English: RS232 signalling as seen when probed by an actual oscilloscope (Tektronix MSO4104B) for an uppercase ASCII "K" character (0x4b) with 1 start bit (always), 8 data bits, 1 stop bit and no parity bits (8N1)
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Removing lower half of screenshot, it provides no useful information and is wrong in many ways. (Timing is very flawed, levels are unclear) The lower half of the screenshot can be replaced by a (preferably svg) timing diagram.