Measurement Specialties 9116 - Manual (Page 107)

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