Synopsis:
For machining very large programs on a general purpose CNC, the internal part program memory may become a constraint. This is usually the case with CAD generated programs for Die milling where the program size may run into the range of 20-30Mb, which is far beyond the capacity of a standard Fanuc-0 control. To execute such programs the alternatives are:

a) Breakup the programs to smaller manageable chunks as per the memory capacity of the control and execute it one by one.

b) Use the DNCI function available with the control.

Option a) is cumbersome since a lot of pre-processing has to be done to break up the program and while machining, after execution of every chunk the part program memory must be cleared, a new chunk loaded and executed. This involves a lot of operator intervention and may result in serious accident if a chunk out of sequence is loaded. This is where the DNCI option can be a big advantage.

What is DNCI?
DNCI is an add-on to the AUTO mode of the CNC where instead of executing the part program from the memory of the CNC, it executes program blocks dynamically transferred to it through the RS232 port. This article explains how to set up the DNCI and successfully execute programs.