Campbell Scientific CR7 Measurement and Control System User Manual
Page 93
SECTION 9. INPUT/OUTPUT INSTRUCTIONS
9-3
TABLE 9-2. Pulse Count Configuration
Codes
Code
Configuration
00
High frequency pulse, all pulses
counted
01
Low level AC, all pulses counted
02
Switch closure, all pulses counted
1X
Long interval data discarded, where X
is configuration code
2X
Long interval data discarded, frequency
(Hz) output
PAR.
DATA
NO.
TYPE
DESCRIPTION
01:
2
Repetitions
02:
2
Card number for first
measurement
03:
2
Pulse channel number for
first measurement
04:
2
Configuration code (Table 9-2)
05:
4
Input location number for first
measurement
06:
FP
Multiplier
07:
FP
Offset
Input 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.
PAR.
DATA
NO.
TYPE
DESCRIPTION
01:
2
Repetitions
02:
2
Range code (Table 9-1)
03:
2
Analog card number for first
measurement
04:
2
Single-ended channel
number for first
measurement
05:
2
Excitation card for first
measurement
06:
2
Excitation channel number
for first measurement
07:
2
Number of measurements
per excitation channel
08:
4
Delay (0.01 sec)
09:
FP
Excitation voltage (millivolts)
10:
4
Input location number for first
measurement
11:
FP
Multiplier
12:
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.
When the 1500 or 5000 µV input range is
selected, the value is returned as 1000 times
the ratio. For all other input ranges the value is
just the ratio.
The excitation "on time" for each polarity is
exactly the same to ensure that ionic sensors do
not polarize with repetitive measurements. The
range should be selected to be a fast
measurement (range 11-18) limiting the excitation
on time to 800 microseconds at each polarity. A
slow integration time should not be used with
ionic sensors because of polarization error.
PAR.
DATA
NO.
TYPE
DESCRIPTION
01:
2
Repetitions
02:
2
Range code (Table 9-1)
03:
2
Analog card number for first
measurement
04:
2
Single-ended channel
number for first
measurement
05:
2
Excitation card for first
measurement
06:
2
Excitation channel number
for first measurement
07:
2
Number of measurements
per excitation channel
08:
4
Excitation voltage (millivolts)
09:
4
Input location number for first
measurement
10:
FP
Multiplier
11:
FP
Offset
Input locations altered: 1 per repetition