SemiAutomatic tool change mode ($341=3) requires 0xA3 command before '~' cycle start

[marxmake]

Hi everyone,
I'm currently using grblHAL firmware version 20251105 on an STM32F103 board. The setup uses a USB CDC serial port, with an SD card connected, and a fixed-installed tool setter on the machine.
For the configuration: I've set Mode 3 (parameter $341=3), along with all other relevant parameters and G30. However, I'm running into some issues and hoping for your help:
When I send a tool change command via the serial port, the machine moves to the G30 coordinates as expected. But if I then send the cycle command , I immediately get <Idle......> and several "ok" responses—without the subsequent tool setting process running. Interestingly, if I send the 0xA3 byte first before sending cycle , the tool setting works normally.
When processing files from the SD card and encountering a tool change command, neither sending cycle alone nor sending 0xA3 followed by cycle via the serial port triggers the tool setting. The machine just proceeds directly with the next part of the machining process.
Could anyone help analyze what might be causing these issues? Thanks a lot for your time!

[terjeio]

You have to send 0xA3 as soon as the state changes to Tool, even when running programs off the SD card. It could be argued that this is not neccessary when $341=3, it could be done but then the controller cannot use the Tool state to indicate a tool change.

The SD card issue was due to a new event used for changing the internal controller state on 0xA3 received was not raised for programs running off the SD card, fixed now.