Campbell Scientific CR23X Micrologger - Manual (Page 56)

SECTION 3. INSTRUCTION SET BASICS
3-2
to be changed. See Instructions 87 and 90,
Section 12, for more details.
To index an input location (4 digit integer) or set
port command (2 digit integer) parameter,
C
or "-" is pressed after keying the value but
before entering the parameter. Two minus
signs (--) will be displayed to the right of the
parameter.
3.5 VOLTAGE RANGE AND
OVERRANGE DETECTION
The voltage RANGE code parameter on
Input/Output Instructions is used to specify the
full scale range of the measurement and the
integration period for the measurement (Table
3.5-1).
The full scale range selected should be the
smallest that will accommodate the full scale
output of the sensor being measured. Using
the smallest possible range will result in the
best resolution for the measurement.
Four different integration sequences are
possible. The relative immunity of the
integration sequences to random noise is:
Slow 60 Hz rej. = Slow 50 Hz rej. > Fast 60 Hz
rej. = Fast 50 Hz rej. > 250
µ
s integ. The 60 Hz
rejection integration rejects noise from 60 Hz
AC line power. The 50 Hz rejection is for
countries whose electric utilities operate at 50
Hz (Section 13.1).
When a voltage input exceeds the range
programmed, the value which is stored is set to
the maximum negative number and displayed
as -99999 in high resolution or -6999 in low
resolution.
An input voltage greater than +8 volts on one of
the analog inputs will result in errors and
possible overranging on the other analog inputs.
Voltages greater than 16 volts may permanently
damage the CR23X.
3.6 OUTPUT PROCESSING
Most Output Processing Instructions have both
an Intermediate Data Processing operation and
a Final Data Processing operation. For
example, when the Average Instruction, 71, is
initiated, the intermediate processing operation
increments a sample count and adds each new
Input Storage value to a cumulative total
residing in Intermediate Storage. When the
Output Flag is set, the final processing
operation divides the cumulative total by the
number of samples to find the average. The
average is then stored in final storage and the
cumulative total and number of samples are set
to zero in Intermediate Storage.
Final Storage Area 1 (Sections 1.5, 2.1) is the
default destination of data output by Output
Processing Instructions. Instruction 80 may be
used to direct output to either Final Storage
Area 2 or to Input Storage.
Output Processing Instructions requiring
intermediate processing sample the specified
input location(s) each time the Output
Instruction is executed, NOT each time the
location value is updated by an I/O Instruction.
For example: Suppose a temperature
measurement is initiated by Table 1 which has
an execution interval of 1 second.
TABLE 3.5-1. Input Voltage Ranges and Codes
Resolution
Range Code Full Scale Range Differential*
Fast Slow Slow
250
µ
s 60 Hz 50 Hz
. Integ. Reject. Reject. .
10 20 30 Autorange **
11 21 31 ± 10 mV 0.33 µV
12 22 32 ±50 mV 1.67 µV
13 23 33 ±200 mV 6.66 µV
14 24 34 ±1000 mV 33.3 µV
15 25 35 ±5000 mV 166. µV
* Differential measurement, resolution for single-ended measurement is twice value shown.
**Autoranging may not adequately measure inputs with extremely noisy or rapidly changing signals.
Autoranging channels may occasionally measure on a higher range than is required.