Pressure Systems, Inc. Model 9116 User’s Manual
Page 98
www.PressureSystems.com
4.4
Integrated Multi-Point Calibration Adjustment
Model 9116
Intelligent Pressure Scanners may have their accuracy enhanced by regular
application of one or both of the individual
Re-zero
and
Span
calibration adjustment functions
already described in
Sections 4.2
and
4.3
. An integrated and more comprehensive
Multi-Point
Calibration
function may be used instead to adjust the same
offset
and
gain
coefficients for a
module’s channels. This function also provides for supplying additional calibration points, which
is particularly useful when it is desired to fit the adjustment data to the entire negative and
positive range of the module. This integrated calibration adjustment function is fully described in
this section. It is implemented by four (4) sub-commands of the
‘C’
command. Since this
function combines the functions of the Re-zero and Span calibration adjustments (using the
‘h’
and
‘Z’
commands) it is recommended that you read the information of
Section 4.2
and
4.3
before attempting to perform this multi-point calibration.
It is recommended that a
Multi-Point Calibration
adjustment
be performed whenever new
transducers are installed in your module. In such cases, the new
zero
and
gain
coefficients that
result should always be restored into the transducer’s non-volatile memory afterwards. In some
cases, the user’s application may not require such a comprehensive adjustment as the other
factory-determined pressure/temperature coefficients (stored permanently inside each
transducer) are extremely stable. Only an occasional
Re-zero adjustment
may be all that is
necessary.
When instructed to execute a particular sequence of sub-commands of the
Configure Multi-
Point Calibration
(
‘C’
) command, the module will perform the various stages of the
Multi-Point
Calibration adjustment
calibration function, and then update both the
offset and gain coefficients
in the module’s volatile (e.g., RAM) memory. The module will use this newly calculated data
term for all subsequent engineering-unit calculations.
4.4.1.
Multi-Point Calibration Valve Control
Before executing a
Multi-Point Calibration
adjustment (using various forms of the
Configure/Control Multi-Point Calibration
(
‘C’
) command),
Model 9116
modules should have
their calibration valve placed in the proper position. For modules with only one common
pressure range for its transducers, the
CAL
position should be used since the span calibration
pressure can be applied between the
CAL
and
CAL REF
ports (see
Section 4.3.1
for more
information on these ports). Since the module will not attempt to shift this valve automatically,
as it does for Re-zero adjustment, it should be placed in the desired position
manually
with the
Set Operating Options
(
‘w’
) command (option indexes = 0C and 12). This is illustrated in the
example of the next section.
Note
When using the
Configure/Control Multi-Point Calibration
(‘C’)
command, only the local variables in the module’s volatile main
memory (RAM) are changed.
When multi-point calibrating
Model 9116
modules with
multiple ranges
installed, the
CAL
port
may be used to apply pressure to all transducers
only if the specified proof pressure is not
exceeded on any channel.
If the application of a specific span pressure exceeds the proof
pressure rating of any other transducer contained within the same scanner, the calibration
pressures must be applied to the
RUN
side pneumatic input ports. Since the calibration
