Description
When optimising processes, it can be and advantage to know future contour elements in advance. The CNC can supply them using the contour look-ahead function.
The PLC can use these elements to optimise the process parameters. Data provision is either programmed by NC commands or by request from the PLC.
The data provided for future contour elements are:
- Type of contour element: Linear block, circular block, polynomial block
- Block number
- Start position of the contour element
- Length of the contour element
- Swept angle, programmed and compensated radius
- Program line number
- Length of the scales geometry for die sinking EDM
Sequence of a PLC request
The PLC sends a request to the CNC. The request contains either an index that belongs to a motion block ore a distance based on the program start.
There are 2 modes for these two different requests:
- Mode 1: Request via the index.
- Mode 2: Request via distance from program start.
The CNC then sends the reply information to this request for each motion block. The process looks like this:
