Standard configuration of CNC tasks

By default, the CNC consists of 3 tasks which can be implemented in a real-time operating system.

• COM task: Driver supplying display values for a user interface.
• SDA task: Consists of the decoder, calculation of tool radius compensation and interpolation preparation (DEC, TRC, PPREP).
• GEO task: Executes the actual cycle-synchronous interpolation, i.e. generates the cyclic axis command values and outputs to the drives.

Depending on the CNC application, the CNC tasks can be prioritised differently and assigned with corresponding cycle times.

Below are examples of several criteria that affect the tasks:

• The COM task affects the transfer rate of objects for the user interface and can be adapted depending on the response time of the display.
• It is recommended to adjust the SDA task for HSC machining which involves a high volume of short motion information. It is advisable to select a short cycle time for the SDA task (decoder) in order to supply the interpolation with a sufficient number of motion blocks and achieve the required programmed velocity (data throughput, block cycle time).
• In general, the GEO task must run synchronously with the bus cycle time so that the drive receives a new command position in each cycle.