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Up to now the definitions of functions have been used implicitly according to the ECLASS function symbols (IEC 81346 - https://wiki.eclass.eu/wiki/CAx_Funktionssymbole). See Section 5.12.12.3.2, “Connections, IEC function symbols”. In this chapter we consider the necessary steps to enhance with a fully user-defined function definition building on existing data analogously to above mentioned chapter. This happens without changing any existing data.
Just to recap the introduced IEC symbols once again let's have a quick look on the classification's basic structure. Central point was the setting of (real/physical) connections CNS_CP|4|3 (Electrical Connection). The basic functional structure is defined by the attribute Connection EclassSymbolMap and the respective connection is integrated into this structure. Following figure describes the present situation with the help of an example using 3 functions, where the first function has one (logical) connection, the second two (logical) connections and the third three (logical) connections. In order to keep the example abstract the functions' names shall be given by SYMBOL1, SYMBOL2, SYMBOL3, the connections' names by A,B,C,D,E.F.
Definition of the functional structure with the help of an example. Real connections are integrated in the functional structure.
The previous considered case was in relation to names of functions with a certain "implicit meaning", namely the IEC function symbol given by the name. Often these pre-defined functional definitions are not sufficient or it is intended to explicitly specify the electrical functionality. In these cases the definition of the functional structure explained under Section 5.12.12.3, “Classification of Electrical Connections [CNS_CP|4|3])” is kept without limitations.
The innovation lies in the classes CNSELEK|5|8|1 to CNSELEK|5|8|7, which explicitly specify a node's electrical function in the functional structure. As a consequence you can classify in the way as before; especially the limitations to the IEC function symbols in the attribute Connection EclassSymbolMap are completely omitted.
In essence, for each node in the functional structure, an instance of CNSELEK|5|8|x is created (so in above example three). So an instance of these functional classes describes a set of real connections.
Now all these connections shall be specified in more detail by an instance of the functional classes; for this the respective function class instance has only to be linked with the respective node in the functional structure. The linking with this node is achieved by the first part of values of Connection EclassSymbolMap. In above figure this is exemplified by the blue box.
Together with the symbol representation described under Section 5.12.12.5, “Symbol representations (Circuit symbols) "Advanced" ” the presented schema allows fully flexibility in the machine-readable functional/symbolic description of an electrical part in fully analogy to the definitions of ECLASS Advanced or EPLAN.
These classes CNSELEK|5|8|x mirror the functionality of the ECLASS Advanced block AAQ676. An exception make cables which are differently, but equivalently (mutually convertible) modelled as described above.
CNSELEK|5|8|1 Main Function: Only one instance of Main Function is allowed per article. Their exact meaning depends on context. For PLCs[54] the pins for power supply are summarized under the Main Function.
CNSELEK|5|8|2 Contact Function: Functions summarizing pins belonging to contacts and protective circuitry, meaning changeover contacts or switches, etc.
CNSELEK|5|8|3 Terminal Function: Functions summarizing pins belonging to a terminal. Here, especially the potential can be determined/modified, if this is not already done in the ECLASS function symbols.
CNSELEK|5|8|4 Communication interface: Functions summarizing pins enabling the communication with other parts especially at PLCs (e.g. LAN adapter). Among others, the communication protocol or the type of interface (e.g. PROFINET, TCP/IP,...) can be determined here.
CNSELEK|5|8|5 Input/Output: This class mostly represents the "PLC pins". For example, to determine if respective pins are analog or digital input/output, type of measurement, signal behavior, etc.
CNSELEK|5|8|6 Electromechanical Drive Function: This class summarizes pins belonging to electromechanical actuators. A good example are coils driving switches at relays, etc.
CNSELEK|5|8|7 Signal converter Function: These classes describe pins belonging to transformers, rectifiers and other signal adapters.
Within these 7 classes there are attributes which further specify specific functions.
All these classes have 6 attributes in common:
For example, in the case of CNSELEK|5|8|3 Terminal Function the potential of all related connections can be determined by the attribute Terminal potential. Another important point is that each of these function class instances is responsible for a number of connections (CNS_CP|4|3). The following describes this mapping between function and connections exemplarily.
The linking between function and all related pins is achieved by the mandatorily specified attribute Symbol/Function Number. The functioning of this attribute is explained with the help of following example. We consider a model with three functions, once with one pin, once with two pins and once with three pins.
| Value of attribute in Connection EclassSymbolMap (CNS_CP|4|3) |
| SYMBOL1||1||1 |
| SYMBOL2||2||1 |
| SYMBOL2||2||2 |
| SYMBOL3||3||1 |
| SYMBOL3||3||2 |
| SYMBOL3||3||3 |
In this case 3 function classes of CNSELEK|5|8|x have to be instantiated. (The following figures show CNSELEK|5|8|3.)
| Attribute | Class instance | Value |
| Symbol/Function Number | 1 | SYMBOL1||1 |
| Function Name | 1 | SYMBOL1 |
| Symbol/Function Number | 2 | SYMBOL2||2 |
| Function Name | 2 | SYMBOL2 |
| Symbol/Function Number | 3 | SYMBOL3||3 |
| Function Name | 3 | SYMBOL3 |
With this scenario we have enriched a number of pins with a function specification. For example, this allows the customization of the pre-defined IEC function symbols with own data. The function name in Connection EclassSymbolMap doesn't need to match the attribute Function Name; Function Name "overwrites" the function name in most target systems. Normally they should stay the same.
The central point of this construction is the "linking" of a group of pins (belonging to a function) with a new instantiated function class. The attributes of this function class affect all pins belonging to the function.
Linking between electrical connection in 3D (CNS_CP|4|3) via attribute "Connection EclassSymbolMap" with the respective symbol pin; for example, SYMBOL3||3||3 corresponds to the 3th pin of the 3th function of the model, given by the identifier SYMBOL3. This represents the previous situation.
The previous use of functions and symbols is shown in above figure. Models, designed in this way can be used for the described enhancement without limitation. The decisive point is that by instantiating the function classes CNSELEK|5|8|1 to CNSELEK|5|8|7, the properties of the pre-defined IEC function symbols can be modified or explicitly specified.
Let's say we want to explicitly adjust a component's or component's function potential. The following figure shows this situation. Besides the attribute values of description and short description the terminal's potential is explicitly set by the attribute Terminal potential to neutral conductor. The linking to the situation shown above is established by the Symbol/Function Number with its value SYMBOL1||1.
Explicitly instantiated function class analogously to previous figure. The linking to all connections of a function happens via attribute Symbol/Function Number with the value SYMBOLx||x. Accordingly the potential of all pins (in this example only one) is set to "neutral conductor" by the attribute "Terminal potential".
The key aspect of this exemplary construction is that the original element of the functional structure introduced by Connection EclassSymbolMap is modified by the one explicitly determined under CNSELEK|5|8|3. Another important use case is that this construction enables a complete new definition of own functions, which are not yet described by the IEC standard. Besides these classes enable to assign a user-defined symbol via attribute Symbol Reference (compare below).
The above described classes allow the differentiation between function and symbol by analogy with systems like ECLASS Advanced and EPLAN. We consider a model correctly classified as described above. That means Connection EclassSymbolMap is correctly set in the connections. Furthermore these connections are enhanced by respective function class instances.
In this use case it's very easy to assign a specific symbol to this function (inclusive meta data, meaning the symbol graphic as DXF, 2D pin coordinates within the DXF and other properties). Furthermore there is already a specific symbol catalog within the main catalog path.
Typical situation of a catalog enriched by a symbol catalog. The symbol catalog is a catalog with a specific form. The single project files (NOCAD) only contain classification information and "Additional export formats" in the DXF format. In this way "building blocks" for symbols are provided, which can be referenced by the projects of the main catalog (also repeatedly).
The attribute Symbol Reference allows the integration of a symbol into the main part or in a specific function of the main part.
For this the following steps have to be processed:
The symbol project from the symbol catalog is embedded in the main part via crosslink.
The symbol from the symbol library is referenced by a (compatible) function of the main part. This happens by the attribute Symbol Reference. Compatible in this context means that the number of pins from symbol and function corresponds.
Important for this construction is that both function and symbol contain an "internal structure". Mapping a function with e.g. 3 connections to one with 2 connection will result in an error.
