Measurement Specialties 9116 Functional Command Overview, Interpreting Engineering Units Output

Pressure Systems, Inc. Model 9116 User’s Manual

3.1.3.1Interpreting 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.

3.1.3.2Interpreting 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.

3.1.3.3Interpreting 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.

3.1.4Functional 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)) .

Page 23 www.PressureSystems.com