Campbell CR23X, Operator'S Manual

Page: 243 / 374

APPENDIX A. GLOSSARY
A-3
PRINT PERIPHERAL: See Print Device.
PROCESSING INSTRUCTIONS: These
Instructions allow the user to further process
input data values and return the result to Input
Storage where it can be accessed for output
processing. Arithmetic and transcendental
functions are included in these Instructions.
PROGRAM CONTROL INSTRUCTIONS:
Used to modify the sequence of execution of
Instructions contained in Program Tables; also
used to set or clear flags.
PROGRAM TABLE: That portion of memory
allocated for storing programs consisting of a
sequence of user instructions which control
data acquisition, processing, and output to Final
Storage. Programming can be separated into 2
tables, each having its own user-entered
Execution Interval. A third table is available for
programming subroutines which may be called
by instructions in Tables 1 or 2. The
1
and
2
Modes are used to access Tables 1
and 2. The 3 Mode is used to access
Subroutine Table 3. The length of the tables is
constrained only by the total memory available
for programming (Section 1.5). Tables 1 and 2
have independent execution intervals. Table 1
execution has the higher priority; it may interrupt
Table 2.
RING LINE (PIN 3): Line pulled high by an
external device to "awaken" the CR23X.
SAMPLE RATE: The rate at which
measurements are made. The measurement
sample rate is primarily of interest when
considering the effect of time skew (i.e., how
close in time are a series of measurements).
The maximum sample rates are the rates at
which measurements are made when initiated
by a single instruction with multiple repetitions.
SIGNATURE: A number which is a function of
the data and the sequence of data in memory.
It is derived using an algorithm which assures a
99.998% probability that if either the data or its
sequence changes, the signature changes.
SYNCHRONOUS: The transmission of data
between a transmitting and receiving device
occurs as a series of zeros and ones. For the
data to be "read" correctly, the receiving device
must begin reading at the proper point in the
series. In synchronous communication, this
coordination is accomplished by synchronizing
the transmitting and receiving devices to a
common clock signal (see Asynchronous).
TABLE OVERRUNS: Skipped scans occurring
when the CR23X program is too long for the
execution interval. Table overruns can cause
errors in pulse measurements.
THROUGHPUT: The throughput rate is the
rate at which a measurement can be made,
scaled to engineering units, and the reading
stored in Final Storage. The CR23X has the
ability to scan sensors at a rate exceeding the
throughput rate (see SAMPLE RATE). The
primary factor affecting throughput rate is the
amount of processing specified by the user. In
normal operation, all processing called for by an
instruction must be completed before moving on
the next instruction. The maximum throughput
rate for a fast single-ended measurement is
approximately 192 measurements per second
(12 measurements, repeated 16 times per
second). This rate is possible if the CR23X's
self-calibration function is suspended (this is
accomplished by entering Instruction 24 into
Program Table 2 while leaving the Execution
Interval 0 so Program Table 2 never
executes).
When the self-calibration function is operating,
the maximum throughput rate for a fast, single-
ended measurement is 192 measurements per
second (12 measurements, 16 times per
second).