Operator`s manual

A-1
APPENDIX A. GLOSSARY
ASCII: Abbreviation for American Standard
Code for Information Interchange
(pronounced "askee"). A specific binary
code of 128 characters represented by 7 bit
binary numbers.
BAUD RATE: The speed of transmission of
information across a serial interface,
expressed in units of bits per second. For
example, 9600 baud refers to bits being
transmitted (or received) from one piece of
equipment to another at a rate of 9600 bits
per second. Thus, a 7 bit ASCII character
plus parity bit plus 1 stop bit (total 9 bits)
would be transmitted in 9/9600 sec. =
.94ms or about 1000 characters/sec. When
communicating via a serial interface, the
baud rate settings of two pieces of
equipment must match each other.
DATA POINT: A data value which is sent to
Final Storage as the result of an Output
Instruction. Strings of data points output at
the same time make up Output Arrays.
EXECUTION INTERVAL: The time interval
between initiating each execution of a
program table. The execution interval will
be synchronized with the current 24 hour
time assuming that the table is executed at
midnight and every execution interval
thereafter. The table will be executed for
the first time at the first occurrence of the
execution interval after compilation. Any
time the clock is reset the execution interval
is resynchronized. See Section 1.1 for
information on the choice of an execution
interval.
EXECUTION TIME: The time that it actually
takes the 21X to execute an instruction or
group of instructions. If the execution time
of a program table exceeds the table's
execution interval, the program table will be
executed less frequently than programmed.
FINAL STORAGE: That portion of memory
allocated for storing Output Arrays. Final
Storage may be viewed as a ring memory,
with the newest data being written over the
oldest. Data in Final Storage may be
displayed using the *7 Mode or sent to
various peripherals (Section 2).
HIGH RESOLUTION: A high resolution data
value has 5 significant digits and may range
in magnitude from ±.00001 to ±99999. A
high resolution data value requires 2 Final
Storage locations (4 bytes). All Input and
Intermediate Storage locations are high
resolution. Output to Final Storage defaults
to low resolution; high resolution output
must be specified by Instruction 78.
INDEXED INPUT LOCATION: An input
location entered as an instruction parameter
may be indexed by keying "C" before
entering by keying "A"; two dashes (--) will
appear at the right of the display. Within a
loop (Instruction 87, Section 7), this will
cause the location to be incremented each
pass through the loop. Indexing is also
used with Instruction 75 to cause an input
location, which normally remains constant,
to be incremented with each repetition.
INPUT/OUTPUT INSTRUCTIONS:
Input/Output instructions are used to initiate
measurements and store the results in
Input Storage or to set Digital Control Ports
or Continuous Analog Output channels.
INPUT STORAGE: That portion of memory
allocated for storing the results of Input and
Processing instructions. The values in
Input Storage can be displayed and altered
from the *6 Mode.
INSTRUCTION LOCATION NUMBER: As
instructions are entered in a program table,
they are numbered sequentially. The
instruction location number is the number
giving an instruction's order in the program
table. When programming a table, the
instruction location number and a P (e.g.,
04: P00) prompts the user when it is time to
enter an instruction.