Rockwell Automation 1772-LV Mini-PLC - 2/15 Programmable Controller (Series B) Programming and Operations - Manual (Page 206)

Glossary
Appendix B
BĆ13
Program
A sequence of instructions to be executed by the PC processor to control a
machine or process.
Program Panel
A device for inserting, monitoring, and editing a program in a programmable
controller.
Program Scan Time
The time required for the PC processor to execute all instructions in the
program once. The program scan repeats continuously. The program monitors
inputs and controls outputs through the input and output image tables.
Programmable Controller
A solid state control system which has a user programmable memory for storage
of instructions to implement specific functions such as
I/O control logic, timing, counting, arithmetic, and data control logic, timing,
counting, arithmetic, and data manipulation. A PC consists of central processor,
input/output interface, memory, and programming device which typically uses
relay-equivalent symbols. PC is purposely designed as an industrial control
system which can perform functions equivalent to a relay panel or a wired solid
state logic control system.
PROM
Acronym for Programmable Read Only memory. A type of ROM that requires
an electrical operation to generate the desired bit or word pattern. In use, bits or
words are accessed on demand, but not changed.
Protected Memory
Storage (memory) locations reserved for special purposes in which data cannot
be entered directly by the user.
Put Instructions
A PC instruction which is used with a preceding get instruction to transfer data
from one data table word to another. The on and off states of all bits in the word
addressed by get are duplicated in the word addressed by put.
Rack
A PC chassis that contains modules (e.g., I/O rack or processor rack).
Rack Fault
1) A red diagnostic indicator which illuminates to signal a loss of
communication between the processor and any Remote I/o chassis. 2) The
condition which is based on the loss of communication.
RAM
Acronym for Random Access Memory. RAM is a type of memory that can be
accessed (read from) or loaded (written into) depending on the particular
addressing and operation codes generated internally in the PC.