Selecting Tool 2 does not heat correct tool with multiple extruders

[turbo178]

Version

Version 2.1.1 + win64
Operating system type + version

Windows 10 Home V# 10.0.18363 Build 18363

In case of 3D rendering issues, please attach the content of menu Help -> System Info dialog
3D printer brand / version + firmware version (if known)

DBot CoreXY with RepRap Firmware V# 2.05.1

Behavior

I only want to use extruder #2 for a print, so i set all the values for extruder number to 2. when i send the print to my printer, it does not heat up the correct tool. i can see in the gcode that the heat command comes before the tool selection. i dont want to have to manually input the tool in the start code, in case i change my values in the settings. this is a multi extruder setup, (e3d chimera).
Is there any way to input a line in the extruder temp such as:
M104 S[first_layer_temperature] T[extruder_selected]

• Steps needed to reproduce the problem
  Select extruder 2 for all settings in multiple extruders tab, slice, then print. see screenshot

• Expected Results
  the Correct tool heats up, in this case tool 2

• Actual Results
  tool 1 heats up on standby and the print starts, trying to cold extrude out of tool 2

  • Screenshots from PrusaSlicer preview are preferred

[Lukrative525]

This isn't the most elegant solution, but I get around this using a G10 command like this:

G10 S[temperature_[initial_tool]] P[initial_tool]

Edit: for anyone else reading, I think this only works with RRF.

[mbordoni]

I have similar problem with prusa mk3s + mmu2s.
On filament switch the new filament temp is set before the old filament is unloaded.
This cause a bad tip on old filament (specially in case of soluble pva filament use) and frequent mmu2s hanging.
Please postpone new temp set in gcode.