The the voltage supply of PCB is 8V-16V, at the beginning, the LIN BUS is in normal mode and LIN communication is in normal, LIN BUS / TXD / RXD waveforms are in normal LIN communication state monitored by a oscilloscope, but TXD changes to 5V and RXD changes to 0V immediately after R2 1K ohm connected between LIN BUS and Ground, the voltage of LIN BUS changes to recessive level at the same time, after removed the 1K connection to LIN BUS, LIN BUS / TXD / RXD waveforms change back to normal LIN communication state immediately;
iI 1K ohm is replaced by 2.7K ohm or 20K ohm to do the same operation, TXD doesn't change to 5V and RXD doesn't change to 0V, LIN BUS / TXD / RXD waveforms are still in normal LIN communication state, just the voltage of LIN BUS is reduced about 10%;
Why TXD changes to 5V and RXD changes to 0V mmediately after 1K ohm connected between LIN BUS and Ground? and this doesn't happen with 2.7K or 20K?
