Measurement Specialties 9116 user manual Integrated Multi-Point Calibration Adjustment

Pressure Systems, Inc. Model 9116 User’s Manual

4.4Integrated 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-zeroand 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

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