grbl-LPC-CoreXY/doc/markdown/change_summary.md

Grbl v1.1 - Change Summary

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Specific details are available in the interface.md document.

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GUI Interface Tweaks from Grbl v0.9

Grbl v1.1's interface protocol has been tweaked in the attempt to make GUI development cleaner, clearer, and hopefully easier. All messages are designed to be deterministic without needing to know the context of the message. Each can be inferred to a much greater degree than before just by the message type, which are all listed below.

• ok / error:x : Normal send command and execution response acknowledgement. Used for streaming.

• < > : Enclosed chevrons contains status report data.

• Grbl X.Xx ['$' for help] : Welcome message indicates initialization.

• ALARM:x : Indicates an alarm has been thrown. Grbl is now in an alarm state.

• $x=val and $Nx=line indicate a settings printout from a $ and $N user query, respectively.

• [MSG:] : Indicates a non-queried feedback message.

• [GC:] : Indicates a queried $G g-code state message.

• [HLP:] : Indicates the help message.

• [G54:], [G55:], [G56:], [G57:], [G58:], [G59:], [G28:], [G30:], [G92:], [TLO:], and [PRB:] messages indicate the parameter data printout from a $# user query.

• [VER:] : Indicates build info and string from a $I user query.

• [echo:] : Indicates an automated line echo from a pre-parsed string prior to g-code parsing. Enabled by config.h option.

• >G54G20:ok : The open chevron indicates startup line execution. The :ok suffix shows it executed correctly without adding an unmatched ok response on a new line.

On a final note, this interface tweak came about out of necessity, as more data is being sent back from Grbl and it is capable of doing many more things. It's not intended to be altered again in the near future, if at all. This is likely the only and last major change to this. If you have any comments or suggestions before Grbl v1.1 goes to master, please do immediately so we can all vet the new alteration before its installed.

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Realtime Status Reports Changes from Grbl v0.9

• Intent of changes is to make parsing cleaner, reduce transmitting overhead without effecting overall Grbl performance, and add more feedback data, which includes three new override values and real-time velocity.

• Data fields are separated by | pipe delimiters, rather than , commas that were used to separate data values. This should help with parsing.

• The ability to mask and add/remove data fields from status reports via the $10 status report mask setting has been disabled. Only selecting MPos: or WPos: coordinates is allowed.

  • All available data is always sent to standardize the reports across all GUIs.
  • For unique situations, data fields can be removed by config.h macros, but it is highly recommended to not alter these.

• MPos: OR WPos: are always included in a report, but not BOTH at the same time.

  • This reduces transmit overhead tremendously by removing upwards to 40 characters.
  • WCO:0.000,10.000,2.500 A current work coordinate offset is now sent to easily convert between position vectors, where WPos = MPos - WCO for each axis.
    • WCO: is included immediately whenever a WCO: value changes or intermittently after every X status reports as a refresh. Refresh rates can dynamically vary from 10 to 30 (configurable) reports depending on what Grbl is doing.
    • WCO: is simply the sum of the work coordinate system, G92, and G43.1 tool length offsets.
    • Basically, a GUI just needs to retain the last WCO: and apply the equation to get the other position vector.
    • WCO: messages may only be disabled via a config.h compile-option, if a GUI wants to handle the work position calculations on its own to free up more transmit bandwidth.
  • Be aware of the following issue regarding WPos:.
    • In Grbl v0.9 and prior, there is an old outstanding bug where the WPos: work position reported may not correlate to what is executing, because WPos: is based on the g-code parser state, which can be several motions behind. Grbl v1.1 now forces the planner buffer to empty, sync, and stops motion whenever there is a command that alters the work coordinate offsets G10,G43.1,G92,G54-59. This is the simplest way to ensure WPos: is always correct. Fortunately, it's exceedingly rare that any of these commands are used need continuous motions through them.
    • A compile-time option is available to disable the planner sync and forced stop, but, if used, it's up to the GUI to handle this position correlation issue.

• The Hold and Door states includes useful sub-state info via a : colon delimiter and an integer value. See descriptions for details.

• Limit and other input pin reports have significantly changed to reduce transmit overhead.

  • The data type description is now just Pn:, rather than Lim:000 or Pin:000|0|0000
  • It does not appear if no inputs are detected as triggered.
  • If an input is triggered, Pn: will be followed by a letter or set of letters of every triggered input pin. XYZPDHRS for the XYZ-axes limits, Probe, Door, Hold, soft-Reset, cycle Start pins, respectively.
  • For example, a triggered Z-limit and probe pin would report Pn:ZP.

• Buffer data (planner and serial RX) reports have been tweaked and combined.

  • Bf:15,128. The first value is the available blocks in the planner buffer and the second is available bytes in the serial RX buffer.
  • Note that this is different than before, where it reported blocks/bytes "in-use", rather than "available". This change does not require a GUI to know how many blocks/bytes Grbl has been compiled with, which can be substantially different on a Grbl-Mega build.

• Override reports are intermittent since they don't change often once set.

  • Overrides are included in every 10 or 20 status reports (configurable) depending on what Grbl is doing or, if an override value or toggle state changes, automatically in the next report.
  • There are two override fields:
    • Ov:100,100,100 Organized as feed, rapid, and spindle speed overrides in percent.
    • T:SFM with each letter S, F, and M are defined as spindle stop active, flood coolant toggled, and mist coolant toggled, respectively.

• Line numbers, when enabled in config.h, are omitted when:

  • No line number is passed to Grbl in a block.
  • Grbl is performing a system motion like homing, jogging, or parking.
  • Grbl is executing g-code block that does not contain a motion, like G20G54 or G4P1 dwell. (NOTE: Looking to fixing this later.)

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