Cause : 4th G-function not allowed comes when the NC block which was read in contains an illegal 4th G function. The NC program number and NC block number in which the NC block decoder detected the error can be read out with the "output actual values - decoder error location" task.

1. MDI mode:No 4th G function is allowed.
2. Automatic/single-block mode:Define a legal 4th G function according to the table (see the Programming Guide).