RepRapFirmware 3.5 provides experimental support for multiple motion systems that move asynchronously with respect to each other. Each motion system has its own current tool. A single GCode job file or input stream controls all the motion systems. Additional commands in the GCode stream specify which motion system each command is destined for. Some commands (in particular M400) cause motion to be synchronised, i.e. when the command is reached the system waits for all commands for any motion system prior to that command to complete before continuing.
The primary application is to speed up printing by having the printer work on separate parts of a large print concurrently, or to print two different objects at the same time.
M595 Q1 P60 will increase it to 60 elements (the same number as in the primary movement queue on MB6HC and MB6XD boards).If running from a file (i.e. a job or macro on the SD card), use M606, by adding M606 S1 at the beginning of the file, to enable the forking of the file to each motion system queue.
Use the M596 command to specify which motion system any motion or tool operations in the following commands should be targeted at. The selection of target motion system remains in force until one of the following occurs:
Use the M597 command to set up a restriction on how close together the positions of two axes can get. For example, if you machine has separate Y and V gantries that move independently, use M597 to prevent them from coming too close together. Only one pair of axes can be restricted in this way.
There will be times when the two motion systems need to be synchronised. For example, when the two motion systems are used to drive the two print heads of a IDEXY machine independently, they will need to synchronise at each layer change because they share a common Z axis.
M400 S1 or G4 P0 to wait until all motion stops, but NOT release any owned axes and extrudersCertain other commands will also cause synchronisation (details to follow).
The way that command streams that use multiple motion systems are processed depends on the source of the command stream.
For command streams from USB, async serial input (including PanelDue) and the DWC console, the commands are processed by a single GCode processor. This means that the ability of the system to execute motion of both systems concurrently may be limited. When there is a long block of motion commands for one system, the GCode processor must queue all those commands before it can process subsequent commands that are targeted at another motion system. If there are more move commands for one motion system than will fit it the queue (bearing in mind that segmentation may turn single move commands into multiple commands) then processing of subsequent commands destined for the other motion system will be delayed.
| Single Gcode Processor | ||
|---|---|---|
| Input | Object Model input | Notes |
| Http | 0 | |
| Telnet | 1 | |
| USB | 3 | |
| Aux | 4 | UART (eg PanelDue) |
| Trigger | 5 | |
| LCD | 7 | |
| SBC | 8 | Used for codes from the SBC, e.g. dsf-config.g, http for the web interface, plugins and the CodeConsole tool. Generally behaves the same as the http channel. |
| Daemon | 9 | |
| Aux2 | 10 | UART2 |
| Autopause | 11 | |
For command streams that originate from file (i.e. job or macro on the SD card), each motion system uses a separate GCode processor to process commands targeted at that motion system, skipping commands that are targeted at other motion systems.
Note: to enable the separate command streams and Gcode processors, the file/macro should include an M606 command to fork the input file, and allow the input stream to be forked to each Gcode processor. Add M606 S1 in the job file or in the start.g.file.
The M606 command must be used in the job file if you want the second input stream to execute commands for the second movement system; otherwise commands for both movement system are executed by the primary file stream. When the job completes the secondary file stream is closed and commands in the stop.g file for both motion systems are executed by the primary stream.
There is usually a need to synchronise the motion systems at particular points in the file. For example, there may be blocks of motion commands for each motion system that can execute concurrently because each motion system operates within its own defined area, such that collisions will not occur. Subsequently it may be necessary to change these defined areas so that parts of the job that were not not accessible using the previous areas can be accessed. Or, where the motion systems share a common Z axis, it may be necessary for them to both complete the current layer of a 3D print before Z can be moved ready for the next layer.
The commands streams can be synchronised using a M598 command. Each GCode processor that reaches the M598 command will pause until all other processors have caught up.
| Multiple Gcode Processors | ||
|---|---|---|
| Input | Object Model input | Notes |
| File | 2 | First logical input. |
| File2 | 12 | Second logical input. File2 can not be used directly. |
| Queue | 6 | Queue is used for commands received from File that need to be delayed to sync with movement |
| Queue2 | 13 | Second queue for second file stream. Queue2 does the same as Queue, but for File2. Queue2 can not be used directly. |
The File and File2 channels are logically a single channel. When you start a GCode job, the job file is opened by both of them. If the job contains no commands to use the second motion system then File2 will quickly reach the end of file or the M0 command, and wait for File to catch up. The point of having two channels that are logically a single channel is so that one can get well ahead of the other. Whereas if you send commands for both motion systems through one of the other channels, then the most that one channel can get ahead of the other is limited by the length of the movement queue.
All user-accessible channels default to the primary motion system, but you can use M596 to switch. So you could have a daemon.g that switches to motion system 1 and use it to do background tasks, while everything else uses motion system 0, e.g. the following example for daemon.g runs fully in the second motion system:
; NOTE: this example is for continuous motion of another axis.
; The motor is defined as an extruder instead of an axis, then a dummy tool is created that uses it.
; Then in daemon.g select that tool and send relative extrusion commands.
M606 S1 ; enable forking of the file to each motion system queue
M596 P1 ; use second motion system
T1 ; select continuous tool
G91 ; use relative extrusion
while {global.runContinuous == true}
G1 E10 F1000
G4 P500
Each input can be allocated to a motion system, and remains on that motion system until switched back. If you allocate DWC (http) or the PanelDue (Aux) to motion system 1, then all inputs from that relate only to motion system 1. (That means both those UIs need to change motion systems depending on which axes are being jogged etc)
All channels default to motion system 0 oafter start up. If you want a channel to use the second motion system, that channel must use M596 to switch it to motion system 1.
When a job file completes or executes M0/1/2, RRF waits for both motion systems to stop.
If a job file, HTTP or SBC calls a macro then both motion systems execute it; but the contained commands will generally be executed by only one of File and File2. The reason for this is that a macro may contain M596 commands, so both File and File2 need to execute it. Each will skip the commands that don't apply to it.
A few other commands lock both motion systems but they are mostly configuration commands, e.g. M569 and M569.1 when used with parameters other than just the driver number, M574 when changing axis endstops, M150 when addressing Neopixels on a bit-banged port, M563 when used to create or delete a tool, M81, etc.
Each input channel (SD card, USB, http, telnet etc) has its own set of flags. For all of the Gcode commands below, the following is true:
| Command | Description | Default flag | Notes |
|---|---|---|---|
| G1/G2/G3 (and G0 in FDM mode) | Feed rate | 3000mm/min | flag for feed rate if the next G0/1/2/3 command doesn't include an F parameter |
| G17/G18/G19 | The selected plane for arc moves | G17 (XY plane) | |
| G20/G21 | Units (inches or mm) | G21 (mm) | |
| G90/G91 | Axis absolute/relative positioning | G90 (absolute) | |
| G93/G94 | Inverse time mode/units per minute mode | G94 (units per minute) | |
| M82/83 | Extruder absolute/relative mode | M82 (absolute) | |
| M200 | Volumtric extrusion | Disabled |