2-Point Pressure Calibration (Defined); 2-Point Pressure Calibration (Gauge Transducers); 2-Point Pressure Calibration (Procedure) - Honeywell ERX User Manual

2-Point Pressure Calibration (Defined)

A 2-Point Pressure Calibration requires that two different pressures be applied to the instrument's
pressure transducer and be sampled by the data acquisition circuits. A low pressure value,
usually 0.00 PSI, is applied to determine the Pressure Zero Calibration (offset). A higher pressure
value is applied to determine the Pressure Span Calibration (gain). The default Calibration
Parameters require that the Span Pressure exceeds the Zero Pressure by at least 50% of the
transducer range, otherwise a "Points Too Close" error message is displayed.
To produce a linear pressure response for all rated pressures and temperatures, each transducer
has been factory characterized for ambient temperature effects. The characterization process
determines the proper compensation coefficients for each transducer. The 2-point calibration
process uses the coefficients when calculating the pressure offset and pressure span values. Once
these two points have been calculated and stored in the instrument's memory, all other applied
pressures and temperature are automatically compensated by the coefficients.

2-Point Pressure Calibration (Gauge Transducers)

2-point pressure calibration (items required)
• ERX Recorder
• Pressure source and fittings (capable of providing pressures of at least 50% of the ERX
pressure transducer range)
• Pressure Reference (accuracy to equal or exceed the accuracy of the ERX pressure
system)
• Computer (IBM Compatible)
• MasterLink32 Software
• I/O cable, part number 40-1629 and a MPA, part number 40-2620 or through the use
of I/O cable, part number 40-1629 only if the instrument is equipped with an external
case connector and a third option is through the use of I/O cable 40-2696 that connects
directly to J5 on the main circuit board.

2-point pressure calibration (procedure)

Make certain that the Pressure Compensation Coefficients listed are for the pressure transducer
installed. Also verify that Item Code 087 is the desired pressure unit. Item Code 138 matches the
transducer serial number label and item 112 is set for Gauge type transducer. Since the two-point
calibration is mostly a software function, references to the appropriate sections in the
MasterLink32 Link software are included.
1. Connect the pressure source and pressure reference to the ERX pressure connector.
2. Make a serial connect from the computer's serial port to the ERX serial port.
3. Start MasterLink32 software on the computer.
4. Enter the access code for Level 1 or Level 2 when requested. The default Level 1 Access
Code is "11111", the default Level 2 Access Code is "22222".
5. If a communications link has not yet been established, the screen will display a box
requesting the user to input the Instrument Access Code. Enter the access code when this
box appears. The default code is "33333"
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