Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 251)

Glossary
Appendix B
BĆ15
Parallel Operation
A type of information transfer where all bits, bytes, or words are
handled simultaneously.
Parallel Output
Simultaneous availability of two or more bits, channels, or digits.
Parallel Transmission
The simultaneous transmission of bits which constitute a character.
Peripheral Equipment
Units which communicate with the programmable controller, but are not part of
the programmable controller. Example: a programming device or computer.
PR
See Preset Value.
Preset Value (PR)
The number of time intervals or events to be counted.
Primary Processor
A PC that controls all the I/O, but has a backup processor to take over system
operation in case it fails.
Process
1) Continuous and regular production executed in a definite uninterrupted
manner. 2) One or more entities threaded together to perform a requested
service.
Processor
The decision making data and storage sections of a programmable controller.
Program
A set of instructions used to control a machine or process.
Program Scan Time
The time required for the processor to execute the instructions in the program.
The program scan time may vary depending on the instructions and each
instruction’s status during the scan.
Program Storage
The portion of memory reserved for saving programs, routines, and subroutines.
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, report generation, Data Highway communication,
arithmetic, data and file manipulation. A programmable controller consists of a
central processor, input/output interface, and memory. A programmable
controller is designed as an industrial control system.