Rigol MSO4000 User Manual page 180

RIGOL
5. Error Expressions during Decoding
In I2C bus, the front part of each frame of data contains the address information
and blue patches are used to represent address ID. In the ID, "Write" is used to
represent writing address and "Read" is used to represent reading address.
Press Include R/W to select open and "R/W" will be the part of the address
value in the AddrBits.
When the ACK (ACKnowledge Character) is not met, the red error marks as
shown in the figure below will be displayed.
8-12
ACK=1
8 Protocol Decoding
MSO4000/DS4000 User's Guide