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.
