I2773-4.4 en
65
Somat eDAQ
lite
These options define the slope of the calibration line. Enter the engineering units
equivalent for the span. The eDAQ
lite
internally applies the selected shunt resistor
across one arm of the bridge and measures the preshunt and postshunt signal
voltages.
Notes on Shunt Span Modes
•
The eDAQ
lite
stores the precise values for each of the shunt resistors in nonvolatile memory on the hardware layer.
The eDAQ
lite
performs the necessary computations to compensate for each shunt resistor's deviation from the exact
values presented in the above list.
•
For ELBRG or Strain SMART Module channels, use the Install Shunts and Remove Shunts options in the Shunt Control
sub-menu of the Test Control menu to install or remove the shunt calibration resistors during a test run or preview. Use
the test run data to quickly verify that all applicable channels are nominally calibrated. While this data can also be used
to verify calibration accuracy in a strict sense, this is a more complicated process that requires knowledge of actual
excitation voltage and actual shunt resistor value. The test can be stopped with the resistors still installed, as th
e
eDAQ
lite
always removes shunt resistors when preparing for a new run, a channel display or any calibration task. For
networked eDAQ
lite
/eDAQ systems, the shunt resistors are installed or removed sequentially from one network node
to the next.
NOTE
Although this task requires a fairly small amount of eDAQ
lite
processing, it can result
in a DeviceOverFlow error reset for tests running at the edge of the eDAQ
lite
processing limit.
•
An internal shunt resistor applied across the +Ex to -Sig leg of the bridge results in a downscale shunt. In other words,
the voltage output from the bridge swings in the negative direction when the shunt is applied. Take this into
consideration when setting the sign of the associated engineering value.
•
If the measured voltage span and the theoretical ideal voltage span do not agree within the specified percentage found
in the TCE General Preferences, TCE issues a warning message.
Preshunt Value
Specify a preshunt value to define a single point on the calibration line in conjunction
with one of the shunt span modes (e.g., 40-kilohm span). Enter the engineering units
equivalent. The voltage used is the preshunted voltage measured in the shunt span
step. This mode is recommended to reduce the entire calibration to one step.
Shunt Tools
For a bridge channel, use the shunt tools option as a guide to indirectly select a shunt
span mode (e.g., 40-kilohm span) with an associated engineering equivalent value.
The two options for shunt calibration are based on a known shunt calibration or gage
and bridge factors.
Channel Additional Modes
ELBRG 50-kilohm span, 100-kilohm span, 200-kilohm span,
500-kilohm span
Strain SMART
Module
50-kilohm span, 100-kilohm span
HBM: public
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