Devices are logical electronic or fluid-technical (hydraulic or pneumatic) units. They are named with a device tag (DT), like M1, K1, X1, XS1, W1. Devices are created when functions used in the project have the same DT. The identical designation via the DT thus determines the logical relationship.
A device can consist of multiple items or just one item. An item is part of the device which cannot be further broken down, such as a motor, terminal, plug (male pins, not female pins!), auxiliary block, or cable.
A part number can be assigned to an item, i.e. an item normally represents a part. Items can be graphically displayed on the mounting panel.
Items only have meaning in connection with parts management and working with defined devices, but not for logical system behavior (copying, deletion, "use existing" etc.). The electronic, hydraulic, or pneumatic behavior of an item is represented by functions. Each item may contain one or several functions.
A function can be placed in the schematic and represented by a symbol. A placed function is called a component. A component, therefore, connects logic with graphics. The symbol contains only graphics, while the logical information comes from the function (actually: from the function definition).
This means that you always place functions in the schematic, never items!
Functions are distinguished as main and auxiliary functions. The main function represents the device. Only the main function can be assigned to a part, and the device definition is stored with the main function through the part.
The following illustration clarifies the structure of devices with the example of a contactor:
|
Device (Contactor K1)
Item (contactor - auxiliary block)
Function (coil - Power NO contact - auxiliary NO contact)
Component | Mounting diagram
Symbols from the symbol library |
Device K1 consists of two items: a contactor and an auxiliary block. Thus both have the same device tag K1.
The contactor has several functions, e.g., a coil, a power NO contact, an auxiliary NO contact, etc. The coil is the main function, i.e. it represents the device and can be assigned a part.
These functions can be represented graphically in the schematic with symbols. If you add a symbol from an EPLAN symbol library (such as a coil), these symbols already have functions assigned to them. Therefore, along with the symbol you are placing the function. The result is a component. This component has certain properties which come with the function. In addition, you can specify additional properties for any component.
If you have assigned one or more part(s) to the device, then you can place the corresponding item on a page of type "panel layout".
See also