I have 3 print heads and I have MPCTEMP set up and working. Using Pronterface I can get head E0 by default, to tune using M306 T. When I try to use M306 T E1 or E2, it still goes to E0 every time. What am I missing?

I think you've run into a bug.

As I read the code, the E parameter is not used.

Try issuing a T1 or T2 command before the M306 T command and see if that gets it to tune the desired extruder.

Good call! That works. They need to redo the extensions and add this. Thanks.

Please try again using the attached file. I've added some code so the T command is automatically done when doing the autotune.

Thanks Bob. I won’t get to this until late tomorrow. I do appreciate your time.

Bob, copied file but won’t compile err at M306

Please post your config files so I can reproduce the error.

Config.h

You're using Marlin 2.1.2.

Attached is a version that compiles with 2.1.2.

I’m using bugfix 2.1.X
I tried the M306 2.1.2 and it functioned as before. Only way to change is with a T1 or T2
I did M306 E1 T and M306 E2 T and all went to E0
I tried M306 E1 and E2 went to same as M306 and M306 T1 and all went to E0

Edited 1 time(s). Last edit at 01/30/2023 10:54PM by SlickNickeL.

Current bugfix is version #define CONFIGURATION_H_VERSION 02010300

Provided Config is
#define CONFIGURATION_H_VERSION 02010200

so it may be an old bugfix, but is not current bugfix

Here's a couple more attempts at a M306 for bugfix-2.1.x. Both compile without errors.

M306_enqueue_one_now uses a different approach to enqueuing the command than my last attempt.

M306_T_code copies the code from T.cpp.

To be honest, I don't know enough about multi extruder/systems to be have confidence that either approach is a good long term solution. The best long term approach would be to open a bug report and hope one of the Marlin gurus help.

I couldn’t get either one to compile. It’s not a biggie at the moment. It works well with T1 and T2 prior to M306 T. I did notice that after a T1orT2 then M306 T, it says E0, busy, busy, busy, E1 or E2 then shows and the correct head is tested. M500 and it’s all good. M306 reports correctly to the changes.
As we get into 3 head manufacturing, this will need to addressed. I will put in a bug report.

The fix has been moved into bugfix-2.1.x as of about 8 hours ago.