Status and display information

The status information is transferred unidirectionally from the CNC to the PLC. This data is constantly refreshed by the CNC and can be read by the PLC if needed. The status information is updated without informing the PLC. Updating is not protected by a handshake protocol or semaphore mechanism.

With long PLC cycle times, the PLC does not record each short-term change under certain circumstances but is only informed of the current status.

Status information is exchanged on the HLI via memory. The transfer direction is defined for each status information item. The status data is transferred on the HLI as far as possible as single elementary data items (byte, Boolean, integer etc.).

The status information is combined depending on the CNC-internal structure to enhance structuring.

The diagram below shows the internal structure of the CNC in simplified form:

The CNC is subdivided into the modules:

• Dec (Decoder): Module for decoding the NC program. This module converts the CNC program into an internal control data format and executes a number of different calculations, such as parameter calculation etc. Timewise, the decoder runs ahead of actual processing and under certain circumstances may be several hundred NC blocks ahead of current processing.
• Bavo (path preparation, look-ahead): Module to calculate dynamic limit values based on the set parameters. It detects corners and triggers geometry changes. The Bavo also runs asynchronously with current processing and under certain circumstances may be several hundred NC blocks ahead of current processing.
• Ipo (interpolator): Module to generate individual positions for the current cycle, allowing for programmed and maximum velocities etc. . The interpolator represents the current state of the machine.