Pressure Systems 9022 - Manual (Page 123)

Pressure Systems, Inc. NetScanner™ System (9016, 9021, & 9022) User’s Manual
www.PressureSystems.com 4 - 13
NOTE: When using the 9021/9022 with digitally compensated PSI Model 9400
transducers, the span calibration functions (for the 9400 transducers) can
serve as a method to correct both 9400 and internal 9021/9022
measurement accuracies. Periodic use of this span calibration function
can eliminate the need for the described voltage reference calibration
when using the 9021/9022 with digitally compensated Model 9400
transducers.
Place calibration manifold back into the RUN position, if
the CAL position was used. [w0C00] **
Store new offset and gain coefficients into transducer
non-volatile memory. w08
w09
… continue normal data acquisition.
4.5 9021/9022 Analog Calibration
Both the standard 9021 and the 9022 modules are used to make absolute analog measurements from
either the PSI 9400 transducers or third party analog output transducers. In order to maintain the
highest level of analog accuracy, the 9021/9022 is designed to allow its firmware to perform
automatic software calibration of the analog interface circuitry. This automatic, firmware controlled
calibration function minimizes analog offset and gain errors for each of the twelve 9021/9022 input
channels. This auto-calibration function reduces analog measurement errors resulting from long
term or thermally induced component drift. Unless disabled through software commands to the
9021/9022, this software calibration function will be constantly performed by the 9021/9022
firmware, therefore maintaining consistent measurement accuracy within the 9021/9022. In
order to perform this software calibration function, the 9021/9022 contains one internal voltage
reference network. This internal calibration standard is designed to provide excellent long term and
thermal stability. This use of a common reference network reduces user or factory calibration of
the 9021/9022 to a simple calibration of this one internal reference network. The following
procedures describe the methods for verifying analog measurement accuracy and for calibrating this
internal reference in order to maintain optimum accuracy through the 9021/9022.