User`s guide

137
Chapter 4 Features and Functions
Mx+B Scaling
4
You can make a null measurement on a channel and store it as the
offset (“B”) for subsequent measurements. This allows you to adjust
for voltage or resistive offsets through your wiring to the point of the
measurement.
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 295.
Note: Agilent BenchLink Data Logger 3 software has built-in strain
gage measurement capability.
Use the following equations to calculate the gain and offset.
M = B =
Where GF is the gage factor and R
0
is the unstrained gage resistance.
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 6½ digits of resolution for this measurement).
1
GF R
0
----------------------
1
GF
--------
34970A Refresh UG.book Page 137 Wednesday, February 17, 2010 12:34 PM