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95-8676
3.1
OPERATION
FACTORY DEFAULT SETTINGS
The PointWatch Eclipse CO
2
model is shipped from
the factory pre-calibrated and set for carbon dioxide at
0-2%/vol (0-20000 ppm).
OPERATING MODES
The Eclipse has three operating modes: warm-up,
normal, and calibrate.
Warm-up
Warm-up mode is entered upon application of 24 Vdc
operating power. During warm-up, the 4-20 mA current
loop output will indicate warm-up, the indicating LED is
yellow, and the alarm outputs are disabled. The warm-
up mode lasts nominally two (2) minutes after power-up.
Normal
After warm-up mode is completed, the device
automatically enters the Normal mode, and all analog
and alarm outputs are enabled.
Calibrate
Calibration of the Eclipse is normally not required;
however, the user has the option to verify proper
calibration or to perform calibration procedures if
necessary. Guidelines for when to perform a calibration
or a response test are listed in Table 2. The user has
the choice of three methods to place the device into the
Calibrate mode. Refer to the "Calibration" section in this
manual for details.
4-20 mA CURRENT LOOP OUTPUT
Eclipse provides an isolated, linear current loop output
that is proportional to the detected gas level. Fault and
calibration status are also indicated by this output.
The factory setting for full-scale 2%/vol output is 20 mA.
HART and MODBUS interfaces also have the ability to
calibrate the 4 mA and 20 mA levels.
When the default setting is selected, the CO
2
% Volume
for a given current reading can be calculated using the
formula:
% CO
2
= (X – 4) x 0.125
X = Current reading
in milliamperes
Example: Device reads 12 mA.
% CO
2
= (12 – 4) x 0.125 = 1%/vol
Normally, the current loop output is proportional to the
selected standard gas type only.
Table 2—Calibration or Response Test
Function
Calibration
Response
Test
Startup
X
Replace any part
X
Constant zero offset
X
Periodic Functional Testing
(at least once a year)
X
