Emerson Micro Motion 3711, Configuration And Use Manual, Page: 201 / 234

Configuration and Use Manual 193
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Appendix B
Calibration
B.1 About this appendix
The following calibration procedures may be performed as required:
• Analog input calibration, which includes the optional pressure inputs and RTD, and the
auxiliary analog inputs from the Micro Motion sensor – see Section B.2
• Analog output calibration – see Section B.3
• Density calibration – see Section B.4
B.2 Calibrating an analog input or RTD
AI calibration adjusts the span and resolution of the 1–5 VDC or 4–20 mA input to provide a more
accurate representation of the process variable.
During calibration, two to five calibration points are defined: one for the lowest value of the process
variable, one for the higest value of the process variable, and three optional midpoint values.
B.2.1 Preparing for calibration
When preparing for calibration, consider the following:
• The test device should be approximately four times more accurate than the device being
calibrated (the analog input or RTD input on the Model 3711).
• In general, more calibration points provide more accurate calibrations. Midpoint values should
be located around normal operating conditions.
• It may be more appropriate to verify an existing calibration than to perform a new calibration.
If the existing calibration meets requirements, verification avoids disruption of the process,
and also avoids the risk of replacing a good calibration with a poor one. The AI Calibration
panel provides a verification function as well as a calibration function. Calibration verification
is recorded in the event log.
• If the Model 3711 remains idle for an extended period (typically, more than 3600 seconds)
during calibration, it will time out and disconnect. Calibration values are lost, and calibration
must be repeated from the beginning. Be sure that all required equipment and data are
available before beginning calibration.
B.2.2 Calibration procedure
To calibrate an analog input or RTD:
1. Select Configure > I/O > AI Points .
2. Using the Analog Inputs dropdown list, select the AI that you want to calibrate. To calibrate
the RTD, select RTD.