Rockwell Automation 1766-L32AWA, User Manual

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Rockwell Automation Publication 1766-UM001O-EN-P - September 2021 299
Glossary
programmed instructions to perform required decision making and
computational functions.
Master Control Relay (MCR)
A mandatory hard-wired relay that can be de-energized by any series-
connected emergency stop switch. Whenever the MCR is de-energized, its
contacts open to de-energize all application I/O devices.
mnemonic
A simple and easy to remember term that is used to represent a complex or
lengthy set of information.
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 deactivated; they are open when the relay is energized or the
switch is activated. In ladder 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 deactivated. (They are closed when the relay is energized or the
switch is activated.) In ladder programming, a symbol that allows logic
continuity (flow) if the referenced input is logic “1” when evaluated.
off-delay time
The OFF delay time is a measure of the time required for the controller logic to
recognize that a signal has been removed from the input terminal of the
controller. The time is determined by circuit component delays and by any
filter adjustment applied.
offline
Describes devices not under direct communication.
offset
The steady-state deviation of a controlled variable from a fixed point.
off-state leakage current
When an ideal mechanical switch is opened (off-state) no current flows
through the switch. Practical semiconductor switches, and the transient
suppression components which are sometimes used to protect switches, allow
a small current to flow when the switch is in the off state. This current is
referred to as the off-state leakage current. To ensure reliable operation, the
off-state leakage current rating of a switch should be less than the minimum
operating current rating of the load that is connected to the switch.
on-delay time
The ON delay time is a measure of the time required for the controller logic to
recognize that a signal has been presented at the input terminal of the
controller.
one-shot
A programming technique that sets a bit for only one program scan.
online
Describes devices under direct communication. For example, when
RSLogix 500/RSLogix Micro 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.