Understanding Custom Macro Version A

Custom macro B is the more powerful and desirable version of custom macro. However, there are still control models that can be equipped with custom macro version A, so never assume that a given machine you plan to purchase will be (or can be) equipped with custom macro B.  

 

One limitation of custom macro A is that you cannot use a decimal point in custom macro commands. All values must be expressed as integers. If you know the fixed format for certain CNC words, this isn’t too bad.

 

For example, if you’re working in the Imperial (inch) system and want to express an X word of 10.0 inches, the fixed format (with no decimal point) for most machines is X100000. Whenever performing calculations, or providing input data, you must use integers.

 

With custom macro B, a G65 is used to call a custom macro. This is not the case with version A in which case a G65 simply specifies that the command is custom macro. An H word specifies what kind of command is being given.

 

This gets a bit confusing, because every kind of arithmetic and logic command has its own H word—and unless you have all the H-word values memorized, you can’t simply scan a custom macro A program and tell what is happening. Three letter addresses—P, Q and R—are used within G65 commands to further clarify what is actually happening. Here are some examples showing the basic arithmetic functions:

 

 

Note that only one arithmetic operation can be performed per command, meaning some expressions must be divided into multiple commands. Consider the following command given in custom macro B format:

 

 

This requires two commands in custom macro A:

 

 

Custom macro A programs are tedious to write and interpret. I always recommend writing the custom macro in version B first, then converting it to version A.

 

Here is a more complete example. This custom macro will machine a bolt pattern of holes. First let’s look at the main (calling) program:

 

 

Notice that every input variable (argument) must be specified in a separate equality command.

 

Now, here is the custom macro. We’ve placed the equivalent custom macro B command in parentheses after each version A command: