Siemens Mixing Inches and MM

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Using R Parameters Siemens Sinumerik 828 840

R Parameters Siemens, on a Siemens control you can use R parameters to control a program externally.

“What’s he on about” I hear you say.

I’ll explain.

Imagine a sub program that has no value assigned to it’s feedrate. Well you could call the feedrate R1

G1 X50. F=R1

The program says to you “ok I’ll feed at R1” it thinks for a while then says

“what’s R1 David?” (Actually it wouldn’t know my name)

So you tell it.

R1=200.
G1 X50. F=R1 

So now it’s just like you wrote

G1 X50. F200.

Now I know what you are thinking saying, “just program that in the first place you prick.”

When you use this type of programming, known by posh people like me as parametric programming, you can program a shape then give it the dimensions externally.

You would usually have the shape in some kind of subprogram.

It’s All in The Pizza

It’s like ordering a pizza. They know you want a pizza but then they need to know all the other stuff like what size and what topping.

Anyway fuck the pizzas let’s talk about R values.

The difference is you can put whatever value you want in R1.

You could then use the same program to rough and finish the part. The first time you call it you put R1=100. the second time you put R1=200.

Fanuc uses a similar thing using # (sometimes called variable).

Instead of R1=6 it has #1=6. (you get loads of variables, #1 to #100 and more)

Heidenhain uses Q values Q1 = 6.

See how Fanuc do this.

See how Heidenhain do this.

Wait There’s More

You don’t just have to use R1 there are at least 99 of these bloody things.

You can use R2 R3 or R65 it’s entirely up to you, just don’t get confused that’s all.

Then comes the clever shit. You can actually do maths with them. You could put R1= R1 – 10.

This would take 10. off the feedrate.

You can even do things like cosines and sines and stuff like that. The mind boggles.

If you have a probing system then it will almost certainly be using R parameters in the background to grab data and the get the size information you want.

(Picture of my puppy for those who’d rather be on Facebook his name s Tallywacker)

You can program a shape and replace all the dimensions with R parameters. This is when it gets fuckin awesome.

The program below uses an R parameter for the corner rads and an R parameter for the width.

The left side is the main program. The right side is the sub program called each time.

Here is a video of the program in action.

Siemens Training 828 840D

These methods are all tools in your programming toolbox. One day you’ll see a use for one of them and you’ll think “I remember that grumpy old bastard wrote an article on that”.

Then I hope you’ll return to this article.

Thanks for watching and reading

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