Campbell Scientific CR510 Basic Datalogger - Manual (Page 157)

SECTION 13. CR510 MEASUREMENTS
13-13
integration as is normally the case (Section
13.2). The result stored is the voltage
measured. Instruction 8 does not have as good
resolution or common mode rejection as the
ratiometric bridge measurement instructions. It
does provide a very rapid means of making
bridge measurements as well as supplying
excitation to circuitry requiring differential
measurements. This instruction does not
reverse excitation. A 1 before the excitation channel number (1X) causes the channel to be
incremented with each repetition.
The output of Instruction 8 is simply the voltage
measurement. When 8 is used to measure a
full bridge (same connections as Instruction 6 in
Figure 13.5-1), the result is V
1
which equals V
x
(R
3
/(R
3
+R
4
) - R
2
/(R
1
+R
2
)). (In other words, to
make the output the same as Instruction 6, use
a factor of 1000/V
x
in the multiplier.)
FIGURE 13.4-1. Circuits Used with Instructions 4-9