Measurement Specialties 9116 - Manual (Page 32)

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)) .