M23: Select File

Issuing an M23 selects a file from the SD card that will be used for printing with the M24 command.

The file will remain “selected” and all subsequent M24 commands will print that file until a different file is selected.

Error Handling

If the file does not exist on the SD card, an error will be returned (ERROR?).

Restarting Files

The M23 command can be used to restart a file from the beginning.

Use M23 to select/reset the file, then M24 to start printing from the beginning.

Print: In this context, "print" refers to running a job on any Smoothie-controlled device such as 3D printer, laser engraver/cutter, CNC router, etc.

Format

The command is used as such:

M23 filename.gco

Which means: Select the file to be used in the subsequent M24 print/resume command.

When the file is selected, the system verifies that the file exists and is accessible on the SD card. In V2, if the file cannot be opened, an error will be returned with details about why the selection failed.

Parameters

Parameter	Usage	Example
`filename`	The file, on the SD card, will be printed in the subsequent M24 command	M20 myGcodeFile.gco

Filename Support

The filename parameter identifies the file to be used by subsequent M24 commands.

Smoothie supports both long filenames and 8.3 format.

Example

If your SD card contents were:

config.txt
firmware.cur
Readme.txt
myGcode.gco

This means if you command:

M23 myGcode.gco

The file myGcode.gco would be queued for subsequent printing with the M24 command.

To actually start printing, you would then issue:

M24

Configuration

The M23 command requires no special configuration settings.

The SD card must be properly inserted and contain the file you’re trying to select.

Macro Files Integration

When using M23 to select and M24 to start files, the Player module will automatically execute macro files if they exist:

resume.g: Executed when resuming a paused print (via M24 after pause). Useful for extruder priming or other resume procedures.
suspend.g: May be executed during suspend operations for custom handling.

Place these macro files in the root directory of the SD card if you want to use them.