Rockwell Automation 1772-LV Mini-PLC - 2/15 Programmable Controller (Series B) Programming and Operations - Manual (Page 203)

Glossary
Appendix B
BĆ10
Magnetic Core Memory
(See core memory.)
Malfunction
Any incorrect functioning within electronic, electrical, or mechanical hardware.
(See fault.)
Manipulation
The process of controlling and monitoring data table bits or words by means of
the user’s program in order to vary application functions.
Master Control Relay
A mandatory hardwired relay which can be de-energized by any hardwired
series-connected emergency stop switch. Whenever the master control relay is
de-energized, its contacts must open to de-energize all application I/O devices.
WARNING: The master control relay must never be replaced by
MCR fence codes.
MCR Instructions
User-programmed fence codes for MCR zones.
MCR Zones
user program areas in which all non-retentive outputs can be turned OFF
simultaneously. Each MCR zone must be delimited and controlled by MCR
fence codes (MCR instructions).
WARNING: MCR FENCE CODES must never replace the
master control relay hardware.
Memory
A grouping of circuit element which has data storage and retrieval capability.
Memory Module
A processor memory storage module consisting of memory storage and capable
of storing a finite number of words.
Message
A meaningful combination of alphanumeric characters which establishes the
content and format of a report. it must be entered into PC memory by means of
a data terminal keyboard.
Mode
A selected method of operation (e.g., run, test, or program).