Preface
MicroLogix 1000 Programmable Controllers User Manual
G–4
modem: Modulator/demodulator. Equipment that connects data terminal
equipment to a communication line.
modes: Selected methods of operation. Example: run, test, or program.
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 ladder programming, a symbol that will allow 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 ladder programming, a symbol that will
allow logic continuity (flow) if the referenced input is logic “1” when evaluated.
offset: The steady-state deviation of a controlled variable from a fixed point.
offline: Describes devices not under direct communication. For example, when
programming in APS.
one-shot: A programming technique that sets a bit for only one program scan.
online: Describes devices under direct communication. For example, when APS 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.
overall accuracy: The worst case deviation of the output voltage or current from
the ideal over the full output range is the overall accuracy. For inputs, the worst
case deviation of the digital representation of the input signal from the ideal over the
full input range is the overall accuracy
. This is expressed in percent of full scale.
pr
ocessor:
A Central Processing Unit. (See CPU.)
pr
ocessor file:
The set of program and data files used by the controller to control
output devices. Only one processor file may be stored in the controller at a time.
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