Mesa UART doesnt work after update to linuxcnc2.8

PCW wrote: Is this on identical hardware/firmware as 2.7?

No i didnt test it on 2.7 version. Both version are 2.8 and built in rip mode.

I'm not clear on what has changed, have you changed OS, Firmware, or hardware?

As far as I can by the file history tell nothing major changed in the UART code recently

There is not much change, i just switch from an old 2.8 version that i download about a year ago to recent 2.8 version. Both are built in same OS, Firmware and hardware even config file.
My bug look like all data is overwrited because it's fine if i use only1 channel but if i use 2 channels, the data is stored in channel 1 come from channel 2 and channel 2 dont have any data

So I would have to agree with cmorely
It probably will require git bisect to find the
commit that broke things

Bit of a long shot but: Early in its life V 2.8 did not check for the ini file version and ask for an upgrade from V 2.7. I wonder if part of your problem is that your config was deemed to be an old version and "upgraded"?

If this has happened check the 2.8 docs about what is said about version and ensure the original version is manually updated to agree.

I dont know how to use bisect to check yet. But i tried download master version to test with halrun, this time i just use mesa_uart,modify baudrate and dont touch anything else, bug still happenned. So i think this bug happen inside recently versions