Campbell CR800 Series User Manual

Section 7. Installation
219
terminals VX1 and SE1. The following variables are preset by the program:
SimulatedRHSignal = 100, KnownRH = 0.
3. To start the 'calibration', set variable CalMode = 1. When CalMode
increments to 6, zero calibration is complete. Calibrated RHOffset will equal -
5% at this stage of this example.
4. To continue this example and simulate a zero-drift condition, set variable
SimulatedRHSignal = 105.
5. To simulate conditions for a 30-day-service calibration, again with desiccated
chamber conditions, keep variable KnownRH = 0.0. Set variable CalMode =
1 to start calibration. When CalMode increments to 6, simulated 30-day-
service zero calibration is complete. Calibrated RHOffset will equal -5.2 %.
FieldCal() Zero
'This program example demonstrates the use of FieldCal() in calculating and applying a zero
'calibration. A zero calibration measures the signal magnitude of a sensor in a known zero
'condition and calculates the negative magnitude to use as an offset in subsequent
'measurements. It does not affect the multiplier.
'
'This program demonstrates the zero calibration with the following procedure:
' -- Simulate a signal from a relative-humidity sensor.
' -- Measure the 'sensor' signal.
' -- Calculate and apply a zero calibration.
'You can set up the simulation by loading this program into the CR800 and interconnecting
'the following terminals with a jumper wire to simulate the relative-humidity sensor signal
'as follows:
' Vx1 --- SE1
'For the simulation, the initial 'sensor' signal is set automatically. Start the zero routine
'by setting variable CalMode = 1. When CalMode = 6 (will occur automatically after 10
'measurements), the routine is complete. Note the new value in variable RHOffset. Now
'enter the following millivolt value as the simulated sensor signal and note how the new
'offset is added to the measurement:
' SimulatedRHSignal = 1000
'NOTE: This program places a .cal file on the CPU: drive of the CR800. The .cal file must
'be erased to reset the demonstration.
'DECLARE SIMULATED SIGNAL VARIABLE AND SET INITIAL MILLIVOLT SIGNAL MAGNITUDE
Public SimulatedRHSignal = 100
'DECLARE CALIBRATION STANDARD VARIABLE AND SET PERCENT RH MAGNITUDE
Public KnownRH = 0
'DECLARE MEASUREMENT RESULT VARIABLE.
Public RH
'DECLARE OFFSET RESULT VARIABLE
Public RHOffset

Campbell CR800 Series Specifications

General

Brand	Campbell
Model	CR800 Series
Category	Data Loggers
Language	English