Acqiris SA240P - How to Calibrate the Card

7.2 How to calibrate the card?
Acqiris SA240P User's Manual 71
7.2 How to calibrate the card?
Calibration principle
The card is initialized without calibration.
A calibration is mandatory before making any acquisition to guarantee measurement accuracy. The
MD3 driver prevents an acquisition from being performed unless a self-calibration has first been
completed.
Since a full internal calibration of an ADC card can be time consuming because of the many possible
configuration states, the self-calibration is performed only for the current configuration state. A new
self-calibration is required after every change of configuration of the card.
See Calibration (page 13) section.
Running fast calibration
The function SelfCalibrate should be used to perform a fast calibration.
As explained above, a calibration is required after every acquisition parameter modification (e. g.
full scale range, filter, sample rate, ...). The IAqMD3Calibration.IsRequired
IVI.NETproperty or the AQMD3_ATTR_CALIBRATION_IS_REQUIRED IVI-C attribute can be
used to check if a new self calibration is required .
MD3 Smart-calibration
The smart calibration implemented in MD3 drivers allows to save time by automatically keeping in
memory the calibration information from any self-calibration performed since the beginning of the
session. When the acquisition parameters are changed, no re-calibration of the card is necessary if
a self-calibration has already been performed with the same acquisition conditions (i.e. the same set
of parameters), unless the clock mode parameters are changed.
Indeed, any change in the clock mode parameters (i.e. External clock frequency or Reference
mode parameters), induces a restart of the clocks which requires a new self-calibration.
Calibration optimized for a target voltage
It is possible to optimize the calibration for a specified target voltage. In this case, the self-calibration
will minimize the noise level at the channel input value equal to this specified target voltage.
When setting to true the Calibration.TargetVoltageEnabled property , the self-calibration
will minimize the noise level at the channel input value equal to
Channel.CalibrationTargetVoltage. Note that when set to true, the Channel.Offset
value is taken into account in the self-calibration, and therefore changing the
Channel.CalibrationTargetVoltage value, or changing the Channel.Offset, will require
a new self-calibration.