The black box is a popular method of representing devices for which no symbol exists in a symbol library prescribed by the end customer. Black boxes are used in various different ways:
- For devices / assemblies that are not in the symbol library
- For devices / assemblies that are not complete in the symbol library, e.g., with missing PE / PEN connection points
- For representing PLC assemblies
- For representing complex devices, e.g., frequency converters; these devices are drawn over several schematic pages and cross-referenced
- For representing several symbols under a single device tag, e.g., a motor with brakes
- For representing spare cable connections in cables (without a black box, the "Cable connection without cable" error message is generated)
- For nesting several device tags, e.g., for a device with several terminal strips:
Device: -A1, terminal strips: -X1 and -X2
The nesting allocates the device tags -A1-X1 and -A1-X2 to the terminal strips. - For allocating device tags to terminals, since the terminal DT can't be moved (because otherwise the connection point designation would also be moved), for example required due to a lack of space on the page
- For special protection devices that cannot be represented using the normal symbols, but which must also display a contact image.
See also