Active Transducer
The active transducer is identified by the display
along with any pressure readings. If there is no
identity showing then the pressure is from the
primary transducer. Otherwise, the display will
show the transducer address on the bottom line,
i.e., press [2nd] [9]:
CONTROL PRESS: (NORM) nn.nnn PSI A
MEASURED @ 01:
nn.nnn PSI A
[S]
This display shows that the instrument is in CON-
TROL mode, at a specified value (nn.nn PSI A), and
that the pressure is being measured by the secon-
dary transducer assigned address 1 (@ 01), and
that the pressure is stable [S]. To select a different
transducer to be the active transducer, or to select
AUTORANGE
,
key in
[2nd] [3] [=] [+] [+]...
until the transducer to be activated appears in the
display. When the correct transducer is showing
press [=] to execute the command to SET ACTIVE
TRANSDUCER.
MEASURE MODE
Remember, the primary transducer is the highest
range internal transducer. Do not apply any pres-
sure to the MEASURE/CONTROL port that exceeds
this transducer’s overrange capacity.
In MEASURE mode the system will recognize the
last active transducer used in CONTROL mode. If,
for example, the unit was in CONTROL using the
lower pressure (secondary) transducer, that
transducer will remain active when switched to
MEASURE. If the pressure applied through the
MEASURE/CONTROL port exceeds the limit for
the secondary transducer the protective relief valve
will open. The recommended practice for multiple
internal transducers is to always determine the
current active transducer prior to switching to
ME ASUR E m ode, a nd th en chan ge active
transducers when necessary, or run
AUTORANGE
which lets the system select the most suitable
transducer. (
AUTORANGE
is explained below).
A potential hazard is that pressures in excess of the
secondary transducer limit can be trapped inside
the pneumatic system if the instrument was last
used in CONTROL mode. If a lower range
transducer is then selected and placed in MEAS-
URE mode, that high pressure will appear momen-
tarily at the lower transducer’s sensing element. As
a matter of practice, DO NOT activate a lower
pressure (secondary) transducer until the internal
pressure has dropped to a level at or below its full
scale range.
These cautions do not apply to the optional baro-
metric reference transducer. If one is present, it is
internally isolated from the rest of the pneumatic
system, and can be made active, and placed in
MEASURE mode at any time with complete safety.
Now, with all of that said, to measure pressure
press keys [2nd] [8]:
MEASURE MODE:
MEASURED @ 01:
nn.nnnn PSI A
Pressing [=] is not required. The unit immediately
displays three items of information: 1, the mode
(top line); 2, the active transducer (MEASURED:
blank if the primary transducer is selected, or
@
nn: for a selected secondary transducer); and 3, the
pressure applied to that transducer’s pressure port
(nn.nnnn PSI A).
If the measured pressure is at or below another
transducer’s FS range, then that transducer should
be activated in order to get the most accurate
pressure readings. Generally, using the lowest
available range transducer that is still above the
pressure to be measured will provide the greatest
resolution and best accuracy.
Autorange
The AUTORANGE feature is now standard for units
with multiple internal transducers. It functions
similar to the feature provided on many digital
multimeters. With AUTORANGE enabled the in-
strument selects the internal transducer that will
provide the highest resolution for the pressure
being sensed. When selected it is operational in any
of the four function modes: STANDBY, MEASURE,
CONTROL or VENT, but it is limited to internal
transducers, only. In AUTORANGE the system will
automatically switch between transducers at the
following crossover points:
Upscale:
If there is a higher range transducer than
the active transducer the switch will occur at 5%
over FS for the active transducer.
Downscale:
If there is a lower range transducer
than the active transducer the switch will occur at
2.5% above FS for the lower range transducer.
With AUTORANGE off (normal range-hold opera-
tion) all pressure functions are directed to the
currently active transducer. That transducer will
LOCAL OPERATION
PCS 400
3-8
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Summary of Contents for PCS 400
Page 13: ...User s Notes TABLE OF CONTENTS PCS 400 xii www mensor com ...
Page 23: ...User s Notes INSTALLATION PCS 400 2 4 www mensor com ...
Page 41: ...User s Notes LOCAL OPERATION PCS 400 3 18 www mensor com ...
Page 73: ...User s Notes SPECIFICATIONS PCS 400 7 4 www mensor com ...
Page 115: ...User s Notes INDEX PCS 400 10 6 www mensor com ...
Page 116: ......
