EncoderCAT  Oscilloscope views of CI-V data

The traces below are from the Rx and Tx lines of the ATxmega192A3 microprocessor USART D0.

A trace from the bidirectional, single wire CI-V line would have both Tx and Rx on the same trace.

Most CI-V interfaces would show  Tx data on the Rx line because they are connected together (via buffers).

EncoderCAT uses half of an NXP PCA9600 buffer (This is a dual I2C CAT5 line driver   ....reversed)
The Tx data does not appear on the Rx line because the internally connected Tx buffer output and Rx buffer input

have voltage levels designed to prevent this from happening.

(The pull down low voltage of the Tx buffer output (0.5v) is higher than the low voltage threshold of the Rx buffer input.)

The scope screen shot above shows the sequence for IC7000 Noise reduction level changing from 9 to 8.

The yellow trace is the Tx data from EncoderCAT and the purple trace is the responses from the ic7000