4 excite, delay, and measure, 5 ac half bridge – Campbell Scientific CR10X Measurement and Control System User Manual
Page 136
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
9-4
TABLE 9-2. Pulse Count Configuration Codes
Code
Configuration
0
High frequency pulse (Index (--) to
change from 8 Hz to 64 Hz reset)
1
Low level AC (Index (--) to
change from 8 Hz to 64 Hz reset)
2
Switch closure
3
High frequency pulse, sixteen
bit counter
4
Low level AC, sixteen bit counter
1X
Long interval data discarded
2X
Long interval data discarded,
frequency (Hz) output
where X is the configuration code
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
01:
2
Repetitions
02:
2
Pulse channel or
Control Port number for
first measurement
03:
2
Configuration code
(Table 9-2)
04:
4
Input location number
for first measurement
05:
FP
Multiplier
06:
FP
Offset
Input locations altered: 1 per repetition
Intermediate storage locations altered: 1 per
repetition
*** 4 EXCITE, DELAY, AND MEASURE ***
FUNCTION
This instruction is used to apply an excitation
voltage, delay a specified time, and then make
a single-ended voltage measurement. The
result is in millivolts when a multiplier of one and
an offset of zero are used. A 1 before the
excitation channel number (1X) causes the
channel to be incremented with each repetition.
The 50 and 60 Hz rejection ranges (Section
13.1) do not have enough time between
integrations to allow a delay.
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
01:
2
Repetitions
02:
2
Range code (Table 9-1)
03:
2
Single-ended channel
number for first
measurement
04:
2
Excitation channel
number
05:
4
Delay in hundredths of
a second
06:
4
Excitation voltage
(millivolts)
07:
4
Input location number
for first measurement
08:
FP
Multiplier
09:
FP
Offset
Input locations altered: 1 per repetition
*** 5 AC HALF BRIDGE ***
FUNCTION
This instruction is used to apply an excitation
voltage to a half bridge (Figure 13.5-1), make a
single-ended voltage measurement of the
bridge output, reverse the excitation voltage,
then repeat the measurement. The difference
between the two measurements is used to
calculate the resulting value which is 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.
The excitation "on time" for each polarity is
exactly the same to insure that ionic sensors do
not polarize with repetitive measurements. The
range should be selected to be a fast
measurement (range 11-15), limiting the
excitation on time to less than 800
microseconds at each polarity. A slow
integration time should not be used with ionic
sensors because of polarization error.
PARAM.
DATA
NUMBER
TYPE
DESCRIPTION
01:
2
Repetitions
02:
2
Range Code (Table 9-1)
03:
2
Single-ended channel
number
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