Campbell Scientific CR23X Micrologger - Manual (Page 143)

SECTION 9. INPUT/OUTPUT INSTRUCTIONS
9-9
NOTE: The temperature value used in
compensating the RH value (Parameter 5)
must be obtained (see Instruction 11) prior
to executing Instruction 12 and must be in
Celsius.
The RH results are placed sequentially into the
input locations beginning with the first RH value.
In the 207 probe, the RH and temperature
elements use a common excitation line.
CAUTION: Never excite the 207 probe with
DC excitation because the RH chip will be
damaged.
A 1 before the excitation channel number (1X)
causes the channel to be incremented with
each repetition.
The maximum RH polynomial error is given here:
Curve Fit Error --
Range (%RH) Error (%RH)
10 - 100
±
4
15 - 94
±
1
PARAM. DATA
NUMBER TYPE DESCRIPTION
01: 2 Repetitions
02: 2 First single-ended
channel for RH
measurement
03: 2 Excitation channel
number
04: 4 Input location for first
compensating
temperature
measurement (°C)
05: 4 Input location for first
R.H. measurement
06: FP Multiplier
07: FP Offset
Input locations altered: 1 per repetition
*** 13 THERMOCOUPLE TEMPERATURE, ***
SINGLE-ENDED MEASUREMENT
FUNCTION
This instruction uses the selected thermocouple
calibration to calculate the thermocouple output
voltage at the reference temperature, then it
makes a SINGLE-ENDED VOLTAGE
MEASUREMENT (Section 13.2) on the
thermocouple and adds the measured voltage
to the calculated reference voltage, then
converts the voltage to temperature in °C. A
multiplier of 1 and an offset of zero yields
temperature in degrees Celsius. When using
the
±
10,
±
50, and
±
200 mV ranges, the
thermocouple inputs are tested to ensure that
the thermocouple is not open.
NOTE: Because of the open thermocouple
test, high output impedance sensors should
not be measured with P13 or P14.
To skip the measurement portion of Instruction
13 and apply the CSI polynomials to a millivolt
value in an input location, index parameter
three, input channel. The input location where
the thermocouple output (mV) is located is now
defined by parameter three. The thermocouple
must be measured with Instruction 1.
TABLE 9-4. Thermocouple Type Codes
Code Thermocouple Type
X1 T (copper - constantan) X = 0 Normal Measurement
X2 E (chromel - constantan) X = 8 TC input from A5B40 isolation
X3 K (chromel - alumel) (uses 5 V range)
X4 J (iron - constantan) X = 9 Output -99999 if out of common
X5 B (platinum - rhodium) mode range (Inst. 14 only)
X6 R (platinum - rhodium)
X7 S (platinum - rhodium)
X8 N (nickel - chromium)