Section 9. Input/Output Instructions
9-7
Instruction 6: Full Bridge with Single Differential Measurement
This instruction is used to apply an excitation voltage to a full bridge (see Section
13) and make a differential voltage measurement of the bridge output. The
measurement is made with the polarity of the excitation voltage both positive and
negative. The result is 1000 times the ratio of the measurement to the excitation
voltage. A 1 before the excitation channel number (i.e. 1x, where x is the initial
excitation channel number) causes the channel to be incremented with each
repetition.
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
01:
2
Repetitions
02:
2
Range code (Table 9-1)
03:
2
Differential input channel number for first measurement
04:
2
Excitation channel number
05:
4
Excitation voltage (millivolts)
06:
4
Input location number for first measurement
07:
FP
Multiplier
08:
FP
Offset
Input locations altered: 1 per repetition
Instruction 7: Three-Wire Half Bridge with Single Differential
Measurement
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 for
lead wire resistance.
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 the sensor) 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 (i.e. 1x, where x is the initial excitation channel number) causes
the channel to be incremented with each repetition.
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
01:
2
Repetitions
02:
2
Range code for both measurements (Table 9-1)
03:
2
Single-ended input channel number for first
measurement
04:
2
Excitation channel
05:
4
Excitation voltage (millivolts)
06:
4
Input location number for first measurement
07:
FP
Multiplier
08:
FP
Offset
Input locations altered:
1 per repetition