Fanuc alarm: 251 - ATC ERROR

This alarm is issued in the following cases (DRILL-MATE): An M06T_ command contains an unusable T code. An M06 command has been specified when the Z machine coordinate is positive. The parameter for the current tool number (No. 7810) is set to 0. An M06 command has been specified in canned cycle mode. A reference position return command (G27 to G44) and M06 command have been specified in the same block. An M06 command has been specified in tool compensation mode (G41 to G44). An M06 command has been specified without performing reference position return after power-on or the release of emergency stop. The machine lock signal or Z-axis ignore signal has been turned on during tool exchange. A pry alarm has been detected during tool exchange. Refer to diagnosis No. 530 to determine the cause.