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Programmable on/off for block delete switch

As you probably know, the block delete function (also called optional block skip)involves an on/off switch mounted on the control panel.With most Fanuc controlled machines, this is a physical switch – often a toggle switch – that is manually activated. In the off position, any time the machine sees a slash code (/) in the program, it will act on the words that are to the right of the slash code. If the block delete switch is off, the machine will ignore what is to the right of the slash code.

Consider this example:

  • N015 G43 H01 Z0.1 /M08

If the block delete switch is turned off, the M08 word will be acted upon and coolant will come on. If the block delete switch is turned on, the M08 word will be ignored and coolant will not be activated.

Again, with most machines block delete is controlled by a physical switch. You may come up with an application, however, in which you want to program whether the switch is on or off.

Unfortunately, if your machine has a physical switch, like a toggle switch, this may not be possible. But if the block delete switch is more “electronic”, like a lighted button, check the machine’s M code list to see if there are M codes to control the condition of the block delete switch. One M code may turn it on while another turns it off.

If you find you the machine doesn’t have the related M codes, note that you can probably handle the application with parametric programming techniques. Consider the coolant example again.

  • O0001#100 = 1 (Flag for condition. 1: coolant on, 2: coolant off)




(When the coolant choice must bemade in the program:)

If [#100 EQ 1.0] GOTO 5 (Test forcoolant)

M09 (Leave coolant on)


N5 M08





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