Some standard content:
Industry Standard of the People's Republic of China
Common Terms and Definitions
for Measurement and Control System DesignHG/T20699-2000bZxz.net
Main Editor: China Huanqiu Chemical Engineering CorporationApproved by: State Administration of Petroleum and Chemical IndustryImplementation Date: June 1, 2001
National Chemical Engineering Construction Standard Editing Center (formerly the Engineering Construction Standard Editing Center of the Ministry of Chemical Industry) 2001 Beijing
1 General Provisions
The purpose of compiling this standard is to unify the basic terms and definitions in the application and engineering design of automatic control systems and instruments.
1.0.2 Content and Scope of Application
Chapter 2 Measurement and Instrument Characteristic Terms
These terms are related to measurement and its concepts, as well as the performance characteristics of instruments and systems. Chapter 3 Process Control Terms
These terms are related to control and its concepts, as well as the functions of control systems and the relationship between signals. Chapter 4 Industrial Automation Instrumentation Terms
These terms are related to instruments and their concepts.
Chapter 5 Digital Technology and Distributed Control System Terms These terms are related to digital technology and its concepts, as well as hardware and software of distributed control systems. Chapter 6 Automatic Control Design Terms
These terms are related to automatic control engineering design.
1.0.3 Relevant standards
GB/T17212-1998
JB/T8218-1999
JB/T9268-1999
IEC902-1987
ISA -S5. 1 -1984
"Terms and Definitions for Industrial Process Measurement and Control" "Terms for Actuators"
"Terms for Distributed Control Systems"
"INDUSTRIAL-PROCESSMEA SUREMENT AND CONTROL TERMS AND DEFINITIONS"
"INSTRUMENTATION SYMBOLS AND IDENTIFICATION) When implementing these provisions, the provisions of the relevant current national standards shall also be complied with. 349
2 Terminology of Measurement and Instrument Characteristics
2.0.1 (Measurable) quantity quantity a property of a phenomenon, object or substance that can be distinguished qualitatively and determined quantitatively. 2.0.2 variable variable
a quantity or state whose value can be changed and is usually measurable. 2.0.3 (Measurement) unit unit (of measurement) a specific quantity selected by agreement for the quantitative expression of quantities with the same dimension. 2.0.4 (Measurement) system of units (of measurement) a set of units established for a given system of quantities. For example: International System of Units (SI): CCS system of units. Note: A system of units includes a set of selected basic units and derived units determined by definition equations and proportional factors. 2.0.5 (Quantity) value value (of a quantity) a quantity expressed by a number and an appropriate unit of measurement. For example: 5.3m; 12kg; -40℃. 2.0.6 True value true value
The assumed theoretical value of a variable that closely defines it.
Note 1. The true value of a quantity is an ideal concept and is usually unknowable. 2. In practice, the so-called "conventional true value" is used. 2.0.7 Conventional true value conventional true value A quantity value that can replace the true value for certain purposes. Note: Generally speaking, the conventional true value is considered to be very close to the true value, and for certain purposes, the difference can be ignored. 2.0.8 Measurement
measurement
A set of operations for the purpose of determining the value of a quantity. 2.0.9 Static measurement statiemeasurement The measurement of a quantity whose value can be considered constant during the measurement. Note: The term "static" applies to the measured quantity, not to the measurement method. 2.0.10 Dynamic measurement dynamicmeasurement The measurement of the instantaneous value or the value that changes over time of a (variable) quantity. Note: The term "dynamic" applies to the measured quantity, not to the measurement method. 2.0.11 measurand, measured quantity the quantity being measured.
measuredvariable
measuredvariable
the quantity, characteristic or state being measured.
Note: the measured variable is usually temperature, pressure, flow, speed, etc. 2.0.13 input variableinput variable the variable input to the instrument.
2.0.14 output variableoutputvariable the variable output by the instrument.
2.0.15 measured value
measured value
the quantity expressed in numbers and units of measurement, obtained from the information obtained by the measuring device at a specified moment under specified conditions.
2.0.16 influencequantityinfluencequantity the quantity that is not a measurand but affects the measured value or the value indicated by the measuring instrument. For example: ambient temperature, frequency of the measured AC voltage.
2.0.17 Signalsignal
A physical variable whose one or more parameters carry information about one or more variables represented by the signal. measurement signal
2.0.18 Measurement signal
A signal that represents the measured quantity in a measurement system. analogue signal
Analog signal
A signal whose information parameter can be represented by all values within a given range. 2.0.20
Digital signaldigital signal
A signal whose information parameter can be represented by any value in a set of discrete values represented by a number. standardized signal
Standardized signal
A signal with standardized upper and lower range values. For example: 4mA~20mA (dc)
20kPa~100kPa
2.0.22 Input signalinput signal
A signal applied to the input of a device, component or system. 2.0.23 Output signal output signal
A signal sent by a device, component or system. quantified signal
2.0.24 Quantized signal
A signal with quantized information parameters.
2.0.25 Binary signal binarysignal A quantized signal with only two values.
2.0.26 Result of measurement The value of the measured quantity obtained by the measurement.
Note: 1. When the term "measurement result" is used, it should be clear whether it is an indication, an uncorrected result or a corrected result, and whether several observations have been averaged.
2. A complete description of the measurement result should include: information about the measurement uncertainty and information about the corresponding influencing quantity values. 2.0.27 Indication (of ameasuring instrument) The value of the measured quantity provided by the measuring instrument. 2.0.28 Accuracy of measurement
Synonym: Precision of measurement
The degree of agreement between the measurement result of the measured quantity and the (agreed) true value. Repeatability of measurement2.0.29 Measurement repeatability
The degree of consistency between the results of multiple consecutive measurements of the same measured variable under the same measurement method, the same observer, the same measuring instrument, the same location, the same working conditions and repeated within a short period of time. 2.0.30 Errorerror
The algebraic difference between the measured value and the true value of the measured variable. Note: 1. The error is positive when the measured value is greater than the true value. Error = measured value - true value
2. When the error is listed on the data sheet of an instrument or device, the calibration method of the instrument or device must be specified. 2.0.31 Absolute error
absoluteerror
The measurement result minus the (agreed) true value of the measured variable. 2.0.32 Relative error
relativeerror
The absolute error divided by the (agreed) true value of the measured variable, 2.0.33 Random error
randomerror
The part of the measurement error whose variation is unpredictable during multiple measurements of the same measurand. 2.0.34 Systematic error
systematic error
Error whose absolute value and sign remain constant or change according to a fixed rule when the conditions change during multiple measurements of the same given value. 2.0.35 Correction correction
The value that must be added algebraically to the uncorrected measurement result in order to obtain the corrected result, which value is the opposite of the known part of the systematic error.
2.0.36 Correction factor correctionfactorThe numerical factor by which the uncorrected measurement result is multiplied to compensate for the systematic error. 2.0.37 Arithmetic mean arithmetic meanThe quotient obtained by dividing the algebraic sum of n measurements of a quantity by n. 2.0.38 Performance characteristics performance characteristicsThe relevant parameters and their quantitative expressions that determine the function and capability of a device under static or dynamic conditions or as a result of a specific test.
2.0.39 Reference performance characteristicreferenceperformancecharacteristic Performance characteristic obtained under reference working conditions. 2.0.40 Rangerange
The numerical interval defined by the upper and lower limits of the quantity under study. Note: The term "range" is often modified. For example, it can be applied to the measured variable or working conditions.measuringrange
Measuring range
The interval determined by two values of the measured quantity measured with specified accuracy.measuringrangelowerlimit2.0.42
The lowest value of the measured variable to which the device can be adjusted and measured with specified accuracy.measuringrangeupperlimit rangehigherlimit2.0.43
The highest value of the measured variable to which the device can be adjusted and measured with a specified accuracy. 2.0.44
Span
The algebraic difference between the upper and lower limits of a given range. For example: when the range is -20°C to 100°C, the span is 120°C. 2.0.45
Scale
A set of ordered scale marks and all related numbers that form part of the indicating device. 6 Scale rangescalerange
The range defined by the scale start and end values. 2.0.47 Linear scalelinear scale
A scale in which the spacing between each scale grid and the corresponding grid value is in a constant proportional relationship. Note: A linear scale in which the spacing between scale grids is a constant is called a regular scale. 2.0.48 Nonlinear scalenonlinearscaleA scale in which the spacing between each scale grid and the corresponding grid value is in a non-constant proportional relationship. Note: Some nonlinear scales have special names, such as logarithmic scale and square law scale. 2.0.49 Zero of a measuring instrumentWhen any auxiliary energy required for the operation of the measuring instrument is connected and the measured value is zero, the direct indication of the instrument353
2.0.50 Instrument constantinstrumentconstantIn order to obtain the indication of the measuring instrument, a coefficient must be multiplied by the direct indication. Note: When the direct indication is equal to the measured value, the constant of the measuring instrument is 1. 2.0.51 Characteristic curvecharacteristic curve is a curve showing the functional relationship between the steady-state value of the output variable of a system or device and an input quantity, at which time the other input variables are kept at a specified constant value. Note: When other input variables are treated as parameters, a set of characteristic curves can be obtained. 2.0.52 adjustment adjustment
the operation of making the output of a device or instrument as consistent as possible with the expected specified characteristic curve. 2.0.53 calibration calibration
the set of operations that establish the relationship between the measured value and the corresponding output value of the device under specified conditions. 2.0.54 calibration curve calibration curve is a curve showing the relationship between the measured value and the corresponding value actually measured by the device under specified conditions. sensitivity sensitivity
the change in the response of the measuring instrument divided by the corresponding change in the stimulus. accuracy
the degree of consistency between the measurement result and the (agreed) true value of the measured value. 2.0.57
Accuracy limit
accuracyrating
The limit value of the inaccuracy of a particular model of device that can be guaranteed in the specification. 2.0.58Basic error
intrinsicerror
Also known as inherent error.
The indication error of the instrument under reference conditions. 2.0.59
Conformity
The degree of fit when the calibration curve approaches the specified characteristic curve (straight line, logarithmic curve, parabola, etc.). Conformity error conformityerror
The absolute value of the maximum deviation between the calibration curve and the specified characteristic curve. Linearity linearity
The degree of fit when the calibration curve approaches the specified straight line. Linearity error linearityerror
The absolute value of the maximum deviation between the calibration curve and the specified straight line. 2.0.63
dead band
The finite range of values within which a change in the input variable does not cause any perceptible change in the output variable. 2.0.64stability
The ability of an instrument to maintain its performance characteristics unchanged for a specified time under specified operating conditions. 2.0.65reliability
The ability of a device to perform its specified functions under specified conditions and within a specified time. 2.0.66drift
The gradual and undesirable change in the input-output relationship of a device over a period of time that is not caused by external influences on the device.
pointdrift
2.0.67pointdrift
The change in output corresponding to a constant input within a specified time under specified reference operating conditions. 2.0.68zerodrift
zerodrift
Abbreviated as zerodrift
Point drift on the lower limit of the range. When the lower limit is not zero, it is also called starting drift. 2.0.69 Repeatability repeatability
Under the same working conditions, the output values of the instrument measured multiple times in the same direction for the same input value are consistent with each other.
Note: Repeatability should not include hysteresis and drift. Repeatability error repeatabilityerror2.0.70
Under the same working conditions, when moving the full range in the same direction, the algebraic difference between the limit values obtained by measuring the output multiple times in a short period of time for the same input value. Span error spanerror
The difference between the actual output range and the specified output range. Note: The span error is usually expressed as a percentage of the specified output range. 2.0.72 Span shift The change in the output range caused by some influence. 2.0.73 Zero error
zeroerror
Under the specified conditions of use, the difference between the actual output value and the lowest value of the specified output range when the input is at the lower limit of the range.
Note: Zero error is usually expressed as a percentage of the specified output range. 2.0.74 Zero shift (offset) zeroshift The change in output value caused by some influence when the input is at the lower limit of the range. Note: Zero shift is usually expressed as a percentage of the specified output range. 355
2.0.75 Error of indication error of indication The indication of the instrument minus the (conventional) true value of the measured value. 2.0.76 Fiducial error
The indication error of the instrument divided by the specified value,
Note: This specified value is often called the reference value, for example: it can be the upper limit of the instrument's range or range, etc. 2.0.77 Mean time between failures
mean time between failures (MTBF) The average length of time between adjacent failures under specified conditions during the rated life of the functional unit. Mean time to repair
mean time to repair (MTTR)
Average time required for fault repair
Failure
The termination of the ability of a functional unit to achieve its specified function. Fault
An unexpected state that causes a functional unit to be unable to achieve its specified function. Function
The purpose or action completed by a device.
Samplingsampling
The process of taking the value of a measured quantity at a certain time interval. 2.0.83 Sampling ratesamplingrate The frequency of sampling the measured quantity, that is, the number of samples per unit time. 2.0.84 Sampling periodsamplingperiod The interval between two actual measurements in a periodic sampling control system. 2.0.85 Scan scan
Periodically sample a number of variables in a predetermined manner. The function of a scanning device is usually used to determine the state or value of a variable.
2.0.86 Scan rate
scanrate
The access rate of a series of analog input channels, expressed in the number of input channels per second.
2.0.87 Delay
Also known as dead time.
dead time
The time from the moment the input quantity changes to the moment the instrument output quantity begins to change. 2.0.88 Time constant
timeconstant
In a first-order linear system caused by a step or pulse input, the time required for the output to complete 63.2%356
of the total rise or fall.
Edamping
The dissipation of system energy during motion. Periodic damping
periodic damping, underdamping2.0.90
Also called underdamping
Damping with overshoot in step response
2.0.91 Aperiodic damping
Aperiodic damping, overdampingAlso called overdamping.
Damping with no overshoot in step response.
2.0.92 Damping factor
damping factor
In the free oscillation of a second-order linear system, the ratio of the larger amplitude to the smaller amplitude of a pair of (opposite) continuous swings of the output near the final steady-state value. 2.0.93 Noise
Harmful disturbance added to the signal causing its components to be masked. 2.0.94 Input impedanceinputimpedanceThe impedance between the input terminals of the instrument.
2.0.95 Output impedanceoutput impedanceThe impedance between the output terminals of the instrument.
2.0.96 load impedance load impedance the sum of the impedances of all devices and connecting wires connected to the output of the meter. 357
3.0.1 control
control
process control terminology
purposeful action on or within a system to achieve specified objectives. 3.0.2 process control process control
manipulation of variables that affect process conditions to achieve specified objectives. 3.0.3 automatic control automatic control control without direct or indirect human manipulation of terminal control elements. 3.0.4 manual control manual control
control by direct or indirect human manipulation of terminal control elements. NOTE: In industrial processes, manual control is accomplished by standardized signals. 3.0.5 monitoring
monitoring
observation of the operation of a system or part of a system to confirm correct operation and detect incorrect operation, which is accomplished by measuring one or more variables of the system and comparing the measured values with specified values. 3.0.6 Supervision
supervision
The control and monitoring operations of a system, including, where necessary, operations to ensure reliability and safety protection. 3.0.7 Loop
The combination of two or more instruments or control functions and the transmission of signals between them, so as to measure and control process variables.
3.0.8 Control hierarchy controlhierarchy A graphical representation of the relationship between different control (automation) levels arranged in increasing complexity of the main control system. 3.0.9 Control algorithm controlalgorithm A mathematical representation of the control action required to be performed. 3.0.10 Control system controlsystem
A system that achieves a predetermined state by precisely guiding or manipulating one or more variables. 3.0.11 Automatic control system automaticcontrol system A control system that operates without human intervention. It is divided into a master control system and a controlled system. 3.0.12 Master control system controllingsystem A system consisting of all the elements that control the controlled system. 358
Note: In feedback control, all elements in the feedback path are included. Controlled system
controlledsystem
The system that is controlled.
Real-time control systemreal-timecontrolsystemA computer control system that can respond quickly to inputs - quickly detect and process them, and can provide output operation signals in a timely manner.
Control loop
controlloop
A combination of components consisting of a comparison element, a corresponding forward path, and a corresponding feedback path. Note: Sometimes a control loop can also include other loops, in which case it is called a main loop, and the other loops it contains are called small loops, sub-loops, sub-loops, auxiliary loops, or local loops. masterloop
5mainloop
A control loop that controls the main controlled variable. The output variable of its main controller is the reference variable of the slave controller.
slaveloop
A loop in which the slave controller controls the slave controlled variable. 3.0.18actualvalueactualvalue
The value of a variable at a given moment.
desiredvaluedesiredvalue
The value of a variable required at a given moment under specified conditions. Setpointsetpoint
The signal representing the reference variable.
3.0.21controlledvariableThe output variable of the controlled system.
3.0.22manipulated(variable)quantity
manipulatedvariable
The output variable of the master control system, and also the input variable of the controlled system. 3.0.23referencevariableThe input variable for the master control system to set the desired value of the controlled variable. Note: 1. The reference variable can be set manually, automatically or by program. 2. The reference variable is usually expressed in the same units as the controlled variable. 3.0.24referencesignalreferencesignalThe signal derived from the reference variable and compared with the feedback signal on the comparison element. 3.0.25feedbacksignalfeedbacksignal35987Time lag
Also called dead time.
dead time
The time from the moment the input changes to the moment the output of the instrument starts to change. 2.0.88Time constant
timeconstant
In a first-order linear system caused by a step or pulse input, the time required for the output to complete 63.2%356
of the total rise or fall.
Edamping
The dissipation of system energy during motion. Periodic damping
periodic damping, underdamping2.0.90
Also called underdamping
Damping with overshoot in step response
2.0.91Aperiodic damping
aperiodic damping, overdampingAlso called overdamping.
Damping with no overshoot in step response.
2.0.92 Damping factor
damping factor
The ratio of the larger amplitude to the smaller amplitude of a pair of (opposite) successive swings of the output about the final steady-state value in the free oscillation of a second-order linear system. 2.0.93 Noise
An unwanted disturbance superimposed on a signal causing its components to be masked. 2.0.94 Input impedanceinput impedanceThe impedance between the input terminals of a meter.
2.0.95 Output impedanceoutput impedanceThe impedance between the output terminals of a meter.
2.0.96 Load impedanceload impedanceThe sum of the impedances of all devices and connecting wires connected to the output terminals of a meter. 357
3.0.1 Control
control
Process control terminology
A purposeful action on or within a system to achieve a specified goal. 3.0.2 Process controlprocesscontrol
The manipulation of variables that affect process conditions in order to achieve specified objectives. 3.0.3 Automatic controlautomaticcontrolControl without the need for direct or indirect human manipulation of terminal control elements. 3.0.4 Manual controlmanualcontrol
Control by direct or indirect human manipulation of terminal control elements. Note: In industrial processes, manual control is accomplished through standardized signals. 3.0.5 Monitoring
monitoring
Observing the operation of a system or part of a system to confirm correct operation and detect incorrect operation, which is accomplished by measuring one or more variables of the system and comparing the measured values with specified values. 3.0.6 Supervision
supervision
The control and monitoring operations of a system, including operations to ensure reliability and safety protection when necessary. 3.0.7 Loop
The combination of two or more instruments or control functions and the transmission of signals between them, thereby measuring and controlling process variables.
3.0.8 Control hierarchy controlhierarchy A graphical representation of the relationship between different levels of control (automation) arranged in increasing order of complexity of the master control system. 3.0.9 Control algorithm controlalgorithm A mathematical representation of the control action required to be performed. 3.0.10 Control system controlsystem
A system that achieves a predetermined state by precisely guiding or manipulating one or more variables. 3.0.11 Automatic control system automaticcontrol system A control system that operates without human intervention. It is divided into a master control system and a controlled system. 3.0.12 Master control system controllingsystem A system consisting of all the elements that control the controlled system. 358
Note: In feedback control, all elements in the feedback path are included. Controlled system
controlledsystem
A system that is controlled.
Real-time control system real-time controlsystem A computer control system that can respond quickly to inputs - rapid detection and rapid processing, and can provide output operation signals in a timely manner.
Control loop
controlloop
A combination of elements consisting of a comparison element, a corresponding forward path and a corresponding feedback path. Note: Sometimes a control loop can also include other loops. In this case, it is called a master loop, and the other loops it contains are called small loops, sub-loops, sub-loops, auxiliary loops or local loops. masterloop
5Master loop
A control loop that controls the main controlled variable. The output variable of its main controller is the reference variable of the slave controller.
Slave loop
A loop in which the slave controller controls the slave controlled variable. 3.0.18Actual valueactualvalue
The value of a variable at a given moment.
Expected valuedesiredvalue
The value of a variable required at a given moment under specified conditions. Setpointsetpoint
A signal representing the reference variable.
3.0.21Controlled variablecontrolledvariableThe output variable of the controlled system.
3.0.22 Manipulated variable
manipulated variable
The output variable of the master control system, which is also the input variable of the controlled system. 3.0.23 Reference variablereferencevariableThe input variable used by the master control system to set the expected value of the controlled variable. Note: 1. The reference variable can be set manually, automatically or by program. 2. The reference variable is usually expressed in the same units as the controlled variable. 3.0.24 Reference signalreference signalThe signal derived from the reference variable and compared with the feedback signal on the comparison element. 3.0.25Feedback signal35987Time lag
Also called dead time.
dead time
The time from the moment the input changes to the moment the output of the instrument starts to change. 2.0.88Time constant
timeconstant
In a first-order linear system caused by a step or pulse input, the time required for the output to complete 63.2%356
of the total rise or fall.
Edamping
The dissipation of system energy during motion. Periodic damping
periodic damping, underdamping2.0.90
Also called underdamping
Damping with overshoot in step response
2.0.91Aperiodic damping
aperiodic damping, overdampingAlso called overdamping.
Damping with no overshoot in step response.
2.0.92 Damping factor
damping factor
The ratio of the larger amplitude to the smaller amplitude of a pair of (opposite) successive swings of the output about the final steady-state value in the free oscillation of a second-order linear system. 2.0.93 Noise
An unwanted disturbance superimposed on a signal causing its components to be masked. 2.0.94 Input impedanceinput impedanceThe impedance between the input terminals of a meter.
2.0.95 Output impedanceoutput impedanceThe impedance between the output terminals of a meter.
2.0.96 Load impedanceload impedanceThe sum of the impedances of all devices and connecting wires connected to the output terminals of a meter. 357
3.0.1 Control
control
Process control terminology
A purposeful action on or within a system to achieve a specified goal. 3.0.2 Process controlprocesscontrol
The manipulation of variables that affect process conditions in order to achieve specified objectives. 3.0.3 Automatic controlautomaticcontrolControl without the need for direct or indirect human manipulation of terminal control elements. 3.0.4 Manual controlmanualcontrol
Control by direct or indirect human manipulation of terminal control elements. Note: In industrial processes, manual control is accomplished through standardized signals. 3.0.5 Monitoring
monitoring
Observing the operation of a system or part of a system to confirm correct operation and detect incorrect operation, which is accomplished by measuring one or more variables of the system and comparing the measured values with specified values. 3.0.6 Supervision
supervision
The control and monitoring operations of a system, including operations to ensure reliability and safety protection when necessary. 3.0.7 Loop
The combination of two or more instruments or control functions and the transmission of signals between them, thereby measuring and controlling process variables.
3.0.8 Control hierarchy controlhierarchy A graphical representation of the relationship between different levels of control (automation) arranged in increasing order of complexity of the master control system. 3.0.9 Control algorithm controlalgorithm A mathematical representation of the control action required to be performed. 3.0.10 Control system controlsystem
A system that achieves a predetermined state by precisely guiding or manipulating one or more variables. 3.0.11 Automatic control system automaticcontrol system A control system that operates without human intervention. It is divided into a master control system and a controlled system. 3.0.12 Master control system controllingsystem A system consisting of all the elements that control the controlled system. 358
Note: In feedback control, all elements in the feedback path are included. Controlled system
controlledsystem
A system that is controlled.
Real-time control system real-time controlsystem A computer control system that can respond quickly to inputs - rapid detection and rapid processing, and can provide output operation signals in a timely manner.
Control loop
controlloop
A combination of elements consisting of a comparison element, a corresponding forward path and a corresponding feedback path. Note: Sometimes a control loop can also include other loops. In this case, it is called a master loop, and the other loops it contains are called small loops, sub-loops, sub-loops, auxiliary loops or local loops. masterloop
5Master loop
A control loop that controls the main controlled variable. The output variable of its main controller is the reference variable of the slave controller.
Slave loop
A loop in which the slave controller controls the slave controlled variable. 3.0.18Actual valueactualvalue
The value of a variable at a given moment.
Expected valuedesiredvalue
The value of a variable required at a given moment under specified conditions. Setpointsetpoint
A signal representing the reference variable.
3.0.21Controlled variablecontrolledvariableThe output variable of the controlled system.
3.0.22 Manipulated variable
manipulated variable
The output variable of the master control system, which is also the input variable of the controlled system. 3.0.23 Reference variablereferencevariableThe input variable used by the master control system to set the expected value of the controlled variable. Note: 1. The reference variable can be set manually, automatically or by program. 2. The reference variable is usually expressed in the same units as the controlled variable. 3.0.24 Reference signalreference signalThe signal derived from the reference variable and compared with the feedback signal on the comparison element. 3.0.25Feedback signal3595 Monitoring
monitoring
Observing the operation of a system or part of a system to confirm correct operation and detect incorrect operation, which is accomplished by measuring one or more variables of the system and comparing the measured values with specified values. 3.0.6 Supervision
supervision
Control and monitoring operations of a system, including operations to ensure reliability and safety protection when necessary. 3.0.7 Loop
Combination of two or more instruments or control functions and the transmission of signals between them to measure and control process variables.
3.0.8 Control hierarchy control hierarchy A graphical representation of the relationship between different control (automation) levels arranged in increasing complexity of the main control system. 3.0.9 Control algorithm control algorithm A mathematical representation of the control action required to perform. 3.0.10 Control system control system
A system that achieves a predetermined state by accurately guiding or manipulating one or more variables. 3.0.11 Automatic control system automatic control system A control system that operates without human intervention. It is divided into a master control system and a controlled system. 3.0.12 Master control system controlling system A system composed of all the components that control the controlled system. 358
Note: In feedback control, all the components in the feedback path must be included. Controlled system
controlled system
The system that receives control.
Real-time control system real-time control system A computer control system that can respond quickly to inputs - quickly detect and quickly process, and can provide output operation signals in a timely manner.
Control loop
controlloop
A combination of components consisting of a comparison element, a corresponding forward path and a corresponding feedback path. Note: Sometimes a control loop can also include other loops. In this case, it is called a master loop, and the other loops it contains are called small loops, sub-loops, sub-loops, auxiliary loops or local loops. masterloop
5Master loop
A control loop that controls the main controlled variable. The output variable of its master controller is the reference variable of the sub-controller.
slaveloop
A loop in which the slave controller controls the slave controlled variable. 3.0.18actualvalueactualvalue
The value of the variable at a given moment.
desiredvaluedesiredvalue
The value of the variable required at a given moment under specified conditions. setpointsetpoint
The signal representing the reference variable.
3.0.21controlledvariableThe output variable of the controlled system.
3.0.22manipulatedvariable
manipulatedvariable
The output variable of the master control system, and also the input variable of the controlled system. 3.0.23referencevariableThe input variable for the master control system to set the desired value of the controlled variable. Note: 1.The reference variable can be set manually, automatically or by program. 2.The reference variable is usually expressed in the same unit as the controlled variable. 3.0.24 Reference signal A signal derived from a reference variable and compared with the feedback signal on a comparison element. 3.0.25 Feedback signal5 Monitoring
monitoring
Observing the operation of a system or part of a system to confirm correct operation and detect incorrect operation, which is accomplished by measuring one or more variables of the system and comparing the measured values with specified values. 3.0.6 Supervision
supervision
Control and monitoring operations of a system, including operations to ensure reliability and safety protection when necessary. 3.0.7 Loop
Combination of two or more instruments or control functions and the transmission of signals between them to measure and control process variables.
3.0.8 Control hierarchy control hierarchy A graphical representation of the relationship between different control (automation) levels arranged in increasing complexity of the main control system. 3.0.9 Control algorithm control algorithm A mathematical representation of the control action required to perform. 3.0.10 Control system control system
A system that achieves a predetermined state by precisely guiding or manipulating one or more variables. 3.0.11 Automatic control system automatic control system A control system that operates without human intervention. It is divided into a master control system and a controlled system. 3.0.12 Master control system controlling system A system composed of all the components that control the controlled system. 358
Note: In feedback control, all the components in the feedback path must be included. Controlled system
controlled system
The system that receives control.
Real-time control system real-time control system A computer control system that can respond quickly to inputs - quickly detect and quickly process, and can provide output operation signals in a timely manner.
Control loop
controlloop
A combination of components consisting of a comparison element, a corresponding forward path and a corresponding feedback path. Note: Sometimes a control loop can also include other loops. In this case, it is called a master loop, and the other loops it contains are called small loops, sub-loops, sub-loops, auxiliary loops or local loops. masterloop
5Master loop
A control loop that controls the main controlled variable. The output variable of its master controller is the reference variable of the sub-controller.
slaveloop
A loop in which the slave controller controls the slave controlled variable. 3.0.18actualvalueactualvalue
The value of the variable at a given moment.
desiredvaluedesiredvalue
The value of the variable required at a given moment under specified conditions. setpointsetpoint
The signal representing the reference variable.
3.0.21controlledvariableThe output variable of the controlled system.
3.0.22manipulatedvariable
manipulatedvariable
The output variable of the master control system, and also the input variable of the controlled system. 3.0.23referencevariableThe input variable for the master control system to set the desired value of the controlled variable. Note: 1.The reference variable can be set manually, automatically or by program. 2.The reference variable is usually expressed in the same unit as the controlled variable. 3.0.24 Reference signal A signal derived from a reference variable and compared with the feedback signal on a comparison element. 3.0.25 Feedback signal
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