Measurement Computing StrainBook/616 - Manual (Page 24)

Programmable Features
Channels can be configured through your own custom programs or through the included out-of-the-box
WaveView software. WaveView includes a Channel Configuration screen that allows you to turn channels
on or off, select channel ranges, change channel labels, and select engineering units.
Reference Notes:
o
The WaveView PDF document contains detailed information regarding general
WaveView operations.
o
Chapter 4 of this manual includes WaveView information that pertains to StrainBook
and also to the WBK16 expansion module.
o
In regard to the location of API reference material, including program examples,
individuals who write their own programs should refer to the readme.txt file located on
the install CD-ROM.
Operational Tips
The following tips should help you get the most out of your StrainBook.
(1) Keep things cool.
Operating 120 ohm bridges on 10 volts of excitation is possible with the StrainBook and with the WBK16.
But the strain gages and bridge completion resistors must both be rated for this voltage; otherwise
excessive drift will occur as the gages and resistors heat up. The 120 ohm bridge completion resistors we
offer (part number R-17-120) are of insufficient power rating for 10 volt bridges. If the excitation level is
set to
5 volts, drift is not a problem with our 120 ohm resistors. An alternative is to purchase higher quality,
higher power and higher cost bridge completion resistors (part number S-120-01) from the Measurement
Group.
(2) Understand the difference between calibration and set-up.
Calibration requires measurements of channels with external wiring and gages connected to establish
computational data on which to base gain and offset settings. WaveView’s two-point manual and shunt cal
menu choices provide calibration. Set-up uses manually entered parameters to computationally choose
gain and offset settings. The two-point automatic and nameplate menu choices provide channel set-up.
The nameplate menu selection for strain gages cannot effectively calibrate field configured strain gage
bridges which have not been externally hardware nulled because the software algorithm assumes the zero
point and computes the other settings based on the excitation voltage, gage factor and full scale value
entered by the user. Nameplate “calibration” is intended for packaged and pre-calibrated devices, such as
load cells and pressure transducers with nameplates listing their output sensitivity in mV/V and full-scale
output in engineering units.
(3) Do not attempt to “calibrate” all the channels simultaneously.
Although desirable, it is not possible to globally calibrate all the channels without making any actual
measurements. It is possible to apply global auto-zero to previously calibrated channels that have auto-zero
enabled. However, the original requirement for the channel to have been externally nulled prior to
performing nameplate calibration remains. The overall settings for all of the channels can be stored as a
configuration for re-use; but assuming the overall calibration and external system are unchanged between
chronologically separated tests is risky and not recommended.
2-10 Operation Reference 967794 StrainBook/616