Glossary of Terms: C

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Adjusting instrument for proper response.
The comparison of a measuring device (an unknown) against an equal or better standard. Test during which known values of Measurand are applied to the device under test and corresponding output readings are recorded under specified conditions.
Calibration Curve
Graphical representation of the calibration record.
Calibration Cycle
the application of known values of Measurand and recording of corresponding Output readings over the full or the specified portion of the Range, in an ascending and descending direction.
Calibration Offset
An adjustment to eliminate the difference between the indicated value and the actual value.
Change in energy or material required to make a unit change in a measured variable.
Capacitance Cs, Cause of Change
- Proximity to conductive objects

If an object of conductive material is located within the sensing distance of the sensor, it will form two series connected capacitances with sensor areas S and M. The series connected  capacitances are much larger than the capacitance of the undamped oscillator. Maximum sensing distance can be achieved with conductive objects like metals, water etc.

- Of non-conductive objects

If a non-conductive object is moved into the sensor field, the field will be amplified in relation to the relative permittivity (Er) of the material to be detected and thus increase capacitance Cs. As from a relative permittivity of Er = 81 (water), sensing distances can be achieved that are equivalent to those for conductive materials. The sensing distance is reduced for materials with a lower Er.

Material Relative
Permittivity (Er)
Material Relative
Permittivity (Er)
Air, Vacuum 1 Wood 2-7
Paper 1.2 - 3 Marble 8.4 - 14
Paraffin Oil 2.2 Alcohol 25
PVC 3 Methanol 33.5
Glass 3-5 Water 81
Capacitive Load
Leading load; predominantly capacitive, so voltage does not change direction until corresponding current does.
Capacitive Sensors
Sensing technique which uses the capacitance of a target (can be clear glass or liquids) to switch an output.
Circuit device that can store an electric charge. A typical capacitor has 2 conductors or electrodes separated by a layer of non-conducting material (dielectric). With conductors on opposite sides of the dielectric layer, oppositely charged by a source of voltage, the electrical energy of the charged system is stored in the polarized dielectric.
(a) To combine logic circuitry to get more complex logic or timing control. (Inputs and outputs are wired in series.) (b) Two or more controllers working together. The output of the master controller is the set point for the "slave" controller. A classic example is the control of a reactor (a large vessel with a steel jacket around it). The product temperature (master) controller's output is the setpoint of the jacket temperature (slave) controller.
Cascade Control
Control action where the output of one controller is setpoint of another controller. Can be used in a controller using two loops of control.
A substance that changes the rate of a chemical reaction but is itself not changed. Switch contact material sometimes acts as a catalyst, accelerating the formation of polymers on the contact surface.
The switch contact connected to the negative terminal of the power supply.
A manufacturer's mark that demonstrates compliance with European Union (EU) laws, primarily governing products sold in Europe.
Compliant with the essential requirements of European directives pertaining to safety and/or electromagnetic compatibility.
Formerly known as Centigrade. A temperature scale in which water freezes at 0°C and boils at 100°C at standard atmospheric pressure. The formula for conversion to Fahrenheit scale is: deg°F = (1.8*deg°C) + 32.
This is a European standards committee, similar to UL or NEMA. It covers standardized dimensions and operating characteristics.
The rapid On-Off cycling of an electromechanical relay or mercury displacement relay due to insufficient controller bandwidth. It is commonly caused by excessive gain, little hysteresis, and short cycle time.
A die (unpackaged semiconductor device) cut from a silicon wafer, incorporating semiconductor circuit elements such as resistors, diodes, transistors, and/or capacitors.
Clean Air
Ideal conditions. Climate-controlled or sterile area.
Clock Frequency (SSI)
For absolute encoders with synchronous serial interface (SSI), the clock frequency is the frequency of the clock signal during data transmission. The clock frequency is specified by the sequence electronics, and must be within the corresponding limits.
Clock + / Clock -
Control lines of the SSI interface for synchronous data transmission. Clock+ and clock- together form a current loop, for potential-free reception of the clock frequency in SSI encoders.
Close Range Shielding
The capacitive sensor responds to all materials whose relative permittivity Er is greater than 1 (air, vacuum). This means that dirt deposits and moisture on the sensor surface are also detected.
Closed Loop
Complete signal path in control system; represented as group of units connected in a manner that signal started at any point follows closed path and comes back to that point. Signal path includes forward path, feedback signal, and summary point.
Closed Loop Control
A control system in which all adjustments necessary to maintain the system occur automatically through a feedback signal from the sensor.
Code Reader
A code reader contains up to 6 identical inductive sensors. Advantage: common supply rail, quick installation, reduced distance between individual sensors, very compact
Code Switching Speed
Number of measuring steps per second for absolute multi-turn encoders. For encoders with 13 bit resolution and 400 kHz code switching frequency, the maximum rotational speed is 3,000 rpm.
The term used to express the simultaneous production of two useful forms of energy from one process, i.e. steam used to produce electricity and provide for space heating in the same process.
Cold Junction
Connection point between thermocouple metals and the electronic instrument.
Cold Junction Compensation
Electronic means to compensate for the effective temperature at the cold junction.
Color Sensors
With the color sensor, you can use color as the criteria for sorting, quality monitoring and automation processes.
Common Mode Rejection (CMR)
The ability of an electronic device to eliminate the effect of AC or DC noise between signal and ground. Normally expressed in dB at DC to 60Hz. See also Normal Mode Rejection.
Communications Address
Number assigned to instrument used in data message exchange.
Procedure of providing a supplemental device, circuit, or special materials to counteract known sources of error (e.g., ambient temperature change). Compensation is often related to temperature compensation only.
Complementary Output
Both N.O. and N.C. outputs are available for use. A circuit that provides sink or source capability with a single input. Output that can be both light operated and dark operated. (Also known as 4-wire DC controls.)
A process variable that represents the amount of one material in a solution, or gas.
When steam cools it first transitions to water vapor and then back into liquid water, the condensed liquid is called condensate.
Dedicated operation; keystroke sequences select and establish pertinent control data best suited for an application.
Connection Cables

For shaft encoders, equipped with a connector base, the appropriate connector can be ordered as an accessory. For encoders with cable connection, the standard length of cable provided is 2 m respectively 1 m. The sheathing material for the incremental encoder is PUR. The wire size is 0.14 mm2. The cable screen is connected to the housing respectively to the flange. The operating temperature range is -20°C to +85°C.

Permissible bending radius at 20 °C: cable with a PUR sheath 12x cable ø

Control Cycle
The rate at which the output signal is updated.
Control Action
Nature of change of output affected by input. Output can be signal or value of a manipu-lated variable. Input can be an actuating error signal, output of another controller, or control loop feedback signal when setpoint is constant.
Control Base
Unit remote from sensor in which amplification and conditioning of the input signal takes place. Usually contains a power supply and an output device.
Control Mode
Designates the mode in which controller will operate (such as Manual, Automatic with Local Setpoint, Automatic with Remote Setpoint, Manual Cascade).
Control Point
Value of controlled variable that you operate to maintain.
Controlled Variable
Quantity or condition of controlled medium that is measured and controlled.
Device that measures changes in controlled variable and indirectly maintains the controlled variable within present limits.
Controller Output – CO
Output signal from the controller.
Convergent Beam
A variation of the diffuse scanning mode. A photoelectric control whose optical system is key to its operation. It simultaneously focuses and converges a very small, intense beam to a fixed-focal point in front of the control. The control is essentially blind a short distance before and beyond this focal point. Convergent beam scanning is used to detect the presence or absence of small objects while ignoring nearby background surfaces.
Convertible Output
Output that can be wired either as Normally Open or Normally Closed, but not at the same time.
Corner Frequency
For first order time constants, the "corner frequency" is the frequency where the amplitude ratio starts to turn and the phase lag equals 45 degrees.
Corrective Factor
Mathematical factor that, when multiplied by the sensing distance of a given sensor, will adjust sensing distance for the different metals being used as targets.
The most suitable flexible coupling can be chosen from the data of a servo drive system. Resolution, acceleration and the desired positional precision must be considered. The lag angle can be judged from the torque stiffness. This torque might be considerable, if high dynamic drive systems are used. The inertia moment is specified on the product data pages.
Canadian Standards Administration
Time value of movement of free electrons. One ampere equals one coulomb per second. Conventional reference is opposite to direction of actual electron movement.
Current Consumption
Amount of current required to power a sensor or control (excluding load). See supply current.
Current Duplex
Control algorithm that provides a second current output (split range) or second current output via auxiliary output for heat cool zones.
Current Sinking
Output type such that when it is On, current flow is from the load into the device's output, then to ground. Output is Normally High. The sensor "sinks" current from the load through the sensor to ground. The load is connected between the positive lead of the supply and the output lead of the sensor.
Current Sourcing
an output type such that when it is On, current flow is from the device into the load. Output is Normally Low. The sensor "sources" current to the load. The load is connected between the output lead and the negative ground lead of the supply.
Current/Time Duplex
Variation of duplex with current active for 50% output and relay active for 50% output.
Cycle Time
Length of one time-proportional output relay cycle. The time, usually expressed in seconds, for a controller to complete one on/off cycle.
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