Adding heated build plate Gcodes to firmware

Maybe this isn't the best forum for this question, but with so many to chose from I wasn't sure which one I should use. Sorry if I have guessed wrong.

I am using Tonokip's firmware for an arduino mega. It seems to be missing some Gcodes. For example, I added M126 and M127 for controlling a servo driven shut-off valve. I have now built a heated build plate and need to control it. I can hard-code it to run at one specific temperature, but a more elegant and long term solution would be better. I'm confused about the standard practice for build plate Gcode though. I want to maintain compatibility with skeinforge and repsnapper/reprap host software, which probably means I need to stick to whatever the community normally uses.

I found this Gcode list, but the only thing it really mentions temperature wise is that M104/M109 set the current extruder temperature.

I use this with the makerbot:

M104 S225.0 T0			(barrel temp to 225 DEG C)
M109 S110.0 T0			(Build plate to 110 DEG C)

While I can edit Tonokip's firmware to work like that, it isn't clear to me why T0 in one instance represents the HBP and T0 in another represents the extruder or if the reprap tool chain is even set up to use the same Gcode in the same manner.

M109 is used to pause until the barrel reaches the specified temp.

I use M109 right after my extruder goes over the purge hole. Then I extrude a little bit and start printing. It seems to make the first layer have a more consistent infill because PLA leaks out of the barrel as it heats up.

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-Steve

Maybe I didn't phrase the question quite right. I saw in the Gcode list that M104 just sets the temperature and lets Gcode parsing continue while the temperature is rampped up whereas M109 is supposed to pause until it reaches the temperature.

My question is more along the lines of how these codes are supposed to set the build plate temperature. I know what Gcode lines work with the makerbot, but I don't get how the firmware knows the difference. In the example I showed (which is known to work with the makerbot), T0 is used in both lines and the only difference between M109 and M104 is supposed to be the pause, yet in one instance it sets the build plate temperature and in the other it sets the extruder temperature.

I'm trying to understand what makes the difference so that the firmware will correctly determine if the temperature change is intended for the build plate or the extruder. I could easily make up my own Gcode command, but then Skeinforge and other parts of the reprap tool chain probably won't be able to use it and I'll have to manually add in the Gcode - bleh. I would almost prefer hard coding the temperature over manually editing every file.

dazed.dnc Wrote:
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> My question is more along the lines of how these
> codes are supposed to set the build plate
> temperature.

M140 does that.

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-Steve

See the Mendel User Manual: RepRapGCodes wiki page.

# 4 Individual commands

    * 4.1 Checking
          o 4.1.1 N and *
    * 4.2 Buffered G Commands
          o 4.2.1 G0: Rapid move
          o 4.2.2 G1: Controlled move
          o 4.2.3 G28: Move to Origin
    * 4.3 Unbuffered G commands
          o 4.3.1 G4: Dwell
          o 4.3.2 G20: Set Units to Inches
          o 4.3.3 G21: Set Units to Millimeters
          o 4.3.4 G90: Set to Absolute Positioning
          o 4.3.5 G91: Set to Relative Positioning
          o 4.3.6 G92: Set Position
    * 4.4 Unbuffered M and T commands
          o 4.4.1 M0: Stop
          o 4.4.2 M104: Set Extruder Temperature (Fast)
          o 4.4.3 M105: Get Extruder Temperature
          o 4.4.4 M106: Fan On
          o 4.4.5 M107: Fan Off
          o 4.4.6 M108: Set Extruder Speed
          o 4.4.7 M109: Set Extruder Temperature
          o 4.4.8 M110: Set Current Line Number
          o 4.4.9 M111: Set Debug Level
          o 4.4.10 M112: Emergency Stop
          o 4.4.11 M113: Set Extruder PWM
          o 4.4.12 M114: Get Current Position
          o 4.4.13 M115: Get Firmware Version and Capabilities
          o 4.4.14 M116: Wait
          o 4.4.15 M117: Get Zero Position
          o 4.4.16 M126: Open Valve
          o 4.4.17 M127: Close Valve
          o 4.4.18 M140: Bed Temperature (Fast)
          o 4.4.19 M141: Chamber Temperature (Fast)
          o 4.4.20 M142: Holding Pressure
          o 4.4.21 T: Select Tool
    * 4.5 RepRap G-Code Summary Table

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Aha!
I saw that list, but I skipped right past M140.
Sorry for being such a dolt, and thanks for helping.