Measurement Computing WaveBook rev.5.3 - Manual (Page 118)

7-10 Troubleshooting 979194 WaveBook User’s Manual - IO version
13. WBK16 channels won’t calibrate.
Possible Causes Details and Possible Solutions
Resistors are
positioned wrong
and/or poorly
soldered.
If the bridge completion resistors (BCRs) and/or shunt calibration resistors were improperly positioned
or poorly soldered, the WBK16 will not calibrate properly. Check the BCR and shunt arrangements for
the applicable bridge configuration. Also verify that the BCRs and shunt resistors are properly
soldered. Test the solder joints by measuring the resistors through the header pins, which they are
soldered to. If they don’t measure within the allowed tolerance the associated resistors should be
unsoldered, the old solder removed, and then the resistors should be properly re-soldered.
The WBK16’s hardware setup section, in the WBK Options Manual, includes illustrations of various
bridge configurations. A PDF version of the document is included on the data acquisition CD.
Calibration
parameters are
invalid.
If invalid calibration parameters are entered into the WBK16’s calibration program, the channels will
not calibrate correctly. See note.
If using shunt cal, make sure that the resistor values used are actually simulating the expected amount
of bridge deflection.
Verify that units are used consistently in all pertinent entry fields. For example, if you enter the
maximum applied load as units of micro-strain, then enter the shunt units in units of micro-strain too.
For additional information see the “Using the Sensor Calibration Program” section of the WBK
Options Users Manual and the Wave Cal section of the WaveView and WaveCal document. PDF
versions of the documents are included on the data acquisition CD.
Note: WaveView’s System pull-down file includes an “Options” selection. If selected, a dialog box
will appear with a Calibration panel. This panel contains 2 radio buttons. The first selects the
Factory Calibration Table, the second selects a User Calibration Table.
Factory Calibration Table (default), the software uses the factory generated calibration constants
of each system component to achieve calibration of the system. This is useful if the system
calibration changes often.
User Calibration Table, the WaveCal program lets you perform a calibration of the complete
signal path from input to A/D stage. The cal constants are stored in the Calibration Table on the
WaveBook main board. Recalibration is required when any part of the signal path changes.
This method is useful when the configuration remains stable and you want slightly better
accuracy.
Active Bridge
Elements, or
Load Cell are
not adequately
powered.
Ensure that bridge circuits [including load cells] are adequately powered. Refer to theWBK16 section
of the WBK Options Manual for additional information.