Analog to Digital. This electronic hardware converts an analog signal like
voltage, electric current, temperature, or pressure into a digital number that a
computer can process and interpret.
Sum of gauge pressure plus atmospheric pressure. Zero only in a perfect
Absolute Pressure Sensor
A sensor that measures input pressure in relation to zero pressure (a total
vacuum on one side of the diaphragm).
AC line frequency
The frequency of the alternating current power line measured in
Hertz (Hz), usually 50 or 60Hz.
Rate of change of velocity. Acceleration has two characteristics: magnitude
The hub of a wireless network. Also called a wireless router, wireless
gateway, or base station. Wireless clients connect to it, and traffic between
clients must travel through it.
Degree of conformity of an indicated value to an accepted standard value or
ideal value. The various errors (such as linearity, hysteresis, repeatability
and temperature shift) attributing to the accuracy of a device are usually
expressed as a percent of full scale output (Span)
Accuracy - Calibration Accuracy
Closeness between the value indicated by a measuring instrument
and a physical constant or known standard.
Accuracy - Control Accuracy
The ability to maintain a process at the desired setting. This
is a function of the entire system, including sensors, controllers,
heaters, loads, and inefficiencies.
Accuracy - Indication Accuracy
Closeness between the displayed value and a measured value.
Usually expressed as a + or -, a percent of span or number of
Accuracy - Setting Accuracy
Closeness between the value established by an input device, such
as a dial, and the desired value. Usually expressed as a percent of
span or number of digits.
The response of an output when the process variable is changed.
See also direct action, reverse action.
Depending on the My-Com type an activating force in the range of
30 cN to 100 cN is required to open the switch. Special versions may
require up to 250 cN.
The active area of a through beam sensor is equivalent to the
lens size of the emitter or receiver. The acceptance cone is larger.
This is important when considering alignment and operation near
Actual sensing range Tb
The actual sensing range Tb is between the adjusted nominal
sensing distance Tw and the blind region. The blind region is the
area immediately before the lens, in which target recognition cannot
be guaranteed. Within the actual sensing range, a standard Kodak
white target will always be detected.
The present value of the controlled variable.
Setpoint minus controlled variable at a given instant.
Controlled motor, relay, or solenoid in which electric energy is converted
into a rotary, linear, or switching action. Actuators can affect a change in
controlled variable by operating final control elements a number of times.
Simple and cost-effective. For simple and cost-effective
format change with an already existing external control
which works without fieldbus.
Compact and decentralized The actuator MSAA is equipped with an
absolute position encoder. Therefore, time-consuming reference runs
are not necessary.
The actuator tip of a standard My-Com is made of zirconium oxyde
ZrO2. Hard metal or ruby is used for a selected number of special
A numerical identifier for a controller when used in computer
The sensing distance of the sensor may be adjusted by means of a
potentiometer. See also potentiometer.
The LED indicates the intensity of the signal which has been
reflected by the object, as well as the switching state of the
output. LED on: The object is reliably detected with a signal
strength reserve of 50%. The output is switched. LED off: No target detected, output is not switched LED
flashing: Unreliable detection of the target. The output is
activated / switched.
The narrow sonic beam angle may be affected by strong air
streams in excess of 10 m/second.
Audible device or visible signal indicating a malfunction or off-normal
Electrical circuit that includes bell, horn, or similar device to signal
Alarm - Deviation Alarm
Warns that a process has exceeded or fallen below a certain
range around the set point. Alarms can be referenced at a fixed
number of degrees, plus or minus, from a set point.
Alarm - Loop Alarm
Any alarm system that includes high and low process deviation
band, dead band, digital inputs, and auxiliary control outputs.
Alarm - Process Alarm
Warns that process values exceed the process alarm setting. A
fixed value independent of set point.
Electrical current that reverses its direction of flow at
regular intervals and has alternately positive and negative values.
In the area. (1) light: Light in the area of the photosensor, but not
originating with the control light source. Ambient light can adversely affect
non-modulated control operation, and should be screened, if possible, from the
sensor; 2) Temperature: Average temperature of surrounding medium such as water,
air, or earth, into which the heat of the equipment is dissipated.
Conditions measured in the immediate area. The term implies that the
measurement is only accurate for the specific location it was taken. This term
can be applied to any unit of measure, such as temperature, pressure, humidity,
light intensity, etc.
Ambient light refers to any outside light such as sunlight
coming through windows or overhead room light.
The temperature of the encompassing atmosphere, including the
environment and air surrounding the equipment in use.
In a wireless network, a device connected to an antenna to increase the
signal strength and amplify weak incoming signals.
Continuous variable input.
An electrical output from a sensor that changes proportionately with any
change in input pressure, usually represents temperature, pressure, level, or
flow. Has the property of being continuously variable, as opposed to having
discrete states. Usually, the electrical current signal is of magnitude 4-20 mA
where 4 mA is the minimum point of span and 20 mA is the maximum point of span.
The transmission of data as a continuous signal, as opposed to
an on/off digital signal.
Decision logic for programming functions, where an output is produced only
when all inputs are present.
Sound waves, like light waves, are reflected from flat surfaces.
It is therefore possible that the reflected sonic beam from an
angled surface might be too small for the accurate recognition of a
target. The influence of tilting increases when the distance between
the sensor and the target increases. This effect can also be used to
advantage as shown here to remotely detect a target. The reflector
must be large enough and have smooth surfaces and edges.
Switch contact connected to the positive terminal of the power supply.
A device connected to a wireless transceiver that concentrates transmitted
and received radio waves to increase signal strength, and increase the effective
range of a wireless network.
This feature of the PID controller prevents the integral (reset)
circuit from operating when the temperature is outside the
proportional band, thus stabilizing the system.
One of several kinds of visible electrical discharge between separated
contacts of a switch. It is primarily a stream of electrons and is accompanied
by incandescent metal vapor.
The object has to approach the light beam laterally or head-on.
The combination of sensors and actuators using one or two common
bus cables considerably reduces the wiring costs. AS-Interface does
not require the user to generate additional software to operate the
bus system. The simple interface is what sets AS-Interface apart
from many other bus systems.
Since July 1, 2003 electrical equipment for hazardous areas may
only be sold and installed provided it has been designed according
to the ATEX guidelines as laid out in the specification paper
Atmospheric Pressure Compensation
Value of atmospheric pressure of process when using Relative Humidity
Loss or reduction of beam intensity as a result of environmental factors,
dust, humidity, steam etc.
For bumpless transfer, when transferring from local setpoint to remote
setpoint. Auto Bias calculates and adds a bias to remote Setpoint input each
time a transfer is made.
Auto (Automatic) Mode:
Mode where the controller calculates the output based its calculation using
the error signal (difference between setpoint and PV). Controller automatically
adjusts output to maintain setpoint at desired value.
Auto Zeroing Technique
Method used to automatically set the null point on a pressure sensor. This
is usually done by using a microprocessor to open a solenoid valve at a
predetermined time interval. This references atmospheric pressure to both sides
of the pressure sensor chip. The microprocessor reads the output voltage and
makes that the new null point. This method is used to eliminate errors due to
null offset and null temperature shift.
System that reacts to change or unbalance in one of its variables by
adjusting other variables to restore system to desired balance.
Mechanism, sold separately, to provide basic switches with easier means of
operation and adjustment and adapt switches to different operating motions by
supplying supplemental overtravel.
Generally a millivolt or voltage output configured to represent a controller
parameter (PV, input, setpoint, deviation, or control output).