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• current loop
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Computer terminal Historical
1
Typically terminals communicate with the
computer via a serial port, often using an
RS-232 or a current loop serial interface
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Railgun - Mathematical formula
1
as the length of the
current loop
increases
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Cathode - Etymology
He fundamentally defined his
arbitrary orientation for the cell as
being that in which the internal
current would run parallel to and in
the same direction as a hypothetical
magnetizing current loop around the
local line of latitude which would
induce a magnetic dipole field
oriented like the Earth's
1
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Modem - History
1
Modems grew out of the need to connect
teleprinters over ordinary phone lines
instead of the more expensive leased lines
which had previously been used for
current loop–based teleprinters and
automated telegraphs. In 1942, IBM
adapted this technology to their unit record
equipment and were able to transmit
punched cards at 25 bits/second.
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Anode - Etymology
1
He fundamentally defined his arbitrary
orientation for the cell as being that in
which the internal current would run
parallel to and in the same direction as a
hypothetical magnetizing current loop
around the local line of latitude which
would induce a magnetic dipole field
oriented like the Earth's
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Coilgun
1
Coilguns are distinct from railguns, as
the direction of acceleration in a
railgun is at right angles to the central
axis of the current loop formed by the
conducting rails
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RS-232 - Connectors
Presence of a 25-pin D-sub connector
does not necessarily indicate an RS-232C compliant interface. For example, on
the original IBM PC, a male D-sub was
an RS-232-C DTE port (with a nonstandard current loop interface on
reserved pins), but the female D-sub
connector on the same PC model was
used for the parallel Centronics printer
port. Some personal computers put nonstandard voltages or signals on some
pins of their serial ports.
1
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RS-232 - Related standards
1
A 20 mA current loop uses the absence of
20 mA current for high, and the presence
of current in the loop for low; this signaling
method is often used for long-distance and
optically isolated links
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Control flow - Early exit from loops
1
When using a count-controlled loop to
search through a table, it might be
desirable to stop searching as soon as
the required item is found. Some
programming languages provide a
statement such as break (most
languages), exit, or last (Perl), whose
effect is to terminate the current loop
immediately and transfer control to the
statement immediately following that
loop.
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Electrical reactance - Inductive reactance
1
An inductor consists of a coiled conductor.
Faraday's law of electromagnetic induction
gives the counter-emf (voltage opposing
current) due to a rate-of-change of
magnetic flux density through a current
loop.
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Alarm management - Alarm problem history
1
The sensors relayed their information to
the control instruments via 4-20 mA
current loop in the form of twisted pair
wiring
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Telex - Development
1
The first option, sometimes called local or
Current loop|loop service, provided a 60
milliampere loop circuit from the exchange
to the customer teleprinter
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Amazon tax - California
1
Ross, The San Francisco Chronicle,
January 19, 2011 This legislation will
close the current loophole in tax law
which has allowed out-of-state
companies to avoid collecting
California sales and use tax, stated
Skinner
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Attention - Neural correlates of attention
1
* Through top-down sensitivity control, higher
cognitive processes can regulate signal
intensity in information channels that
compete for access to working memory, and
thus give them an advantage in the process
of competitive selection. Through top-down
sensitivity control, the momentary content of
working memory can influence the selection
of new information, and thus mediate
voluntary control of attention in a recurrent
loop (endogenous attention).
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Magnetic field - History
1
From the outside, the field of a dipole
of magnetic charge has the exact
same form as that of a current loop
when both are sufficiently small.
Therefore, the two models differ only
for magnetism inside magnetic
material.
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Magnetic field - Amperian loop model and the B-field
After Oersted discovered that electric
currents produce a magnetic field and
Ampere discovered that electric currents
attracted and repelled each other similar to
magnets, it was natural to hypothesize that all
magnetic fields are due to electric current
loops. In this model developed by Ampere,
the elementary magnetic dipole that makes
up all magnets is a sufficiently small
Amperian loop of current I. The dipole
moment of this loop is where is the area of
the loop.
1
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Magnetic field - Magnetic torque on permanent magnets
1
The Amperian loop model also predicts
the same magnetic torque. Here, it is
the field interacting with the Amperian
current loop through a Lorentz force
described below. Again, the results are
the same although the models are
completely different.
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Magnetic moment - Current loop definition
Practitioners using the current loop
model generally represent the magnetic
field by the solenoidal field 'B',
analogous to the electrostatic field 'D'.
1
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Magnetic moment - Magnetic moment of a solenoid
1
A generalization of the above current
loop is a coil, or solenoid. Its moment
is the vector sum of the moments of
individual turns. If the solenoid has N
identical turns (single-layer winding)
and vector area 'S',
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Magnetic moment - Units
For example, in the Magnetic
moment#Current loop definition|current
loop definition, the area is measured in
square meters and I is measured in
Ampere (unit)|amperes, so the magnetic
moment is measured in ampere–square
meters (A m2)
1
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Magnetic moment - Force on a moment
force, proportional to the magnetic field
gradient, acting on the magnetic moment
itself. There has been some discussion on
how to calculate the force acting on a
magnetic dipole. There are two expressions
for the force acting on a magnetic dipole,
depending on whether the Magnet#Two
models for magnets: magnetic poles and
atomic currents|model used for the dipole is a
current loop or two monopoles (analogous to
the electric dipole).
1
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Magnetic moment - Force on a moment
1
The force obtained in the case of
a current loop model is
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Magnetic moment - Magnetic dipoles
1
A magnetic dipole is the limit of either a
current loop or a pair of poles as the
dimensions of the source are reduced to
zero while keeping the moment constant.
As long as these limits only applies to
fields far from the sources, they are
equivalent. However, the two models give
different predictions for the internal field
(see below).
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Dipole
1
For the current loop, the magnetic dipole
moment points through the loop
(according to the right hand grip rule), with
a magnitude equal to the current in the
loop times the area of the loop.
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Dipole
1
However, to the best of our knowledge,
the electron's magnetic moment is not
due to a current loop, but is instead an
intrinsic property of the electron
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Dipole
The only known mechanisms for the
creation of magnetic dipoles are by current
loops or quantum-mechanical spin
(physics)|spin since the existence of
magnetic monopoles has never been
experimentally demonstrated.
1
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Electricity meter - Communication methods
Often, meters designed for semiautomated reading have a serial port
on that communicates by infrared
LED through the faceplate of the
meter. In some multi-unit buildings, a
similar protocol is used, but in a wired
bus using a serial port|serial current
loop to connect all the meters to a
single plug. The plug is often near a
more easily accessible point.
1
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Building Automation - Types of inputs and outputs
1
Analog inputs are used to read a variable
measurement. Examples are temperature,
humidity and pressure sensor which could
be thermistor, Current loop#Processcontrol use|4-20 mA, 0-10 volt or platinum
resistance thermometer (resistance
temperature detector), or wireless
sensors.
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Programmable Logic Controller - Discrete and analog signals
1
Current loop|Current inputs are less
sensitive to electrical noise (i.e. from
welders or electric motor starts) than
voltage inputs.
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MEMS magnetometer - Voltage sensing
1
The location of the current loop enables a
more uniform Lorentz force distribution
compared with the aforementioned Ushape cantilever beam
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Universal asynchronous receiver/transmitter - Transmitting and receiving serial data
1
Historically, current (in
current loops) was used
in telegraph circuits
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EIA-232 - Related standards
1
A 20mA digital current loop interface
| current loop uses the absence of
20mA current for high, and the
presence of current in the loop for low;
this signaling method is often used for
long-distance and optical
isolator|optically isolated links
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Thermoelectric - Seebeck effect
This was because the metals
responded differently to the
temperature difference, creating a
current loop and a magnetic field
1
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IEC 62056
* IEC 62056-21:2002, Direct local data
exchange (3d edition of IEC 61107)
describes how to use COSEM over a local
port (optical or current loop)
1
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IEC 62056 - IEC 62056-21
1
The physical media are usually either
modulated light, sent with an LED and
received with a photodiode, or a pair
of wires, usually modulated by a
20mA current loop
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Highway Addressable Remote Transducer Protocol - Modes
1
In point-to-point mode, the digital part of
the HART protocol can be seen as a kind
of digital current loop interface.
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Curie temperature - Weiss domains and surface and bulk Curie temperatures
1
The angular momentum of an electron is
either +ħ/2 or - ħ/2 due to it having a spin
of ½, which gives a specific size of
magnetic moment to the electron; the
Bohr Magneton. Electrons orbiting
around the nucleus in a current loop
create a magnetic field which depends
on the Bohr Magneton and magnetic
quantum number. Therefore the
magnetic moments are related between
angular and orbital momentum and
affect each other. Angular momentum
contributes twice as much to magnetic
moments than orbital.
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State Grid Corp - History
1
It also has an alternating current loop
line in the Yangtze river delta, and three
longitudinal alternating current lines
that bring power to Southern China
from the Northern region.
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REXX - Repetitive loops
A program can break out of the current
loop with the leave instruction, which is the
normal way to exit a do forever loop, or
can short-circuit it with the iterate
instruction.
1
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Teleprinter - Teleprinter operation
1
More than two teleprinters could be connected to
the same wire circuit by means of a current loop.
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Teleprinter - Teletypesetter
1
In later years the incoming 6-bit current
loop signal was coupled directly into a
minicomputer or mainframe for storage,
editing, and eventual feed to a
phototypesetting machine.
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HP 2640 - Functionality
For example, more memory (providing
larger scrollback capability) could be easily
added, the serial interface could be
changed from RS-232 to current loop, etc
1
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PDP-11 - LSI-11
The CPU microcode includes a
debugger: firmware with a direct
serial interface (RS-232 or current
loop) to a Computer
terminal|terminal
1
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Dumb terminal - Popular VDUs
* RS232 serial ports (25-pin, ready to
connect to a modem, yet some
manufacturer-specific pin usage extended
the standard, e.g. for use with 20-mA
Digital current loop interface|current loops)
1
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Dumb terminal - Dumb and Intelligent Terminals
1
Typically terminals communicate with the
computer via a serial port via a null
modem cable, often using an EIA RS-232
or RS-422 or RS-423 or a Digital current
loop interface|current loop serial interface
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Teletype Model 33 - Interface
1
As the price of electronic terminals
dropped in the late 1970s, the current
loop was gradually replaced by an RS232 interface.
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PDP-8 - Input/Output
Over time I/O systems such as
DECtape|magnetic tape, RS-232 and
current loop dumb computer
terminal|terminals, punched card readers,
and magnetic disk|fixed-head disks were
added
1
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Java keywords - List
1
:Used to resume program execution at the
end of the current loop body. If followed by
a label, continue resumes execution at the
end of the enclosing labeled loop body.
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Stayin' Alive - Beginnings
1
After listening to the drum track of the
already-recorded Night Fever, the
group and producer Albhy Galuten
selected two bars from that track, rerecorded them as a recurrent loop on
a separate tape, and proceeded with
sessions for Stayin' Alive
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Dumb terminals - Early VDUs
* RS-232 serial ports (25-pin, ready to
connect to a modem, yet some
manufacturer-specific pin usage extended
the standard, e.g. for use with 20-mA
Digital current loop interface|current loops)
1
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SAE J1772 - Signaling
1
The pilot line circuitry examples in SAE
J1772:2001 show that the current loop
CP-PE is connected permanently via a
2740Ω resistor making for a voltage drop
to from +12V to +9V when a cable is
hooked up to the charging station which
activates the wave generator
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RSTS/E - Communication
1
The connection might be a local computer
terminal with a 20 Ampere|mA current loop
interface, an RS-232 interface (either local
serial port or remote connection via
modem), or by an ethernet connection
utilizing DECnet or LAT
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⛽ - Communications components
1
The technology for communicating with
gas pumps from a point of sale or other
controller varies widely, involving a
variety of hardware (RS-485, RS-422,
current loop, and others) and proprietary
software protocols. Traditionally these
variations gave pump manufacturers a
natural tie-in for their own point-of-sale
systems, since only they understood the
protocols.[http://www.ifsf.org/Software/
IFSF%20Management%20Intro%20%20V3.01.pdf IFSF Management Intro,
sec 1.1 Background history]
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Snubber - Electrical systems
Inductive elements are often
unintentional, but arise from the
current loops implied by physical
circuitry
1
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Intelligent buildings - Types of inputs and outputs
1
Analog inputs are used to read a variable
measurement. Examples are temperature,
humidity and pressure sensors which
could be thermistor, Current
loop#Process-control use|4-20 mA, 0-10
volt or platinum resistance thermometer
(resistance temperature detector), or
wireless sensors.
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Remote Terminal Unit - Analog inputs
An RTU can monitor analog inputs of
different types including 0-1mA, Current
loop#Analog|4–20mA current loop, 0–10V.,
±2.5V, ±5.0V etc.
1
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Access Control Systems - Access control system topologies
'1. Serial controllers.' Controllers are
connected to a host PC via a serial EIA485|RS-485 communication line (or via
20mA current loop in some older systems).
External RS-232/485 converters or internal
RS-485 cards have to be installed, as
standard PCs do not have RS-485
communication ports.
1
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Synchronous Data Link Control
1
or Current loop|loop facilities, on switched
or dedicated, Two-wire circuit|two-wire or
Four-wire circuit|four-wire circuits, and with
full-duplex and half-duplex operation..
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Switching amplifier - Electromagnetic interference
1
* Avoid inductive coupling from various current loops
in the power stage into the wiring.
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Signal conditioning - Applications
Types of devices that use signal
conditioning include signal filters,
instrument amplifiers, sample-and-hold
amplifiers, isolation amplifiers, signal
isolators, multiplexers, bridge
conditioners, analog-to-digital
converters, digital-to-analog converters,
frequency converters or translators,
voltage converters or inverter
(electrical)|inverters, frequency-tovoltage converters, voltage-to-frequency
converters, current-to-voltage
converters, current loop converters, and
charge converters.
1
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4-20 mA
In electrical signalling
(telecommunication)|signalling an
analog 'current loop' is used where a
device must be monitored or
controlled remotely over a pair of
conductors. Only one current level
can be present at any time.
1
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4-20 mA
1
Given its analog nature, current loops
are easier to understand and debug
than more complicated digital
fieldbuses, requiring only a handheld
digital multimeter in most situations.
Using fieldbuses and solving related
problems usually requires much more
education and understanding than
required by simple current loop
systems.
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4-20 mA
Additional digital communication to the
device can be added to current loop using
HART Protocol. Digital process buses
such as FOUNDATION Fieldbus and
Profibus may replace analog current
loops.
1
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4-20 mA - Process-control use
1
Since input terminals of instruments may
have one side of the current loop input tied
to the chassis ground (earth), analog
isolators may be required when
connecting several instruments in series.
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4-20 mA - Process-control use
(A 4-wire instrument has a power
supply input separate from the current
loop.) Another loop may contain two
passive chart recorders, a passive
pressure transmitter, and a 24 V battery
1
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4-20 mA - Long circuits
Analog current loops were
occasionally carried between
buildings by dry pairs in telephone
cables leased from the local telephone
company. 4–20mA loops were more
common in the days of analog
telephony. These circuits require endto-end direct current (DC) continuity.
DC continuity is not available over a
microwave radio, optical fibre, or a
multiplexed telephone circuit
connection.
1
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4-20 mA - Discrete control
1
These devices can be employed for any
remote control need a designer might
imagine. For example, a current loop could
actuate an evacuation Siren
(noisemaker)|siren or command
synchronized traffic signals.
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4-20 mA - Two-way radio use
1
The office would have a remote control
unit that would operate the taxi company
base station over a current loop circuit
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Fieldbus - Description
1
This would be the equivalent of the currently
used Current loop|4-20 mA communication
scheme which requires that each device has
its own communication point at the controller
level, while the fieldbus is the equivalent of
the current local area network|LAN-type
connections, which require only one
communication point at the controller level
and allow multiple (hundreds) of analog
signal|analog and Digital data|digital points to
be connected at the same time
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Pseudovector - Physical examples
1
Consider an electrical current loop in the
plane that inside the loop generates a
magnetic field oriented in the z direction
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List of computing and IT abbreviations - A
1
* Active current loop|ACL—
Active Current Loop
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Hydrogen line - Cause
1
This logic fails here because the electron
is not spatially displaced from the proton,
but encompasses it, and the magnetic
dipole moments are best thought of as tiny
current loops
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8085 - Development system
1
A lower cost SDK-85 System Design Kit
board was provided with an 8085 CPU,
8355 ROM containing a debugging
monitor program, 8155 RAM and 22 I/O,
8279 hex keypad and 8-digit 7-segment
LED, TTY (Teletype) 20mA current loop
serial interface. Pads were available for
one more 2Kx8 8755 EPROM and another
256byte RAM 8155 I/O Timer/Counter
could be optionally added. All data,
control and address signals were
available on dual pin headers and a large
prototype area was provided.
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Magnetic field strength - History
1
From the outside, the field of a dipole of
magnetic charge has the exact same form
as that of a current loop when both are
sufficiently small
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Tone remote - History
1960s two-way radio
remote control consoles
used direct current loops
1
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UART - Break condition
1
The spacing condition of a current loop
line is indicated by no current flowing, and
a very long period of no current flowing is
often caused by a break or other fault in
the line
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Digital current loop interface
For Digital signal|digital serial
communications, a 'current loop' is a
communication interface that uses
electrical current|current instead of voltage
for signaling. Current loops can be used
over moderately long distances (tens of
kilometres), and can be interfaced with
opto-isolator|optically isolated links.
1
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Digital current loop interface - History
1
A digital current loop uses the absence of
current for high (space or break), and the
presence of current in the loop for low
(mark)
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Digital current loop interface - Electrical characteristics
The maximum electrical
resistance|resistance for a current
loop is limited by the available
voltage. Current loop interfaces
usually use voltages much higher
than those found on an RS-232
interface, and cannot be
interconnected with voltage-type
inputs without some form of level
translator circuit.
1
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Digital current loop interface - Examples
1
* MIDI (Musical Instrument Digital Interface) is a
digital current loop interface.
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Digital current loop interface - Examples
1
* The HART Protocol is a digital current
loop interface designed to be compatible
with analog current loop wiring.
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Single-board microcontroller - Communications and user interfaces
1
Early systems might implement a serial port to
provide RS-232 or current loop
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Stellar magnetic field - Field generation
Because the major currents flow in the
direction of conductive mass motion
(equatorial currents), the major component
of the generated magnetic field is the
dipole field of the equatorial current loop,
thus producing magnetic poles near the
geographic poles of a rotating body.
1
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Exhibition Place - Public transit
The first loop began operations in 1916
and was located at the current loop
location. In 1923 the loop was relocated to
the southeast near the Princes' Gate. With
the construction of the National Trade
Centre it was re-located back to the
original location in 1996.
1
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Atlanta Marathon - Route
1
From 1997 to 2009, about 90% was run
along the same course used for the 1996
Summer Olympics, ending near Turner
Field (built as Centennial Olympic Stadium
in the A-FC stadium parking lot). The
current loop course, takes in many major
sites within Atlanta, including the Olympic
rings.
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Teletype Model 28 - Interface
1
There were different kinds of Model 28
interfaces that included Rotary Dial,
current loop and polar signaling.
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