Programming - 770MX

In This Section, You'll Learn:

About the languages that are understood and interpreted by PathPilot.

Before You Begin

• Referring to This Section Use this section only for reference. To learn about the principles of the control language (so that you can write programs by hand from first principles, for example), we recommend that you consult an introductory textbook on G-code programming.

• Creating and Editing G-Code Files We recommend using a text editor like Gedit or Notepad++. Don't use a word processor to create or edit G-code files — it'll leave unseen codes that could cause problems or prevent a G-code file from working.

Programming Overview

Read the following sections for a G-code overview:

About G-Code Programming Language

A G-code program is made up of one or more lines of code. Each line of code is called a block, and can include commands to the machine. Blocks are collected into a file, which makes a program.

A block is normally made up of an optional line number at the beginning, followed by one or more words, which groups the elements together into a single statement.

A word is a letter followed by a number (or, something that evaluates to a number). A word can either give a command or provide an argument to a command.

A program is one or more blocks, each separated by a line break. Blocks in a program are executed either:

• Sequentially (from the top of the program to the bottom)

• Until an end command (M02 or M30) is encountered

Example:
G01 X3 is a valid line of code with two words:

• G01 is a command: the machine should move in a straight line at the programmed feed rate.

• X3 provides an argument value: the value of X should be 3 at the end of the move.

Most commands start with either G (general) or M (miscellaneous) — G-codes and M-codes.

There are two commands (M02 and M30) that end a program. A program can end before the end of a file. If there are lines in a file after the end of a program, they're not meant to be executed in the normal flow (they're generally parts of subroutines).

G-Code Formatting Reference

A permissible block of input code is made up of the following programming elements, in order, with the restriction that there is a maximum of 256 characters allowed on a line:

1. (Optional) Block delete character (/)

2. (Optional) Line number

3. Any number of words, parameter settings, and comments

4. End of line marker (carriage return or line break)

Programs are limited to 999,999 lines of code.

Spaces and tabs are allowed anywhere on a line of code and do not change the meaning of the line, except inside comments. Blank lines are allowed in the input, but they're ignored. Input is not case sensitive (except in comments), so any letter outside a comment may be in uppercase or lowercase without changing the meaning of a line.

Example
G00 x +0. 12 34y 7 is equal to G00 x+0.1234 y7

A line may have:

• Any number of G words, but two G words from the same modal group may not appear on the same line.

• Zero to four M words, but two M words from the same modal group may not appear on the same line.

• For all other legal letters, a line may have only one word beginning with that letter.

Any input not explicitly allowed is illegal, and causes the interpreter to either signal an error or ignore the line.

PathPilot omits blocks of code that are prefixed with a block delete character (/).

PathPilot sometimes ignores things it doesn't understand. If a command doesn't work as expected, or does nothing, make sure that it's correctly typed. PathPilot doesn't check for excessively high machining feeds or speeds, and it doesn't detect situations where a legal command will do something unfortunate (like machining a fixture).

Line Numbers

A line number is indicated by the following, in the order listed:

1. The letter N

2. An integer (with no sign) between 0 and 99,999,999 (which must be written without commas)

Line numbers may be repeated, or used out of order, but that's rare in normal practice. A line number isn't required, and is often omitted.

Words

A word is indicated by the following, in the order listed:

1. A letter other than N or O

2. A real value

Letters

Words may begin with any of the following letters, except N or O:

NOTE: Several letters (I, J, K, L, P and R) may have different meanings in different contexts.

Values

A real value is one of the following:

• An explicit number (like 341, or -0.8807)

• An expression (like [2+2.4])

• A parameter value (like #88)

• A unary operation value (like acos[0])

NOTE: In the command examples that we use, the tilde symbol (~) stands for a real value. If L~ is written in an example, the ~ is often referred to as the L number. Similarly the ~ in H~ may be called the H number, and so on for any other letter.

A number is a subset of a real value. Processing a real value to come up with a number is called evaluating. An explicit number evaluates to itself.

Explicit numbers have the following rules (in this case, a digit is a single character, 0 through 9):

• A number must consist of the following, in the order listed:

  • An optional plus or minus sign

  • Zero to many digits

  • (Optional) One decimal point

  • Zero to many digits

• There must be at least one digit somewhere in the number.

• It must be either an integer (no decimal point) or a decimals (decimal point).

• It may have any number of digits (subject to line length limitations).

NOTE:  PathPilot only keeps 17 significant figures, which is enough for all known applications.

• A non-zero number with no sign as the first character is assumed to be positive.

Initial zeros (a zero before the decimal point and the first non-zero digit) and trailing zeros (a zero after the decimal point and the last non-zero digit) are allowed, but not required. A number written with initial or trailing zeros has the same value when it is read as if the extra zeros were not there.

Numbers used for specific purposes by PathPilot are often restricted to some finite set of values, or to some range of values. In many uses, decimal numbers must be close enough to an integer to be accepted as a valid input. A decimal number which is supposed to be close to an integer is considered close enough if it is within 0.0001 of an integer.

Order of Execution

If a parameter setting of the same parameter is repeated on a line (like #3=15 #3=6), only the last setting takes effect. It's illogical, but not illegal, to set the same parameter twice on the same line.

The order of items on a line doesn't determine the order of execution on the commands.

Three types of items' order may vary on a line (as given earlier in this section):

• Word May be reordered in any way without changing the meaning of the line.

• Parameter Setting If it's reordered, there is no change in the meaning of the line unless the same parameter is set more than once. In this case, only the last setting of the parameter takes effect.

Example
When the line #3=15 #3=6 is interpreted, the value of parameter 3 is 6. If the order is reversed to #3=6 #3=15 and the line is interpreted, the value of parameter 3 is 15.

• Comment If it contains more than one comment and is reordered, only the last comment is used. If each group is kept in order or reordered without changing the meaning of the line, then the three groups may be interleaved in any way without changing the meaning of the line.

Example
G40 G01 #3=15 (foo) #4=-7.0 has five items and means exactly the same thing in any of the 120 possible orders, like #4=-7.0 G01 #3=15 G40 (foo), for the five items.

The order of execution of items on a line is critical to safe and effective machine operation. If items occur on the same line, they are executed in a particular order. To impose a different order (like to turn coolant off before the spindle is stopped), code the commands on separate blocks.

The order of execution is as follows:

1. Comment (including message)

2. Set feed rate mode (G93, G94, G95)

3. Set feed rate (F)

4. Set spindle speed (S)

5. Special I/O (M62 to M68)

NOTE: This is not supported.

6. Change tool (T)

7. Spindle on/off (M03, M04, M05)

8. Save State (M70, M73, restore state (M72), invalidate state (M71)

9. Coolant on/off (M07, M08, M09)

10. Enable/disable overrides (M48, M49, M50, M51, M52, M53)

11. Operator defined commands (M101 to M199)

12. Dwell (G04)

13. Set active plane (G17, G18, G19)

14. Set length units (G20, G21)

15. Cutter radius compensation on/off (G40, G41, G42)

16. Tool table offset on/off (G43, G49)

17. Fixture table select (G54 through G58 and G59 P~)

18. Set path control mode (G61, G61.1, G64)

19. Set distance mode (G90, G91)

20. Set canned cycle return level mode (G98, G99)

21. Home, change coordinate system data (G10) or set offsets (G92, G94)

22. Perform motion (G00 to G03, G12, G13, G80 to G89 as modified by G53)

23. Stop (M00, M01, M02, M30, M60)

Modal Groups

G- and M-codes are, generally speaking, modal — they cause the machining system to change from one mode to another. The mode stays active until another command changes it implicitly or explicitly.

Example
If coolant is turned on (M07 or M08), it stays on until it is explicitly turned off in the program (M09).

A few G-codes and M-codes are non-modal (like Dwell (G04)). These codes have effect only on the lines on which they occur.

Modal commands are arranged in sets, called modal groups. Only one member of a modal group may be in force at any given time. In general, a modal group contains commands for which it is logically impossible for two members to be in effect at the same time (like inch units (G20) vs. millimeter units (G21)).

A machining system may be in many modes at the same time, with one mode from each modal group being in effect.

For all G-code modal groups, when a machining system is ready to accept commands, one member of the modal group must be in effect. There are default settings for these modal groups. When the machining system is turned on or re-initialized, default values are automatically in effect.

Modal groups for G-codes are detailed in the following table.

Modal groups for M-codes are detailed in the following table.

Non-modal G-codes are:

• Group 0 {G04, G10, G28, G30, G53, G92, G92.1, G92.2, G92.3}

Comments

You can add comments to lines of G-code to help clarify the intention of the programmer. To embed a comment in a line, use parentheses. To add a comment to the end of a line, use a semicolon.

NOTE: The semicolon is not treated as the start of a comment when it's enclosed in parentheses.

Comments can appear between words, but they can't be between words and their corresponding parameter.

Example:
S100(set speed)F200(feed) is okay, but S(speed)100F(feed) is not.

Supported G-Codes Reference