If anyone interested, a DSlogic log from a working and non working interface attached from the mainboard - PIC communication.
Interface was a "lite" version initially, with transistors instead of HCPL couplers - was working but not really stable. Lexia 7.83 killed it (was onlione for a short time)
Fixed by soldering the HCPL optocoplers, replacing PIC and flashing the "C" serialnumber - plus resoldering the board.
Now stable
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