The identification of the information o ject – the sig al name – is therefore the most b sic is ue in the con tru tion of the sig al desig ation se Clau e 5.. For the purp se of identify
General principles on signal transfer and signal naming 1 1
Signals are representations of information objects that are exchanged among objects Normally a signal has one source and one or many destinations (see Figure 2)
Source Signal Destination Source Signal Destination
Signal with parallel transmission paths
Figure 2 – Signal with source and destination(s)
The transmission of a signal from source to destination may require one or many signal carrying media, see Figure 3, which in turn requires signal connection media in order to operate
If a change of a signal carrying medium to another or a change of a signal connection medium to another is required, transformations can be necessary
At such transformations, the represented information object shall remain unchanged, see Figure 3
Signal connection medium 1 : e.g copper wire Signal connection medium 3: e.g optical fibre
Signal carrying medium 1 : e.g current Signal carrying medium 3: e.g light
Signal carrying medium 2: e.g radio frequency
* without change of information object
Figure 3 – Information object transmitted via different signal carrying and connection media
If the information object of a signal is intentionally processed, for example the information object being delayed or being subject to a logic condition, a new signal shall be created, see Figure 4
Processing Signal 2 e.g “tempErature” e.g “switch off”
Figure 4 – Different signals caused by processing/logical linking
If the information object with respect to the intended information exchange is modified, a different signal name shall be applied.
The identification of the information object – the signal name – is therefore the most basic issue in the construction of the signal designation (see Clause 5).
Signal classification 1 2
The signal may be classified according to different characteristics The signal classification provided in this part of IEC 61 1 75 is based on the purpose of the signal
Two groups of signals exist with respect to their treatment in designations:
The classification of these two groups is determined by the direction of information flow concerning the objects involved When a signal is transmitted among multiple objects, it is essential to designate one object as the primary entity.
The "main object" refers to an entity primarily linked to the main process, distinguishing it from controlling or monitoring processes, which are associated with auxiliary functions.
A switch in a control panel sends a signal to close a circuit breaker in the main process The circuit breaker acts as the primary object, with the signal serving as a control mechanism Additionally, the circuit breaker indicates its closed position by providing a signal to the control panel, reinforcing its role as the main object while this signal functions as a report.
Figure 5 – Relation between controlling and reporting signals The two groups are further split into signal classes:
• Reporting signal group contains the following classes: alarm signal, event signal, indication signal, measuring signal (including power supply);
• Controlling signal group contains the following classes: command signal, setting value signal
Table 1 provides these signal classes together with associated letter codes to be used as part of the signal name.
Signal name domain 1 3
The signal name domain establishes a specific area where a signal name remains unambiguous For details on identifying signal name domains, refer to section 5.1.2 This allows for the reuse of signal names across different, clearly defined signal name domains Various methods can be employed to define these domains.
• Both, source and destination of the signal are constituents of the object serving as domain (see Figure 6 a) This shall be applicable for all signals if such a common object exists
• The object that constitutes or contains the destination of a signal is chosen as domain (see Figure 6 b) This is mainly applicable for controlling signals
• The object that constitutes or contains the source of a signal is chosen as domain (see Figure 6 c) This is mainly applicable for reporting signals
Figure 6 – Object serving as signal name domain
Structure of the signal designation 1 4
A signal designation must clearly identify a signal across all connections within a signal connection network, remaining independent of any specific connection or carrier medium The designation is composed of several key components.
• object designation of the signal name domain (see 5.1 2);
• prefix for signal name (see 5.1 3);
• signal name (further substructure, see 5.1 4)
For the purpose of identifying a specific signal connection in a signal connection network or for providing additional information related to that connection, the signal designation may be supplemented by
The structure of a signal designation shall be as shown in Figure 7
Detailed rules on presentation of signal designations in documents are provided in IEC 61 082-1
Prefix sign indicating the signal name
Designation of the object which is the domain of the signal designation
Object designation :Signal connection id (Sign Conn char.)
Signal designation Signal designation with signal connection information
Character indicating signal connection information
Figure 7 – Signal designation and signal connection identification
The object designation serves as a unique identifier within the signal name domain, ensuring that the signal name is clear and valid It must be made unambiguous within the specific or intended system context.
The selection of the object for the signal name domain should be determined by either recognizing the overall object that includes both the source and destination or by naming a primary object within the signal connection network as outlined in section 4.2 Consequently, the signal name domain is defined by the designation of the overall object or the specific controlled or reporting object.
A reference designation in accordance with IEC 81 346-1 is considered as an unambiguous designation of an object
If a reference designation in accordance with IEC 81 346-1 is used, it shall be applied as object designation
The signal name shall be preceded by a prefix sign, namely the character “;” (semicolon)
In presentations, the prefix sign can be omitted when the context is clear, such as in a signal list where the column header indicates the meaning However, the prefix sign must be included when a signal name is presented alongside a preceding object designation.
The signal name shall identify the information object by providing short but significant information on that information object
It is composed of the following elements:
• signal class (optional); consisting of a code (see Table 1 );
• short name (optional), representing the related source or destination object in the form of a short or abbreviated textual description (see Table 2);
• basic signal name (mandatory), consisting of a code representing the specific function of the signal with respect to the object (see Table 3)
Considering that the signal name as a whole is an identifier, it shall be considered as a language independent string This implies that it shall not be translated
Language-dependent information related to the signal, for example text presented on a display, may be provided as separate information but not shown within the signal name
The structure of a signal name shall be in the form shown in Figure 8, to be read from left to right
In presentations, signal names can be distinguished by a single space or by using the underscore character "_" For better readability, it is advisable to use the underscore.
NOTE In a specific system, for example a communication system, the signal name can be presented using the different parameters of the information object
If an indication of the signal class in the signal name is required, the signal class code in accordance with Table 1 shall be applied short name
Signal name signal class code
Code of signal class (optional); see Table 1 Separator sign (optional)
Short designation of the reporting or controlled object (optional); proposals see Table 2
Code for specific function of the signal (mandatory); proposals see Table 3
Table 1 – Letter codes for signal classes
Signal class code Signal class Examples
The letter code I has been replaced by the letter code D, as the use of letter codes I and O is generally deprecated In accordance with IEC 61175:2005, the letter code I is now indicated as an alternative letter code for the signal class "Indication signal."
Sub-classification of the classes may be indicated by adding a number (1 ,… , 9) Additional classification outside Table 1 shall be explained by accompanying documentation
Signal classes denominated as “User’s choice class” are provided for specific applications which, if applied, shall be be defined and documented by the user
The short name serves to give a general indication of the type of object or phenomenon being observed, whether it is controlled or reported Users have the flexibility to select a short name that best meets their specific needs, as illustrated in Table 2.
Table 2 – Examples of short names
Short names may be supplemented, for example with counting numbers, for differentiation
The identification of the signal name domain, i.e the reference designation (see 5.1 2), shall not be repeated as part of the signal name
The basic signal name is a concise code that conveys the function of the signal related to the controlled or reported object, phenomenon, status, or quantity Users have the flexibility to choose the basic signal name according to their specific needs, as illustrated in Table 3.
Table 3 – Examples of basic signal names
In technical fields, mnemonics are created for particular purposes and are advised to be utilized as concise names or fundamental signal identifiers in documents tailored for specific applications within those areas.
For indication of proportional relation, the less-than sign () may be added to a relevant code in Table 3 (see example below)
EXAMPLE Max< indicates an operation level lower than maximum level Max indicates an operation level identical with maximum level Max> indicates an operation level higher than maximum level
In case of measuring signals or power supply, specific codes for basic signal names are often applied More information is provided in 5.3.1 4 and 5.3.1 5
When a signal class is clearly specified and a verb is included in the basic signal name, the verb must be in the imperative form for both reporting and controlling signals, such as in the examples C_CB_close and D_CB_close.
The meaning of the letter codes in short name and basic signal name should be described in the document where it is used or in supporting documentation
The signal connection identifier is an identification of a part of a signal connection network This identifier can be added as optional information
To identify a signal connection within a network from the source to the destination, it is essential to include a signal connection identifier in the signal designation, which should be preceded by a colon (":").
There are some cases when signal connection identifiers should be added to the signal designation These cases occur when a signal is being transferred:
• from one system to another;
• from one component to another;
• from one signal connection medium to another;
• from a source to different destinations (a split of the signal connection network)
If there is only one section in the transmission chain, it is not required to explicitly use a signal connection identifier
The signal connection identifier in turn may be supplemented by signal connection characteristics, see 5.1 6 If signal connection characteristics are provided, the separator sign
“:” shall be presented also in the case when no section of the signal connection identifier is explicitly indicated (meaning the signal designation is related to one signal connection only)
The signal connection characteristics section offers essential details about the attributes of a signal connection When necessary, these characteristics should be indicated in parentheses “(… )” after the signal connection identifier or a colon “:” if there is only one signal connection Refer to Figure 1 3 and Figure 1 4 for additional context.
The signal connection characteristics may include:
• data related to the transmission of the signal (e.g voltage level);
• alternatively name or other information related to packaging of information objects for transferring;
• other system information, for example protocol related parameters.
Recommended characters 1 9
Signal designations should be composed from standard character sets
To maintain compatibility with computer processing, character sets should be restricted to those characters in ISO/IEC 646:1 991 , Table 4 – Basic code table, excluding control characters and national replacement characters
If the computer and communication systems used are restricted to those that can process 8- bit single byte coded graphic character sets, ISO 8859-1 is recommended for supplementary characters
The recommended characters include the following:
• Upper case Latin characters A through Z;
• Lower case Latin characters a through z;
• spacing characters: underscore (_) or space;
• signal connection identifier separator: colon (:);
• indicator of signal connection characteristics:());
• special characters: EXCLAMATION MARK (!); QUOTATION MARK ("); PERCENT SIGN (%); AMPERSAND (&); APOSTROPHE ('); ASTERISK (*); COMMA (,); FULL STOP (.); SOLIDUS (/); LESS-THAN SIGN (); HYPHEN-MINUS (-); PLUS SIGN (+); QUESTION MARK (?).
Forming signal designations
Reporting signals
A reporting signal conveys information from a source to one or multiple receivers To identify the signal name domain for a reporting signal, it is recommended to use the reference designation of the object where the reporting object is located.
Figure 9 illustrates various scenarios: a) multiple reporting-type signals originating from a single source and directed to several destinations; b) several signal connections transmitting the same signal to two destinations, where the signal domain is a function object encompassing both the reporting object and the destinations; c) a similar case to b), but with the signal domain specifically referencing the reporting object.
Object designation ; Signal name: 1 Reporting object
: represents signal transformation without changing signal meaning
: represents signal transformation without changing signal meaning
Figure 9 – Examples of reporting type of signals
The indication signal conveys crucial information about the operational state of a source object, which may exist in one or multiple defined positions, such as on, off, or intermediate Examples of these indication signals are illustrated in Figure 1.
Object designation ; D_E-Sw_Open Object designation ; D_E-Sw_Close Object designation ; L_DC_1 1 0 V
NOTE The figure shows two indication signals (class D) and one power supply (class L)
Figure 1 0 – Example of an indication signal
5.3.1 3 Alarm and event signals (A and E)
The information object represented by an event signal provides information on a specific event Figure 1 1 shows a connection of an event signal to a registration system
NOTE Typically, these types of signals are created by the signal source in the case of a changed status, for example in process supervisory device
The information object represented by an alarm signal provides information on a specific abnormal situation or event that requires specific action
Event list Pump No 1 started
Figure 1 1 – Example of an event signal
The classification of signals into indication, alarm, and event categories is not always straightforward and should be determined by the user based on the operational information needs of the system or plant If the signal's purpose is unclear or differentiation is unnecessary, class D should be utilized.
The information object represented by a measuring signal provides information on the value of a measured quantity The measured quantity can be transmitted via analogue or digital means
When measuring signals, the basic signal name must accurately reflect the quantity being measured If the signal name is coded, the first character should follow the letter codes outlined in Table A.1, while the second character should adhere to the codes specified in either Table A.2 or Table A.3, as illustrated in Figures 1.2 and 1.3.
M = measuring signal, CT2 = current transformer 2, I1 = current core 1 , L3 = phase L3
Figure 1 2 – Example of measuring signals
The measuring device generates a signal that can be transmitted through various carrier media along its signal connection network Despite the different media used, the signal retains the same name since it represents the same information object If necessary, the distinct carrier media should be identified as separate signal connections.
Figure 1 3 – Example of an analogue measuring signal transmitted in different forms
Specific attributes associated with the carrier medium, such as time stamps for digital messages of analog values, can be enhanced through signal connection characteristics or provided as separate but related information.
; M_VT1 _UL1 :2(1 0 mA) ; M_VT1 _UL1 :1 (1 1 0 V)
Communication message Object designation ; M_VT1 _UL1 :3(Time)
Figure 1 4 – Example of signal connection characteristics related to measuring signals
Power supply sources are usually of the electrical kind but may also include other supply sources like compressed air in pneumatic circuits or light-supply in light wave circuits
Power supplies, while not signals themselves, can be labeled using similar principles as those applied to signals These designations are intended for simplification and will henceforth be referred to as signal designations, treating them as reporting signals.
Power supply connections must be labeled based on the physical quantity they convey, which can include a numerical value with a unit of measure or a widely recognized abbreviation indicating a nominal value These labels may also suggest tolerances or other relevant properties.
• a functional earth connection may be named 0 V or FE;
• a protective earth connection may be named PE;
• a TTL supply voltage connection may be named L+ or L+5 or +5 V or V+ or VC;
• a power main connection may be named L1 or 50 Hz 230 V L1 ;
• a power connection to a motor in a variable speed drive with variable frequency and variable voltage may be named L1 or VFL1
Signal names for electric supply circuits must be based on the letter symbols specified in IEC 60747 or IEC 60445, where applicable For ease of reference, conductor markings from IEC 60445 are provided in Table A.3, with an illustrative example depicted in Figure 1.
The signals originate from the power supply unit DC5, as indicated by their names, which suggest they are derived from either the positive or negative direct current (d.c.) supply.
Figure 1 5 – Example of power supply designation
Controlling signals
A controlling signal conveys information from multiple sources to a designated controlled object, aiming to initiate an operation or activity To identify the signal name domain for a controlling signal, it is preferable to use the reference designation of the object where the controlled object is located.
• Setting value signal ;S_Pump_Flow where C and S are signal classes; Pump is the short name and Start and Flow are basic signal names
Figure 1.6 illustrates two scenarios: a) multiple controlling signals from various sources influencing a single destination object, and b) a single controlling signal that integrates inputs from several sources to affect the same destination object.
Source 1 Object designation ; Signal name: 1
=MA1 ;C_Mot_Stop:1 Controlled object
Local control =MA1 ;C_Mot_Stop:2
Figure 1 6 – Examples of typical controlling type of signals
A command signal serves as an information object that activates operations, such as starting or stopping activities, within a controlled process For instance, Figure 1 illustrates a command signal designed to regulate a pumping system.
Figure 1 7 – Example of a command signal
The information object represented by a setting value signal provides information used to modify a specific parameter related to the controlled process Figure 1 8 shows a setting signal intended for controlling a regulator
Figure 1 8 – Example of a signal for setting value
6 Identification of signals in the signal connection network
General
Signals, whether reporting or controlling, are transmitted from their source to destination through one or multiple signal connections At the interface between different sections of a signal connection network, the signal is typically transformed for transmission through an alternative signal connection medium or a different signal-carrying medium.
The fundamental information of a signal is defined by its name, which remains consistent regardless of the transmission medium or physical form As long as the information content remains unchanged, the signal name will also stay the same within a signal connection network.
Figure 1 9 and Figure 20 show two different examples of how signal connection networks can be identified
Each signal connection in the network is uniquely identified by a signal designation and a connection identifier This allows the signal from the source to be easily recognized throughout the network and at its destination by its signal name alone.
Figure 1 9 – Signal connection identifiers in a single connection network
Figure 20 – Example of signal connection identifiers in a current measuring circuit
Pre-defined signal names
In some cases internal signal designations are provided by the manufacturer of a component
In a signal connection network, internal signal designations can serve as identifiers for related signal connections when referenced in a document.
To v ol ta ge tra ns fo rm er
Circuit Breaker No 1 Indication, Close
Figure 21 – Signal connection identifiers by internal signal name
Figure 21 illustrates a signal connection network within the connecting chain of a PLC (Programmable Logic Controller), highlighting the input and output terminals The signal connection identifiers displayed in the PLC represent the signal names designated by the program's designer, with S1 indicating the input signal name and Out1 representing the output signal name.
Grouping of signals
General
For different reasons signals may be arranged in groups With regards to signal naming two kinds of signal grouping can be identified (see 6.3.2 and 6.3.3).
Packaging of signals in signal carrying medium
The purpose of packaging signals within a specific medium is to enhance communication in a signal connection network Upon transmission, the signal package is designed to be unpacked into individual signals that contain the same information objects used during packaging Each information object must be identified and assigned its own signal designation within the package Furthermore, the signal package requires an identifier, which may include a signal designation along with a common name for the package.
Grouping of signals for presentation
Signals can be combined for unified presentation, resulting in a new signal that encapsulates the information from the grouped signals However, this new signal does not allow for the identification of the individual signals within it Additionally, the new signal must have its own unique designation.
7 Signal identification in interfaces for data exchange
General
In the transfer of information from source to receiver, signals may traverse interfaces between systems or components, where terminal devices facilitate the connection While the overall signal designation remains unchanged, the identifiers for the signal connections will differ Components managing signals often adhere to predefined internal naming conventions, which may not align with standardized protocols Consequently, the internal naming of information objects in software may differ from established signal naming conventions in IEC 61175 It is the customer's responsibility to determine the acceptability of these naming principles, and if accepted, additional requirements for establishing signal interfaces may arise.
Interface between electric circuit and programmable devices, I/O
Programmable devices, such as PLCs, utilize input/output (I/O) modules to facilitate communication between internal logic programs and external electrical signals It is essential for the I/O module to accurately represent both internal and external signal names, with a strong recommendation for internal designations to align closely with external ones, even if full identity is not achievable due to software naming constraints To ensure optimal similarity, a consistent information model should be applied across all designations of information objects, ensuring that the meanings of internal and external signal names remain consistent.
For further information about designation of signals in binary logic representation, see Annex B.
Interface for logic communication
Most industrial communication protocols rely on the transmission of data objects, which are packages of signals rather than mere signals themselves This approach enhances the information content of a signal by including additional related information necessary for effective transmission and comprehension by the receiver.
For further information see Annex E
Representation vs presentation of a signal designation
The representation of a signal designation describes how the designation shall be constructed in order to allow computer software to decompose it into constituent parts
A signal designation can be conveyed as a continuous string, requiring the inclusion of all defined prefix signs that separate its various components.
A signal designation can also be conveyed as a collection of components, where each component represents a specific and recognized data element type In this scenario, the defined prefix signs may be excluded.
NOTE Data element types usually are defined according to I EC 61 360-1 See also Annex F
The presentation of a signal designation shall be such that a human being shall be able to recognize the different parts
If the designation is communicated as an unbroken string this can easily be done by means of the included prefix signs
If the designation is communicated in parts the appropriate prefix sign needs to be added at presentation.
Human machine interface, HMI
In a human-machine interface (HMI), signals can be represented in various forms, such as graphical symbols, annunciator panels, event lists, or bar graphs When presented textually, signal identification must be clear and easily understood by users According to IEC 61175, signal names often use abbreviations that are not suitable for display on screens Thus, it is essential to convert signal presentations in HMIs into more user-friendly text or standardized symbols to enhance comprehension.
Typical for the presentation of the signal (information object) in an HMI is that the information in textual form is divided into blocks (columns), for example:
• the object name and basic signal name is shown in more describing textual form;
• the classification code or signal connection identifier need not be used in the presentation;
• the signals are arranged in groups with respect to the related objects, with a common object designation (reference designation) as a rubric for the group;
• signal connection characteristics are shown as parameters for the presentation of a signal
This part of IEC 61 1 75 does not make any further requirements or recommendations for the representation of signals in human machine interfaces, but see also IEC 60447, IEC 6041 7 and IEC 62744.
Presentation in documentation
The primary aim of IEC 61 1 75 is to establish a standardized signal designation for use in diagrams and technical documentation It is advisable to label objects in diagrams with reference designations following IEC 81 346-1 and IEC 81 346-2 to ensure consistency in object designations within signal designations.
For the presentation of signal designations in documentation, IEC 61 082-1 shall apply
Simplified presentation methods are essential for effectively conveying signal designations A reference designation, applicable to all signals, is displayed once within a surrounding boundary frame and is omitted from individual signal designations inside that frame This reference designation is marked with a semicolon (;) to indicate its connection to the signal designation When interpreting a signal designation, one begins with the reference designation, which is then combined with the signal names along the connecting lines For instance, in the example provided, all signals share the designation =W1 E1 Q1 ;D_CB1 _Close, while various signal connections within the network are further identified by numbers.
Bay 1 (Signal name domain) Subsystem 1 1 0 kV
NOTE The arrows indicate the concatenation of the common part of the signal designations (outside) with the individual parts of the designation (inside an object)
Figure 22 – Use of concatenated reference designations in a plant
Presentation of metadata for signals
A signal serves as an information object that can be characterized by its metadata This metadata is often reflected in the signal's designation, while additional relevant metadata can further describe the signal These various metadata elements can be compiled into a comprehensive metadata object.
For exchange of metadata of a signal, the metadata object may be transferred in a standardized format, for example extensible markup language (XML)
Figure 23 illustrates a signal displayed in both a single line format and a tabular format, highlighting its properties along with their corresponding values The unit of measurement, Volt, is clearly presented as text, which is the preferred notation for human readability.
The right side of Figure 23 illustrates an example of signal designation using XML notation, which is designed for information processing It is advisable to use clearly defined codes (keys) for units to facilitate automated conversion or localization of units within the same physical quantity, such as converting meters to inches or feet, in accordance with ISO 80000-9 When encoding units, the codes specified in IEC 62720 should be utilized.
Figure 23 – Metadata representing a signal and corresponding XML file Further examples of the presentation of metadata for signals are given in Annex C
Annex A (normative) Letter codes for use in signal names
Letter codes for variables
The letter codes in Table A.1 are primarily based on International Standard 80000 and are used to identify the variables measured by sensors These codes serve as the initial character in the coded basic signal name for a measuring signal, indicating the specific variable represented by the signal.
Table A.1 – Letter codes for variables based on International Standard 80000,
Letter code Name of variable
(Quantity) Reference to International Standard 80000
K Time (point in time, clock)
Time (duration of time) 5-1 , letter symbol “ θ ”
3-8 1 , letter symbol “ v ” 3-4, letter symbol “ V ” 4-24, letter symbol “ ν ”
In accordance with International Standard 80000, letter codes are represented using upper case Latin characters Additionally, quantities are denoted with either upper or lower case characters from the Latin or Greek alphabet, formatted in italic font It is important to note that variable names presented in italic font are not sourced from International Standard 80000.
If additional variables representing physical quantities are required, it is recommended to refer to the quantities as listed in International Standard 80000 or IEC 60027.
Letter codes used as modifiers
The letter codes in Table A.2, as defined by ISO 14617-6, are used in instrument symbols to denote measurements of quantities other than the absolute level of the specified variable These codes also serve as the second character in the coded names for measuring transducer output signals or similar signals.
The signal connection identifier signifies a quantity distinct from the absolute level of the variable denoted by the initial character of the coded name This code will serve as the identifier for the signal connection.
Table A.2 – Letter codes used as modifiers
Letter code second letter Modifier
Identification of certain designated conductors
According to IEC 60445, the letter codes listed in Table A.3 are designated for identifying specific conductors and must be incorporated into the signal designation for signals associated with those conductors.
Table A.3 – Identification of certain designated conductors
L1 Phase 1 for a.c supply L2 Phase 2 for a.c supply L3 Phase 3 for a.c supply
L + Positive for d.c supply L− Negative for d.c supply
PEN Protective conductor (see IEC 60050-1 95:1 998, 1 95-02-1 2) PEM Protective conductor (see IEC 60050-1 95:1 998, 1 95-02-1 3) PEL Protective conductor (see IEC 60050-1 95:1 998, 1 95-02-1 4)
FB Functional equipotential bonding conductor
Annex B (informative) Binary logic representation
General
A signal connection identifier can convey information using binary logic, where the signal exists in only two distinct states These states are represented by two non-overlapping ranges of physical values.
In binary signal representation, a basic signal name often serves as an abbreviation for a statement or expression that can be evaluated as either true or false (1 or 0) For instance, the name ALARM represents the statement "alarm is active." The truth value derived from evaluating this statement is referred to as the logic state, or "the signal state," of the signal connection.
The true value of the statement represented by the basic signal name corresponds to the
The state of a signal connection is defined by its basic signal name, where a false value corresponds to the 0-state For instance, the signal name ALARM indicates that the alarm is active (true) when in the 1-state and inactive (false) when in the 0-state.
NOTE 1 The signal state being true always corresponds to the external logic state being 1
NOTE 2 The signal state being false always corresponds to the external logic state being 0
Figure B.1 – Signal states of binary signals
Negated signal
A signal connection identifier can indicate the negated version of a preceding signal, which is applicable in binary signal representation In certain scenarios, an action is required when a specific condition is false An example of a negated signal is illustrated in Figure B.2.
1 ALARM alarm true =1 1 1 no alarm false=0 0 0
2 ALARM alarm true =1 1 0 no alarm false=0 0 1
3 ALARM alarm false=0 0 0 no alarm true =1 1 1
4 ALARM alarm false=0 0 1 no alarm true =1 1 0
Relationship defined by presence or absence of negation symbol
System Signal state External Internal
No Input (or output) condition (truth-value) logic state logic state
1 ALARM alarm true =1 1 1 no alarm false=0 0 0
2 ALARM alarm true =1 1 0 no alarm false=0 0 1
3 ALARM alarm false=0 0 0 no alarm true =1 1 1
4 ALARM alarm false=0 0 1 no alarm true =1 1 0
Relationship defined by presence or absence of negation symbol
System Signal state External Internal
No Input (or output) condition (truth-value) logic state logic state
1 ALARM alarm true =1 1 1 no alarm false=0 0 0
2 ALARM alarm true =1 1 0 no alarm false=0 0 1
3 ALARM alarm false=0 0 0 no alarm true =1 1 1
4 ALARM alarm false=0 0 1 no alarm true =1 1 0
Relationship defined by presence or absence of negation symbol System Signal state External Internal
No Input (or output) condition (truth-value) logic state logic state
The preferred methods of indicating negation in a name are as follows
• Precede the appropriate portion of the basic signal name by the mathematical sign for logic negation; for example ơRUN
NOTE 1 The “ơ” sign is available in the ISO/IEC 8859-1 , 8-bit single graphic character set
NOTE 2 The character NOT SIGN is not included in the character set specified in ISO/IEC 646 In this case the tilde (~) can substitute the “ơ” sign on computer systems
• Place a negation bar ( ) over the portion of the name representing the expression to be negated; for example RUN
This method is not advisable for text or graphical documents created by programs that cannot properly attach the negation bar to the text, ensuring it moves accordingly.
NOTE 3 This method is typically used in expressions with Boolean algebra
• Use another notation explained in the document or in supporting documentation
Figure B.2 – Example of a negated signal
Annex C (informative)Examples for signal lists including signal connection identifiers
Presentation of voltage measurement signal, class M
Clause C.1 and Clause C.2 illustrate how signals and their connection identifiers can be displayed in a list format However, this presentation style is rarely utilized, as signal connection identifiers are usually found only in the associated documents.
This example shows the signal designation with a signal connection identifier 3 in a voltage- measuring signal In
Figure C.1 , the complete signal connection network, including five signal connections, is explained The signal connection identifiers are shown as examples based on this part of IEC 61 1 75
• signal designation, which is the same for all signal connections;
• signal connection 1 , which is the measured value in the process;
• signal connections 2 to 4, which represent paths in the signal connection network;
• signal connection 5, which is the representation of the signal in the signal destination
Reference designation =PP1 E1 Q1 Signal name domain, defined as:
Power Plant 1 ; 1 1 0 kV system; Bay1
Signal class code M Measuring signal
Short name VT1 Voltage transformer 1
Basic signal name U1 L1 Voltage; Group 1 , Phase L1
SIGN AL CONNECTION 1 : Primary system at Bay 1
Signal connection characteristics (1 1 0 kV) Nominal primary voltage
Range Nominal 1 1 0/√3 Information used in documents
SIGN AL CONNECTION 2: Output of voltage transformer
Signal connection characteristics (1 00 V) Nominal secondary voltage
Range Nominal 1 00/√3 Information used in documents
SIGN AL CONNECTION 3: Voltage converted to current after transducer Signal connection characteristics (1 0 mA) Analogue electrical value
Range Nominal 0… 1 … 1 0 Information used in documents
Corresponds to 0 % to 64 % of measured value
Corresponds to 64 % to 100 % of measured value
SIGN AL CONNECTION 4: Communication in telecontrol system
Signal connection characteristics (digital) Digitized value
Range Nominal 0… 32768 Information used in documents
Max value 32768 Maximum signal value
Measured 25 % Nominal value corresponds to 25 % of signal value
SIGN AL CONNECTION 5: Presentation in telecontrol system
Signal connection characteristics (HMI) Calculated voltage in computer system
Range Nominal 32768 = 528 Value 32768 correspond to 528 kV
Max value 528 × 25 % = 1 32 Maximum value for presentation
Figure C.1 – Voltage measurement, reporting signal class M
Presentation of a controlling signal, class C
EXAMPLE =PP1 E1 Q1 QB1 ;C_Disc_Open:3 (48V)
This example illustrates the signal designation and connections for a command signal, as detailed in Figure C.2 The figure explains all components of the signal designation along with their connection identifiers, which are provided as examples based on IEC 61175 The list encompasses various signal connection identifiers.
• signal designation, which is the same for all signal connections;
• signal connection 1 , which is the realization of the command in the actuator;
• signal connection 2, which represents the local operation; and
• signal connection 3, which is the plant level operator control switch
Reference designation =PP1 E1 Q1 QB1 Signal name domain, defined as:
Short name Disc Disconnector switch
Basic signal name Open Open
SIGN AL CONNECTION 1 : Actuator in the disconnector switch Signal connection characteristics (1 1 0 V) Electric signal value 1 1 0 V
Nominal level 1 1 0 Information used in documents
SIGN AL CONNECTION 2: Bay level operator switch
Signal connection characteristics (1 1 0 V) Local command, value 1 1 0 V
Nominal level 1 1 0 Information used in documents
SIGN AL CONNECTION 3: Station level operator switch
Signal connection characteristics (48 V) Remote command, value 48 V
Nominal level 48 Information used in documents
Figure C.2 – Command signal for a disconnector, controlling signal class C
Annex D (informative) Generic communication needs in a process
Process model
Figure D.1 illustrates a generic process where information objects are created, transmitted, and utilized at various stages This description is grounded in the object classification model outlined in IEC 81 346-2:2009, as depicted in Figure A.1 The connections between the objects signify standard communication media.
The IEC 81 346-2 model illustrates the relationships between various object classes Additionally, Figure D.1 enhances this model by incorporating communication facilities among the objects and introducing human system interfaces, which include engineering tools and their associated documented reports.
Figure D.1 – Communication model based on IEC 81 346-2
Signal connection and signal presentation media
General
For communication (transferring of signal objects) among the process objects in the model, different kinds of signal connection media are used The signal connection media,
IEC 61 1 75-1 :201 5 © IEC 201 5 – 41 – represented by different types of lines in Figure D.1 , are briefly described in D.2 Additionally, the different types of signal presentation media shown in the Figure D.1 are briefly described.
Wiring
Electric wiring is essential for connecting objects involved in the main process and for linking power supply from resource supply sources In an electrical system, a single wire or core within a cable usually conveys a specific piece of information The logical representation of signal transfer is illustrated by a line or a group of lines in a circuit diagram.
Internal bus
Shown as Internal bus (black line)
Figure D.1 illustrates a controlling device, referred to as an Intelligent Electronic Device (IED) in IEC 61850 standards This device comprises multiple functional units for data processing, which can be categorized as various object classes or tailored for specific classes Typically, the device communicates internally through a communication bus, where all incoming information via electric wires is digitized in the I/O modules and subsequently distributed as data The definition and identification of the data transmitted over the bus are governed by proprietary interface descriptions that are not meant for external access.
External bus
Shown as External bus (red line)
The controlling device can exchange a preset of internally managed data with other devices, such as the HMI device, through an "External bus." This intelligent communication bus utilizes structured identification of data objects and adheres to standardized definitions, such as IEC 61850 Data is stored on a server, allowing multiple clients to access it To ensure clarity in the data exchanged between the client and server, a common data model of the supervised and controlled process must be established within the system.
Information objects transmitted over the external bus can be organized into packages for efficient communication Upon reaching the receiver, these packages are unpacked and displayed as separate information objects, each identified by a unique signal designation.
Presentation in the human interface, HMI
The presentation of human perception in the supervised process can effectively utilize images, symbols, and text It is crucial that the identification of objects, including signal objects, aligns with the terminology used in the documentation.
Other human presentation
D.2.6.1 Printed reports from the HMI device
A standard HMI presentation often features reports on alarms and recognized events from the monitored process For documentation, these reports can be either printed or saved as electronic files.
The supervised process and supervising system are usually documented through various types of documents, including circuit diagrams for electrical systems, system function diagrams, program charts for control devices, and interface descriptions for communication.
Applicability of signal designations
In electrical system
The electrical system is represented through various documents, including circuit diagrams, connection diagrams, and connection tables IEC 61175 is designed to be fully applicable to these types of documentation.
In control devices (with internal numerical communication)
The designation of data transmitted through electronic devices largely relies on the software programs utilized As a result, the comprehensive guidelines of IEC 61175 may not fully apply to these devices and their documentation Internal signal naming serves as a method for identifying internal signal connections.
For an effective internal software system, the information model representing the supervised process must align with the overall process description in terms of information structuring This includes utilizing a consistent reference designation system throughout.
• The interface of signals shall be described in, for example, an I/O list, in which the relation between internal and external signal designations can be recognized
• Internal signal names (variable names, etc.) shall as far as possible correspond to the basic signal name used for the signal objects in other process descriptions, e.g in a circuit diagram.
In external communication
The designation of data transmitted over an external communication bus is influenced by the communication protocol employed, much like electronic devices Therefore, the relevance of IEC 61175 aligns with this principle.
Different types of protocols are utilized for coding and decoding information transmitted from a sender to a receiver The OSI model [ISO/IEC 7498] effectively describes the capabilities of these protocols in relation to information objects Protocols operating at higher levels of the OSI model can identify and design information objects in alignment with IEC 61175 standards.
In the HMI
The presentation of information in a Human-Machine Interface (HMI) for operators is not covered by IEC 61175 standards It is essential to tailor this presentation to best suit the information receiver It is recommended that object descriptions and designations align with those in the plant's documented description Additionally, if basic signal names are utilized in the HMI, they should match the basic signal names found in the documentation, assuming the same language is employed in both instances.
Annex E (informative) Restructuring of information for communication purposes
General
Most industrial communication protocols rely on the transmission of data objects instead of mere signals This means that the information conveyed by a signal is enhanced with additional relevant details necessary for effective transmission and comprehension by the receiver The assembled package of this information is commonly referred to as a data object.
Data objects
Packing of data
The input signal will have additional data related to the communication added automatically before being transmitted The device doing this is defined as a server in the communication system
The signal information representing attributes of a data object in a data model
The data object from the server is mirrored in the client
Data attributes are updated by subscription
The signal name will be converted to an attribute of the data object
NOTE Data objects are indicated as “DO” in Figure E.1
Figure E.1 – Communication of the signal information as attribute to a data object
Object designation and address structure
IEC 61 850 outlines a standard for numerical communication based on structured addressing, where all data objects are addressed according to IEC 81 346-1 The communication concept must adhere to a hierarchical structure defined in IEC 81 346-1 and utilize letter codes from IEC 81 346-2 However, end users may deviate from these designations if they have an established system, provided it aligns with the structuring principles.
The examples below shows typical address structures as applied in communication according to IEC 61 850
EXAMPLE Position value of a circuit-breaker in a 1 30 kV substation:
(Substation name / voltage level / bay number / metering / logical node data object)
The MMXU logical node is essential for three-phase measurements, offering a comprehensive combination of voltage and current transformer data It measures phase-to-phase voltage, active and reactive power, as well as individual phase currents and voltages, residual current, and additional related information.
Effective communication requires that the addressing of a data object is linked to its corresponding connection node The naming convention for communication may vary from the signal domain designation suggested in IEC 61175 To ensure broader applicability, it is advisable to adopt a functional perspective when designating the signal name within the main process.
Information content (Information object)
The communication server always converts the original signal into a digital representation, which can take the form of Boolean, Integer, Real, or BCD, depending on what best suits the signal's characteristics.
The name of the information in a data object should align with the signal name provided by the signal source, as per IEC 61175 However, it is important to understand that a data object is not the same as the signal name Consequently, the codes for signal class and connection characteristics may be determined by the standard that describes the data object's content, leading to a lack of full compliance with IEC 61175.
A signal name is typically defined by multiple attributes, with the basic signal name represented by one attribute and the signal class indicated by another.
Descriptive parameters
Protocols such as IEC 61 850 enhance original information by incorporating various descriptive parameters For instance, IEC 61 850-7-3 specifies that analogue measurement data is categorized under a Common Data Class (CDC) known as MV (measured value), which is utilized for the measurement information in the aforementioned address structure example.
The CDC itself consists of a number of standardized attributes Table E.1 is a simplified description of the content of the MV CDC
The data attributes include various elements essential for understanding individual samples and their quality The "instMag" represents the value of a single sample, while "mag" indicates the overall value, which may be an RMS or average of multiple samples The "range" attribute assesses whether the value falls within normal limits, and "q" denotes the quality control status, categorizing values as good, questionable, or bad A timestamp ("t") is included when the data object is transmitted, and "subEna" allows for substitution from alternative sources The "subMag" and "subQ" attributes provide the substituted value and its quality, respectively, along with a unique "subID" for identification The "blkEna" attribute indicates if data transfer has been blocked, while "units" specifies the SI unit of measurement Additional optional attributes include "db" for deadband settings, "zeroDb" for initiating transfer, "sVC" for scaled value configuration, "rangeC" for acceptable value ranges, and "smpRate" for the sampling rate Short descriptions ("d") and Unicode descriptions ("dU") may also be provided, with the note that many attributes are optional and can be omitted based on specific application needs.
Annex F (normative) Data element type definitions
General
Data element types (DETs) (sometimes also called “properties”) are used to unambiguously express characteristic properties for objects, especially when information is communicated between computers
Once a DET is hosted in a dictionary, this can serve as an unambiguous common reference for the communication This is vital for the support of electronic business
The standardized full descriptions of Device Element Types (DETs), which include all attributes as per IEC 61 360-1, are found in the IEC Common Data Dictionary for electric and electronic components (IEC 61 360-4).
IEC 61175 specifies data element types and classes in Clause F.2, offering a subset of full descriptions that include the identification number, preferred name, and definition.
NOTE 1 The identification number is listed in the IEC CDD as code under which it is stored in the dictionary
The preferred name and definition attributes are available exclusively in English, as it serves as the reference language for the IEC CDD National language variants can be incorporated into the dictionary under the supervision of the appropriate National Committee.
The DETs outlined in IEC 61175 have been submitted for standardization and inclusion in the IEC CDD, following the procedures specified in Annex J of the ISO/IEC Directives, IEC Supplement: Procedures specific to IEC, 2013 This process aims to ensure that the DETs are accessible in the IEC CDD upon the publication of this part of IEC 61175.
Source definitions of DETs and classes of DETs in this part of IEC 61 1 75
Definitions of classes of DETs
(Class Id) Preferred name Definition
AAF525 signal concept for the identification of a signal connection chain within a given domain conveying information among objects
NOTE Messages (units of signals) may be sent in a communication network in the form of telegrams Such messages may represent one or several signals
AAF526 signal connection concept for the identification of a specific established communication path between different objects used for the transmission of signals
NOTE In IEC 61 1 75: 2005, the name “signal variant” instead of “signal connection” was used
Definition of DETs associated with class AAF525
(Identification number) Preferred name Definition
AAF473 (new) signal class code coded designation of a signal class, based on the classification system as defined in IEC 61 1 75-1 :201 5, Table 1
AAF527 basic signal name short description of the active signal defining the special function of the signal, normally using standardized abbreviations or codes
AAF528 short name short textual mnemonic description of the reporting object or the controlled object, as appropriate for the type of signal
AAF474 (new) signal designation unambiguous identifier of a signal within a system
NOTE 1 According to IEC 61 1 75-1 , the signal designation is composed of several data element types in the sequence: signal class code, basic signal name and short name In this case the data element type signal designation need not be provided in order to avoid possible inconsistencies during transmission NOTE 2 Instead of composing the signal designation by the previously indicated data element types, alternately a flat string may be provided using the data element type signal designation.
Definition of DETs associated with class AAF526
(Identification number) Preferred name Definition
AAF571 signal connection identifier identifier of a specific signal connection
NOTE In IEC 61 1 75: 2005, the name “signal variant identifier” instead of “signal connection identifier” was used
AAF572 signal connection characteristics optional description of technical characteristics of the signal connection NOTE In IEC 61 1 75: 2005, the name “additional information” instead of “signal connection characteristics” was used
IEC 60027 (all parts), Letter symbols to be used in electrical technology
IEC 60050-1 95:1 998, International Electrotechnical Vocabulary – Part 195: Earthing and protection against electric shock
IEC 6041 7, Graphical symbols for use on equipment (available from: http://www.graphical- symbols.info/equipment)
IEC 60445, Basic and safety principles for man-machine interface, marking and identification – Identification of equipment terminals, conductor terminations and conductors
IEC 60447, Basic and safety principles for man-machine interface, marking and identification – Actuating principles
IEC 6061 7, Graphical symbols for diagrams
IEC 60747 (all parts), Semiconductor devices
IEC 61 1 31 (all parts), Programmable controllers
IEC 61 355-1 , Classification and designation of documents for plants, systems and equipment – Part 1: Rules and classification tables
IEC 61 360-1 , Standard data elements types with associated classification scheme for electric items – Part 1: Definitions – Principles and methods
IEC 61 360-4, IEC Common Data Dictionary (CDD), Electric/electronic components (available at: http://std.iec.ch/iec61 360)
IEC 61 666, Industrial systems, installations and equipment and industrial products – Identification of terminals within a system
IEC 61 850 (all parts), Communication networks and systems for power utility automation
IEC 62491 , Industrial systems, installations and equipment and industrial products – Labelling of cables and cores
IEC 62744, Representation of states of objects by graphical symbols
IEC 81 346-2, Industrial systems, installations and equipment and industrial products – Structuring principles and reference designations – Part 2: Classification of objects and codes for classes
IEC 81 71 4-3, Design of graphical symbols for use in the technical documentation of products – Part 3: Classification of connect nodes, networks and their encoding
IEC TS 62771 , Information model covering the contents of IEC 81346-1 and IEC 81346-2, IEC 61175, IEC 61666 and IEC 81714-3
IEC 80000 (all parts), Quantities and units
ISO/IEC 646:1 991 , Information technology – ISO 7-bit coded character set for information interchange
ISO/IEC 7498-1 :1 994, Information technology – Open Systems Interconnection – Basic Reference Model: The Basic Model
ISO 8859-1 :1 998, Information technology – 8-bit single-byte coded graphic character sets – Part 1: Latin alphabet No 1
ISO 1 461 7-6:2002, Graphical symbols for diagrams – Part 6: Measurement and control functions
ISO 21 549-7:2007, Health informatics – Patient healthcard data – Part 7: Medication data ISO 80000 (all parts), Quantities and units
4 Principes fondamentaux 60 4.1 Principes généraux relatifs au transfert et à la dénomination d'un signal 60 4.2 Classification du signal 62 4.3 Domaine de nom de signal 63
The article discusses the designation of signals, outlining the structure of signal designation, which includes general principles, object designation, prefixes, signal names, connection identifiers, and connection characteristics It also recommends specific characters for signal designation and provides guidelines for creating signal designations, focusing on information signals and control signals.
The article discusses the identification of signals within a signal connection network It begins with general information about signal identification, followed by predefined signal names The content further explores the grouping of signals, detailing general principles, signal conditioning within a transport medium, and the organization of signals for presentation purposes.
7 Identification des signaux dans les interfaces pour échange de données 83 7.1 Généralités 83 7.2 Interface entre circuit électrique et dispositifs programmables, E/S 83 7.3 Interface pour la communication logique 83
The article presents a comprehensive overview of signal representation, including the designation of signals and the human-machine interface (HMI) It discusses the importance of documentation in signal presentation and the role of metadata in signal identification Additionally, it includes normative annexes detailing literal codes used in signal names, such as codes for variables and modifiers, as well as the identification of specific designated conductors An informative annex is also provided, covering binary logical representation and general principles, along with signals that involve negation.
Annex C provides examples of signal lists that include signal connection identifiers, focusing on voltage measurement signals of class M and control signals of class C Annex D outlines generic communication needs within a process, detailing process models and signal connection supports, including general wiring, internal and external buses, and human interface presentations It also discusses the applicability of signal designations in electrical systems, control devices with internal digital communication, external communication, and human interfaces Annex E addresses the restructuring of information for communication purposes, covering data objects, data conditioning, object designation and address structure, information content, and descriptive parameters Finally, Annex F defines data element types, including general definitions, sources of data element types (DET), and specific definitions for DET associated with classes AAF525 and AAF526.
The article presents a series of figures illustrating key concepts in signal terminology and transmission Figure 1 depicts the relationship within the terminology framework, while Figure 2 shows a signal with its source and destination(s) Figure 3 illustrates the transmission of information objects through various transport media and signal connection methods Figure 4 highlights different signals generated by logical processing and linking The relationship between control signals and information signals is explored in Figure 5 Figure 6 identifies an object serving as a signal name domain, and Figure 7 details signal designation and connection identification Figure 8 presents the structure of signal names, while Figure 9 provides examples of information signal types Finally, Figures 10 and 11 showcase examples of indication and event signals, respectively.
The article presents various examples of measurement signals, including analog measurement signals in different forms and connection characteristics associated with these signals It also discusses power supply designations and typical command signal types, along with specific examples of command signals and setpoint signals Additionally, it covers signal connection identifiers within a single network and in current measurement circuits, as well as internal signal name identifiers The use of concatenated reference designations in installations is highlighted, along with metadata representing signals and corresponding XML files Furthermore, the article examines binary signal states, examples of signals with negation, voltage measurement in the information signal class, and command signals for disconnectors in the command signal class Lastly, it introduces a communication model based on IEC 81 346-2 and the communication of signal information as an attribute of a data object.
Table 1 presents literal codes for signal classes, while Table 2 provides examples of abbreviated names Additionally, Table 3 illustrates examples of basic signal names Lastly, Table A.1 lists literal codes for variables based on international standards.
80000, Grandeurs et unités 89Tableau A.2 – Codes littéraux utilisés comme modificateurs 90Tableau A.3 – Identification de certains conducteurs désignés 90Tableau E.1 – Exemples d'attributs de données 1 03
ET PRODUITS INDUSTRIELS – DÉSIGNATION DES SIGNAUX – Partie 1 : Règles de base
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La Norme internationale IEC 61 1 75-1 a été établie par le comité d'études 3 de l'IEC: Struc- tures d'informations, documentation et symboles graphiques
Elle a le statut d'une norme horizontale conformément au Guide 1 08 de l'IEC
Cette première édition annule et remplace la deuxième édition de l'IEC 61 1 75 parue en 2005 Cette édition constitue une révision technique
Additional sections of IEC 61175 can be incorporated as technical specifications related to various fields These supplementary parts may serve as application guides for the designation of signals within a specific application context.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'IEC 61 1 75:2005:
– une description améliorée des principes d’utilisation; et
– une séparation stricte entre l'aspect physique d'un signal et les informations associées relatives à ce dernier
Le texte de cette norme est issu des documents suivants:
Le rapport de vote indiqué dans le tableau ci-dessus donne toute information sur le vote ayant abouti à l'approbation de cette norme
Cette publication a été rédigée selon les Directives ISO/IEC, Partie 2