condition has been corrected, the fault output
automatically switches to the normal (energized) state,
the dc current output returns to normal, and the Fault
LED turns off. Clearing F9X faults requires removing
operating power from the controller for approximately
one second.
CAUTION
The fault detection circuitry does not monitor the
operation of external response equipment or the
external wiring to these devices. It is important
that these devices be checked periodically to
ensure that they are operational.