HP 34970A User Manual page 119

Chapter 4 Features and Functions
Mx+B Scaling
During a Monitor operation, the gain and offset values are applied to
all readings on the specified channel.
You can specify a custom label with up to three characters. You can
use letters (A-Z), numbers (0-9), an underscore ( _ ), or the "#" character
which displays a degree symbol ( ) on the front panel (displayed as a
blank space in an output string from the remote interface). The first
character must be a letter or the "#" character (the "#" character is
allowed only as the leftmost character in the label). The remaining
two characters can be letters, numbers, or an underscore.
Note: If you set the measurement label to C, F, or K, note that this
has no effect on the temperature units set in the Measure menu.
Although the instrument does not directly support strain gage
measurements, you can measure a strain gage using a 4-wire
resistance measurement with scaling. For more information, refer to
"Strain Gage Measurements" on page 373.
Note: HP BenchLink Data Logger software has built-in strain gage
measurement capability.
Use the following equations to calculate the gain and offset.
1
M B
GF x R
0
Where GF is the gage factor and R
For example, a 350 strain gage with a gage factor of 2 would use the
following gain and offset values: M=0.001428571, B= - 0.5 (be sure to
use 6 digits of resolution for this measurement).
1
2
The maximum gain allowed is 1E+15 and the maximum offset
allowed is 1E+15.
The MEASure? and CONFigure commands automatically set the
gain ("M") to 1 and offset ("B") to 0.
A Factory Reset (*RST command) turns off scaling and clears the
scaling values on all channels. An Instrument Preset (SYSTem:PRESet
command) or Card Reset (SYSTem:CPON command) does not clear the
scaling values and does not turn off scaling.
120
1
GF
is the unstrained gage resistance.
0