Pressure Systems, Inc. Model 9116 User’s Manual
Page 23
www.PressureSystems.com
3.1.3.1
Interpreting Offset Values (Re-zero Calibration Adjustment)
When a module is instructed to execute the command
Calculate and Set Offsets
(
‘h’
), a datum
corresponding to the calculated
offset correction
term (or coefficient) is returned for each
affected channel. Each such coefficient value is stored internally, and will be subtracted in all
subsequently calculated data conversions, to correct for zero drift effects. The command only
returns them in the response (in current engineering units (EU) of pressure) to allow the user to
make reasonableness checks on them. The
Read Internal Coefficients
(
‘u’
)
command will
return them on demand.
3.1.3.2
Interpreting Gain Values (Span Calibration Adjustment)
When a module is instructed to execute the command
Calculate and Set Gains
(
‘Z’
), a datum
corresponding to the calculated
gain correction
term (or coefficient) is returned for each
affected channel. Like the
offset
coefficient, each
gain
coefficient is stored internally, and will
be used in all subsequently calculated data conversions, to correct for gain change effects. The
command returns them in the response (as a unitless scale factor near 1.0) to allow the user to
make reasonableness checks on them. The
Read Internal Coefficients
(
‘u’
)
command will
return them on demand.
3.1.3.3
Interpreting Engineering Units Output
All modules perform all internal pressure calculations in engineering units of pounds per square
inch (psi). By default, all pressure data in responses and command parameters will also be in
psi. A different engineering unit (e.g., kPa) may be obtained by changing an internal
EU
Pressure Conversion Scaler
(normally 1.0). See the “
Read/Download Internal Coefficients
”
(‘u’/‘v’)
commands (array 11, coefficient 01).
Change this default multiplier value (1.0) to obtain
units other than psi.
3.1.4
Functional Command Overview
The various
commands for
Model 9116
modules are best introduced by classifying them into
functional groups and then describing how each function is carried out in a typical system. The
following functions are defined for this purpose:
•
Start-up Initialization
•
Scan List Definition for Acquisition
•
Calibration Adjustment of Engineering Unit
Correction
Coefficients
•
Acquisition/Delivery of Data to Host
•
Network Query and Control
Please look ahead to
Table 3.1
, labeled
Model 9116 Intelligent Pressure Scanner
Commands
, in
Section 3.2
, for a quick-look summary of all commands available to the
Model
9116
modules. Each command may be referenced by both its
functional title
and by its
command id
in the functional discussion sub-sections below.
The
Detailed Command Description
Reference
immediately follows the table in
Section 3.2
,
with each command description occupying a page (or more if necessary). Command
descriptions in this section (as in the table) are ordered first by
type
(TCP/IP then UDP/IP), then
by
“command id”
in
ASCII order
(
UPPERCASE
letters (
A .. Z
) first, then
lowercase
letters (
a ..
z
)) .
