Glossary
Appendix D
D-8
Environment
In a systems context, the environment is anything that is not a part of the
system itself. Knowledge about the environment is important because of
the effect it can have on the system or because of possible interactions
between the system and the environment.
EPROM
Erasable Programmable Read Only Memory. A PROM that can be erased
with ultraviolet light, then reprogrammed with electrical pulses.
ERR
See Error Message.
Error Message (ERR)
The response to an opcode the industrial terminal cannot interpret.
Execution
The performance of a specific operation that is accomplished through
processing one instruction, a series of instructions, or a complete program.
Execution Time
The total time required for the execution of one specific operation.
False
As related to processor instructions, a reset logic state.
Fault
Any malfunction which interferes with normal application operation.
Fault Zone
An area in the program which alters the operation portion of the
application if a rack fault occur. Each fault zone is delimited by
fence code.
Feedback
The signal or data transmitted to the processor from a controlled machine
or process to denote its response to the command signal.
Fence Codes
Special program instructions which control and delimit specific program
areas such as fault zones.
FIFO
See First-In-First-Out.
F
