A. The data pins TxD and RxD are
considered idle at the logic 1 (HIGH) level when inactive, or active when at the
logic 0 (LOW) level. Comments about these levels when RS232 is referenced often
refer to Mark and Space levels. Mark usually means inactive and Space means
active. The voltage levels represented by the terms Mark and Space are often
reversed from those above: Mark is low voltage, and Space is high
voltage.
Figure 5-1 Block
Diagram (80xxx Mode)
A. The data pins TxD and RxD are
considered idle at the logic 1 (HIGH) level when inactive, or active when at the
logic 0 (LOW) level. Comments about these levels when RS232 is referenced often
refer to Mark and Space levels. Mark usually means inactive and Space means
active. The voltage levels represented by the terms Mark and Space are often
reversed from those above: Mark is low voltage, and Space is high
voltage.