Electrical engineering devices are connected to each other to configure plants. These devices have physical properties that are specified by the manufacturer and have to be considered by the designer.
As a designer you either work with device definitions whose symbols are then used graphically or you create the required schematic and then later take care of the device selection. Any feasible mixing of components is possible in the process.
If you work with a device definition, Eplan checks and reports whether the corresponding device was changed afterwards in a way that it does not correspond to the manufacturer specifications anymore. Since there are also many devices that are composed of different parts, only you as a user can decide what a correct device definition (part compilation) is.
Example:The "auxiliary contactor with 1 NO contact and 1 NC contact" device is selected. If a contactor coil or a NO contact is now drawn in the schematic, everything is okay and the device functions: There is an NC contact that is not required (this contact is free, this means non-placed).
If, however, a contactor coil with two NO contacts is drawn into the schematic, the device definition is incorrect: An NO contact is used in the schematic that is not physically available.
There are two possibilities for such cases:
- Eplan reports an error that must be solved.
- Eplan does not permit this state.
- Eplan only permits this state after querying.
So that such errors can be detected, Eplan must know the correct device specification. For this reason it is possible to create a function pool for a device. (Whether these functions are placed or not does not play a further role at all.) A controllable function pool can only be realized via a device selection: Only if a device definition was assigned, can non-placed functions be checked for errors and these then reported.
See also
Spare Items: Device Definitions
Spare Items: Function Templates