Campbell CR7 Bedienerhandbuch PDF herunterladen (Seite 95)

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

9-5

PAR. DATA

NO. TYPE DESCRIPTION

01: 2 Repetitions (47 max)

02: 2 Excitation range code (Table

9-1)

03: 2 Bridge range code for (Table

9-1)

04: 2 Analog card number for first

measurement

05: 2 Differential channel number

for first measurement

06: 2 Excitation card for first

measurement

07: 2 Excitation channel number

for first measurement

08: 2 Number of measurements

per excitation channel

09: 4 Excitation voltage (millivolts)

10: 4 Input location number for first

measurement

11: FP Multiplier

12: FP Offset

Input locations altered: 1 per repetition

*** 10 BATTERY VOLTAGE ***

FUNCTION

This instruction reads the battery voltage from

the currently active I/O module and writes it to

an input location. The units for battery voltage

are volts.

PAR. DATA

NO. TYPE DESCRIPTION

01: 4 Input location number

Input locations altered: 1

*** 11 107 THERMISTOR PROBE ***

FUNCTION

This instruction applies a 4 VAC excitation

voltage to Campbell Scientific's Model 107

Thermistor Probe, makes a fast, single ended

voltage measurement on the 15 mV range

across a resistor in series with the thermistor

and calculates the temperature in

o

C with a

polynomial. The maximum polynomial error

from -40

o

C to +55

o

C is given below:

Curve Fit Error --

Range (

o

C) Error (

o

C)

-40 to +55 ±1.0

-35 to +48 ±0.1

This instruction uses a single excitation channel

since several hundred probes can be driven by

a single excitation output. For this reason,

Instruction 11 does not require a

"measurement/excitation" parameter.

A multiplier of 1 and an offset of 0 yields

temperature in degrees C.

PAR. DATA

NO. TYPE DESCRIPTION

01: 2 Repetitions

02: 2 Analog card number for first

measurement

03: 2 Single-ended channel

number for first

measurement

04: 2 Excitation card number for

first measurement

05: 2 Excitation channel number

for first measurement

06: 4 Input location of first

measurement

07: FP Multiplier

08: FP Offset

Input locations altered: 1 per repetition

*** 12 207 RELATIVE HUMIDITY PROBE ***

FUNCTION

This instruction applies a 3 VAC excitation

across Campbell Scientific's Model 207

Temperature and RH Probe, makes a fast

single ended measurement across a series

resistor on the 150 mV range, linearizes the

result with a 5th order polynomial and performs

the required temperature compensation before

outputting the result in % RH.

When measuring several probes, all the RH

elements should be connected sequentially.

Any temperature elements used for

compensating the respective RH value should

also be sequentially connected to make use of

the REP feature in Instruction 11.

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