Measurement Specialties 9116 - Manual (Page 104)

Pressure Systems, Inc. Model 9116 User’s Manual
Page 95 www.PressureSystems.com
For Model 9116, with integral DH200 transducers, internal manifolds and valves allow a Span
adjustment pneumatic calibration to be accomplished easily and automatically.
It is recommended that a Span adjustment be performed whenever new transducers are
installed in the instrument. In such cases, the new gain coefficients that result should always be
stored back into the transducer’s non-volatile memory. In other cases, the user’s application
may not require periodic span adjustment since 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 Calculate and Set Gains (‘Z’) command, the module will perform
the Span adjustment calibration, and then update the gain coefficients in its memory. It will
subsequently use the newly calculated gain terms for subsequent engineering-unit calculations
until power is lost to the module.
Note
When using the Calculate and Set Gain (‘Z’) command, only the local
variables in the module’s volatile main memory (RAM) are changed.
4.3.1. Span Calibration Valve Control
Before executing a Span adjustment (Calculate and Set Gains (‘Z’) command), the Model
9116 modules should have their calibration manifold valve placed in the proper position. For
single pressure range units the CAL position should be used since the span calibration pressure
can be applied between the CAL and CAL REF ports. Since the module will not attempt to shift
this valve automatically, as it does for Re-zero adjustment, it should manually be placed in the
desired position with the Set Operating Options (‘w’) command (option indexes = 0C and 12).
When span 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. Refer to Calculate and Set Gains (‘Z’) command to specify the
channels to be affected by the command in a multi-range unit. 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 command (‘Z’) has a channel selection bit map parameter allowing it to
calibrate only the desired pressure channels, the RUN port is a viable option for supplying the
calibration pressures.