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

2-Point Pressure Calibration (Defined)

A 2-Point pressure calibration requires two different pressures be applied to the instrument's pressure
transducer and be sampled by the data acquisition circuits. A low pressure value, usually 0.0 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 exceed 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 are automatically
linearized and temperature compensated by the coefficients.

2-Point Pressure Calibration Procedure (Gauge Transducers)

2-Point Pressure Calibration (Items Required)
- Mini-AT
- Pressure Source and fittings (capable of providing pressures of at least 50% of the Mini's pressure
transducer range)
- Pressure Reference (accuracy to equal or exceed the accuracy of the Mini-AT's pressure system)
- Computer (IBM Compatible)
- Mini-AT Link Software (or MasterLink32)
- I/O cable, p/n 40-1629

2-Point Pressure Calibration (Procedure)

Make certain that the Pressure Compensation Coefficient listed in item codes 301 through 332 (341 through
372 for PLog) are for the pressure transducer installed. Also verify that Item Code 087 (or 408) is the desired
pressure unit. Item Code 138 (or 411) matched the transducer serial number label and Item Code 112 (or 407)
is set for Gauge type transducer. Refer to figure 19 when pressure calibrating the Mini-AT. Since the two-
point calibration is mostly a software function, references to the appropriate sections in the Mini-AT Link (and
MasterLink32) software are included.
1) Connect the pressure source and pressure reference to the selected Mini-AT pressure connector.
(PCor or Plog)
2) Using serial cable p/n 40-1629, connect from the computer's serial port to the Mini-AT's RS-232
port.
3) Start Mini-AT Link software (or MasterLink32) 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. It is strongly recommended to change the
access code at the time of installation and there after change periodically (requires Level2
Access).
5) Select "Calibrate" from the main menu.
6) Select "PCor Pressure Calibration" or "PLog Pressure Calibration" from the sub-menu. Note: In
MasterLink32 first select "Pressure" then a box will appear for selecting PCor or PLog.
7) If a communications link has not yet been established, the software will attempt to link to the
Mini-AT. If the access code of the Mini-AT is not the default of '33333', a box will appear
requesting the user to input the Instrument Access Code. Enter the access code when this box
appears.
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