Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 508)

Glossary
G–4
negative logic: The use of binary logic in such a way that “0” represents the
voltage level normally associated with logic 1 (for example, 0 = +5V, 1 =
0V). Positive is more conventional (for example, 1 = +5V, 0 = 0V).
network: A series of stations (nodes) connected by some type of
communication medium. A network may be made up of a single link or
multiple links.
nominal input current: The current at nominal input voltage.
normally closed: Contacts on a relay or switch that are closed when the
relay is de–energized or the switch is de–activated; they are open when the
relay is energized or the switch is activated. In Instruction List
programming, a symbol that allows logic continuity (flow) if the referenced
input is logic “0” when evaluated.
normally open: Contacts on a relay or switch that are open when the relay
is de–energized or the switch is de–activated. (They are closed when the
relay is energized or the switch is activated.) In Instruction List
programming, a symbol that allows logic continuity (flow) if the referenced
input is logic “1” when evaluated.
one–shot: A programming technique that sets a bit for only one program
scan.
online: Describes devices under direct communication. For example, when
programming software is monitoring the program file in a controller.
operating voltage: For inputs, the voltage range needed for the input to be
in the On state. For outputs, the allowable range of user–supplied voltage.
output device: A device, such as a pilot light or a motor starter coil, that
receives data from the controller.
processor: A Central Processing Unit. (See CPU.)
program: The set of program and data files used by the controller to control
output devices. Only one program may be stored in the controller at a time.
program data: Provides data locations for output, input, status, bit, timer,
counter, control, and integer files.
program file: The area within a program that contains controller
information, the main program, interrupt subroutines, and any subroutine
programs.
program listing: A report containing a range of program files or a range of
rungs.
program mode: When the controller is not executing the program and all
outputs are de–energized.
program scan: A part of the controller’s operating cycle. During the scan
the ladder program is executed and the Output data file is updated based on
the program and the Input data file.