Function and characteristics

Any values can be exchanged via external variables between CNC (NC channel), graphical user interface (GUI) and PLC, whereby the variables are handled transparently by the CNC, i.e. the significance of the variables is determined purely by the application (NC program, graphical user interface and PLC). The CNC only has the task of transporting these variables and making them available to the user in the NC program. During the configuration phase, a name, a type, access rights (write and/or read) and a memory location are assigned to the external variables. The external variables are configured on the basis of an ASCII list only once during boot-up.

In addition to the simple variables, it is also possible to create one-dimensional fields which are accessed with indexing. The variables can be created in a channel-specific or also cross-channel memory. The values apply throughout the lifetime of an NC-program, i.e. they are not cleared for instance when a new NC-program is started.

There are two options determining the instant of writing/reading a variable from the NC-program:

  1. Writing/reading of a variable is performed synchronously with current NC-program execution, i.e. the temporal sequence of the NC-commands and variable access operations is ensured.
  2. Writing/reading of a variable is performed at the time of decoding.

Access via the GUI or the PLC is non-synchronous with respect to NC-program execution.

Use of external variables
Use of external variables