Jump Around Using M99 Plus Block Skip

Jump Around Using M99 Plus Block Skip

Using M99 Plus Block Skip

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M99 Plus Block Skip, M99 on a Fanuc, Haas or Mazatrol ISO control can be used to jump sections of code.

Learn to use this in conjunction with the block skip command to switch it off and on.

Now I know you are all thinking “Dave you’re wrong it’s the end of a sub-program”. (Please in the name of holy shit do not call me Dave.)

Well you are right and you are wrong.

Yes it means continue and is used at the end of a sub program.

But it also has another nifty use.

Imagine you want to skip a complete section of program in the case below it’s the Spot Drill.

Let’s See Some Crap Ways Of Doing This

(If you want to do this on a Toshiba Tosnuc 888 or similar control go to the end of the article)

In this example it’s a spot drill we want to miss out.

M99 Plus Block Skip
Standard Code

You could delete it and make two programmes (sounds like hard work and loads of errors). Not to metion wear on your finger tips. Truth is it’s just a shit way to do it.

M99 CNC Code
Block Skip

The programme above  contains BLOCK SKIPS sometimes called BLOCK DELETES.

When you switch on your BLOCK DELETE/BLOCK SKIP switch, each time a forward slash (/) is seen that block will not be processed and the control will move on to the next block.

M99 Plus Block Skip

On most Fanuc controls it’s B.D.T not to be confused with CBT (Cock and balls torture) please do not google this in company time.

It works ok but it is very time consuming. If you want to skip a big section of code you will have to write in loads of block skips.

Call me a lazy bastard but I definitely couldn’t be arsed with that.

Some controls even have two three and four block skips so you can switch on any combination of these switches, mmmm complicated. Good luck with that one.

Do You Have Adequate Life Insurance?

M99 CNC Code (Now let’s use it)

The next example is the easiest way.

You probably normally see an M99 at the end of a sub programme.

In the case below it tells the control to jump to N100 (M99 P100).

The P part is the N number you want to jump to.

M99 P600 (Jump to N600)
M99 P6666 (Jumps to N6666)


M99 Plus Block Skip

If you put the BLOCK SKIP/BLOCK DELETE on it will not jump the spot drill.

You would have a choice. If you temporarily want to skip a section of code.

Be careful what N Numbers you choose so as not to mix them up.

Maybe you broke all the taps and you don’t have anymore so you want to skip the tapping. In this case I’d just jump with M99 and then take it out before saving the program.

However, see the next Example.

For this last example you might have to think a bit. Call me finicky but I like the BLOCK SKIP/BLOCK DELETE as a default to be off.

Most machines now don’t have a mechanical switch for BLOCK DELETE/BLOCK SKIP so when you turn on the machine block skip will always be off.

That means the default would be to jump the code.

My way of looking at it, is that you would want the default to be running the whole program as normal.

So We Are Agreed

The default should really be the way the programme was originally done.

In the example below if the block skip is off, which it will be when you start up your machine.

The first thing it will do is jump over the bit that tells it to jump the code.

Meaning it runs as normal not jumping any tools.

The Clever Shit (M99 Plus Block Skip)

M99 Plus Block Skip
What’s This?

Now I know this is a bit confusing and maybe I didn’t explain it too well. Trust me it works.

What’s the matter with you lot just take some time to fuckin read it.

Sorry I’m losing my temper a bit here, the dog’s just pissed on the TV remote again. Just read through it a few times and the penny will drop.

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Where the teacher is never angry.


Yes you can do this with GOTO

This is my pet Cockroach his name is Boris

GOTO 100
Same as M99 P100

To do this you must have the Macro Option if you don’t then this is where M99 comes in handy.

Best way to see if you have macro is to try using it in MDI.

In MDI Type in #1=6 if you have macro it will work if you don’t you’ll get an alarm and your machine will self destruct in 15 minutes.

Jumping Sections of Code on a Toshiba Tosnuc 888 or Similar

This is how you do it on a Toshiba (the blue bit).

Don’t forget it’s GO (that’s G and letter O) not G0 which is G and number zero (Rapid Command).

Don’t get your letter O’s and your number zeros mixed up.

/M99 P50                                   /[GO,50]               (JUMP TO N50)
M99 P100                                    [GO,100]            (JUMP TO N100)
N50                                              N50                      (ARRIVE HERE
N100                                            N100                      (ARRIVE HERE)

Without Fancy Shit  (Just jump some code)

M99 P100                                    [GO,100]            (JUMP TO N100)
N100                                            N100                      (ARRIVE HERE)

If you have macro you can do a similar thing on Mazak, Haas or Fanuc.

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