TinyG Command Line

Alden Hart edited this page Mar 18, 2017 · 21 revisions

This page describes what you can do from the command line in TinyG. Basically, it's entering configuration values and commands, and sending lines of Gcode.

Text Mode and JSON Mode

TinyG can operate in either text mode (command line mode) or JSON mode. In text mode TinyG accepts $ config lines and normal Gcode blocks, and returns responses as human-friendly ASCII text. Example:

Command Description
$xvm View X axis maximum velocity
$xvm=16000 Set X axis maximum velocity

TinyG can also operate using JSON commands. This is the preferred way to drive TinyG from a UI or controller. Using JSON dramatically simplifies the UI as the board can be treated as a RESTful resource, and no parsers or special handlers need to be written. Example:

Command Description
{"xvm":""} View X axis maximum velocity
{"xvm":16000} Set X axis maximum velocity

See JSON Operation and JSON Details.

Startup Modes

TinyG starts up in text mode if the $ej setting is set to text mode ($ej=0). TinyG will also enter text mode automatically if it receives a line with a leading $, ? or 'h'. (Note: The initial status messages returned on bootup will be in JSON format, regardless of the mode set).

TinyG starts up in JSON mode if the $ej setting is set to JSON mode ($ej=1). TinyG will also enter JSON mode automatically if it receives a line starting with an open curly '{'. While in JSON mode all commands are expected in JSON format and responses are returned in JSON format....

...the exception being Gcode blocks. Gcode blocks streamed to TinyG while in JSON mode can be sent with or without JSON wrappers - i.e. unwrapped Gcode will not return the system to text mode. Responses will always be returned in JSON format.

The rest of this page covers things that are common to both text and JSON operation.

Names and Tokens

Names are short mnemonic tokens that can be 1 to 5 characters in length. Axis and motor tokens are typically 3 characters including their axis or motor prefix; Non-axis and non-motor (general) tokens are 2 to 5 characters.

Tokens are case insensitive and can only contain alphanumeric characters. See TinyG Configuration for a complete list of the tokens used for settings. Some examples are provided below:

Token as Text as JSON Description
xfr $xfr {"xfr":""} X axis maximum feed rate
cjm $cjm {"cjm":""} C axis maximum jerk
1mi $1mi {"1mi":""} Motor 1 microstep setting
home $home {"home":""} Homing state
x $x {"x":""} X axis group. In text mode a group can only be queried (get). In JSON mode a group can be queried and can also be used to set any or all values in the group


A group is a collection of related tokens. Groups are used to specify all parameters for a motor, an axis, a PWM channel, or other logical grouping. A group is similar in concept to a RESTful resource or composite. Groups simplify configuration management and reporting by collecting related values together. The following groups are defined. All parameters within the groups are persistent (stored in EEPROM) unless noted.

Group Tokens Notes
axis x y x a b c Contain all settings for that axis
motor 1 2 3 4 Contain all settings for that motor
pwm p1 Contain all settings for pulse width modulation channel
offsets g54 g55 g56 g57 g58 g59 Contain offset settings xyzabc in named coordinate system.
temp offset g92 Contain g92 offset settings. These are not persistent
return to home values g28, g30 Contain return values in machine coordinates. These are not persistent
pos x y x a b c current work position, with offsets
mpo x y x a b c current machine position, no offsets, and always reports in millimeters
ofs x y x a b c current offsets, always reports in millimeters
hom x y x a b c e axis homing stateus. 'e' reports homing status for Entire machine
system sys Contain system parameters

To list a group type in the group prefix; for example:

  • type $x to list the X group
  • type $sys to list the system group (or simply $, which is shorthand)
  • type $g55 to list the xyzabc offsets in the G55 coordinate system


In text mode (but not JSON mode) the following groups of groups are also available for display:

Uber-Group Token Notes
axis q All axis settings for all axes
motor m All settings for all motors
offsets o All offset settings including g92's
all $ All settings. Invoked as $$

For example type $q to list all axis groups. The list of uber-groups can be seen by asking for the system help screen using $h.

Displaying Settings and Groups

When displaying or setting configs a '$' must be the first character of the line. Input is case insensitive.

A note about units Settings can be displayed and entered in either inches or millimeters. All values entered and responses provided will be in the current Gcode UNITS setting: G20 for inches or G21 for mm. Most of the examples below are in mm, but could just as easily be input in inches.

To display a setting type $<the-mnemonic-for-the=setting-you-want-to-display>. It will respond with the value taken. For example:

Request Response Notes
$xvm [xvm] x_velocity_maximum 16000.000 mm/min Show X axis maximum velocity
$3po [3po] m3_polarity 0 [0,1] Show motor 3 polarity
$ex [ex] enable_xon_xoff 1 [0,1] Show XON/XOFF setting

The following commands will display groups.

$x    --- Show all X axis settings ---
[xam] x axis mode                 1 [standard]
[xvm] x velocity maximum      16000.000 mm/min
[xfr] x feedrate maximum      16000.000 mm/min
[xtm] x travel maximum          300.000 mm
[xjm] x jerk maximum     5000000000 mm/min^3
[xjh] x jerk homing     10000000000 mm/min^3
[xjd] x junction deviation        0.0100 mm (larger is faster)
[xsn] x switch min                1 [0=off,1=homing,2=limit,3=limit+homing]
[xsx] x switch max                0 [0=off,1=homing,2=limit,3=limit+homing]
[xsv] x search velocity        3000.000 mm/min
[xlv] x latch velocity          100.000 mm/min
[xlb] x latch backoff            20.000 mm
[xzb] x zero backoff              3.000 mm
tinyg [mm] ok> 
$x    --- Show all X axis settings in inches mode (issue g20 beforehand) ---
[xam] x axis mode                 1 [standard]
[xvm] x velocity maximum        629.921 in/min
[xfr] x feedrate maximum        629.921 in/min
[xtm] x travel maximum           11.811 in
[xjm] x jerk maximum      196850400 in/min^3
[xjh] x jerk homing       393700800 in/min^3
[xjd] x junction deviation        0.0004 in (larger is faster)
[xsn] x switch min                1 [0=off,1=homing,2=limit,3=limit+homing]
[xsx] x switch max                0 [0=off,1=homing,2=limit,3=limit+homing]
[xsv] x search velocity         118.110 in/min
[xlv] x latch velocity            3.937 in/min
[xlb] x latch backoff             0.787 in
[xzb] x zero backoff              0.118 in
$3    --- Show all motor 3 settings ---
[3ma] m3 map to axis              2 [0=X,1=Y,2=Z...]
[3sa] m3 step angle               1.800 deg
[3tr] m3 travel per revolution    1.250 mm
[3mi] m3 microsteps               4 [1,2,4,8]
[3po] m3 polarity                 1 [0=normal,1=reverse]
[3pm] m3 power management         1 [0=off,1=on]
$sys  --- Show all system settings ---
[fb]  firmware build            377.08
[fv]  firmware version            0.95
[hv]  hardware version            7.00
[id]  TinyG ID                    2X2660-FHZ
[ja]  junction acceleration 2000000 mm
[ct]  chordal tolerance           0.001 mm
[st]  switch type                 1 [0=NO,1=NC]
[ej]  enable json mode            0 [0=text,1=JSON]
[jv]  json verbosity              2 [0=silent,1=footer,2=messages,3=configs,4=linenum,5=verbose]
[tv]  text verbosity              1 [0=silent,1=verbose]
[qv]  queue report verbosity      0 [0=off,1=filtered,2=verbose]
[sv]  status report verbosity     1 [0=off,1=filtered,2=verbose]
[si]  status interval           250 ms
[ic]  ignore CR or LF on RX       0 [0=off,1=CR,2=LF]
[ec]  expand LF to CRLF on TX     0 [0=off,1=on]
[ee]  enable echo                 0 [0=off,1=on]
[ex]  enable xon xoff             1 [0=off,1=on]
[baud] USB baud rate              5 [1=9600,2=19200,3=38400,4=57600,5=115200,6=230400]
[gpl] default gcode plane         0 [0=G17,1=G18,2=G19]
[gun] default gcode units mode    1 [0=G20,1=G21]
[gco] default gcode coord system  1 [1-6 (G54-G59)]
[gpa] default gcode path control  2 [0=G61,1=G61.1,2=G64]
[gdi] default gcode distance mode 0 [0=G90,1=G91]

Configuration is non-moded; that is, configuration lines and Gcode blocks can be used without changing modes. However, it is not recommended to intermingle configs with Gcode blocks, as the EEPROM writes can interfere with step generation and serial transmission (interrupts). Please note: in some future release config commands that arrive during a gcode cycle may be rejected.

CAVEAT: At the current time because of various limitations of the Xmega we recommend waiting for each config command to send a response before sending the next command. This gives allows the system to persist the data to EEPROM, because during that interval the board cannot reliably receive serial input.

Updating Settings

To update a setting enter $token=value

Tokens are a mnemonic plus a group prefix (system settings have no prefix). The setting is taken and the value is echoed in a descriptive text line. No spaces are allowed. Numeric values can contain embedded commas. The following are examples of valid and invalid inputs.

Request Response Notes
$yfr=800 [yfr] y_feedrate_maximum 800.000 mm/min Set Y axis feed rate maximum to 800 mm/min
$yfr=16,000 [yfr] y_feedrate_maximum 16000.000 mm/min Set Y axis feed rate maximum to 16000 mm/min
$2po=1 [2po] m2_polarity 1 [0,1] Set motor 2 polarity
$ex=1 [ex] enable_xon_xoff 1 [0,1] Enable XON/XOFF protocol
$ted=1 error: Unrecognized command $ted Example of an error
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