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2
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FP
FP
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SECTION
9.
INPUT/OUTPUT INSTRUCTIONS
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
Repetitions
Range code
Input
channel number for
first measurement
Excitation channel
number
Excitation voltage
(millivolts)
Input location number
for
first measurement
Multiplier
Offset
Input locations
altered:
1
per measurement
***
6
FULL
BRIDGE
***
FUNCTION
This instruction is used to apply an excitation
voltage
to
a
full bridge (Figure 13.5-1), make a
differential
voltage measurement
of
the bridge
output, reverse the excitation voltage, then
repeat
the measurement. The result is 1000
times
the ratio of the measurement to the
excitation
voltage. A
1
before the excitation
channel number (1X) causes the channel
to
be
incremented with
each repetition.
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
Repetitions
Range code
Input
channel number for
first measurement
Excitation channel
number
Excitation voltage
(millivolts)
Input location number
for
first measurement
Multiplier
Offset
Input locations
altered:
1
per measurement
***
7
THREE
WIRE HALF
BRIDGE
***
FUNCTION
This instruction is used to determine the ratio of
the
sensor resistance to a known resistance
using a separate voltage sensing wire from
the
sensor to compensate
tor lead wire resistance.
9-4
The measurement sequence
is
to apply an
excitation
voltage,
make two voltage
measurements on two adjacent single-ended
channels, the
first
on
the reference resistor and
the second
on
the voltage sensing wire from
sensor (Figure 13.5-1),
then reverse the
excitation voltage and repeat the
measurements. The two measurements are
used to calculate
the resulting value, which
is
the ratio
of
the voltage across the sensor to the
voltage across
the reference resistor.
A
1
before
the excitation channel number
(1X)
causes the
channelto
be incremented with
repetition.
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
2
Repetitions
2
Range code for both
measurements
Input
channel number for
first measurement
2
Excitation channel
4
Excitation voltage
(millivolts)
Input location number
for
first measurement
FP
Multiplier
FP
Otfset
Input locations
altered:
1
per measurement
***
8
DIFFERENTIAL VOLTAGE
WITH
***
EXCITATION
AND DELAY
FUNCTION
This measurement consists of applying a single
excitation voltage, delaying a specified time,
making
a
differential
voltage measurement. lf
a
0 delay is specified,
the inputs are not switched
for a second integration
as is normally the case
with
a
differential measurement (Section
13.2).
The result stored
is
the voltage measured.
W
a
delay of
0 lnstruction 8 does not have as
resolution or
common mode rejection as the
ratiometric
bridge measurement instructions. lt
does provide
a
very rapid means of making
bridge measurements as well as supplying
excitation to
ci
rcu
itry
requ
i
ri n
g
d iff
erential
measurements. This instruction does not
reverse excitation.
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FP
FP
07:
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