SN65HVD78: Receiver line error

Alikaan,

Is it possible to share the A and B waveforms as well?

Regards,

Eric Hackett 

Hi,

Please check below.

Hi,

Removed chip picture is attached as below

Also I assembled another chip, check the marking differences please. 8CK COEX marked one is working normally.

A (pin 6) should be the noninverting I/O (and the signal is correctly labelled in the schematic). Please check that the A/B labels are correct.

With A and B exchanged, the RX waveform is correct.
What are the two signals shown in the question?

(The receiver looks at the differential input voltage, so it might be helpful to let the oscilloscope compute A−B.)

Hi,

First screen shoots from UART TX and RX lines. I'll post the A-B line measurement asap.

The transceiver converts between logic signals and RS-485 signals. In order to find out what is wrong, you have to show both (as in your last waveform). Please ensure that the wrong RX signal is visible.

Hi, please check the following. By the way, I replaced the transceiver with one marked 8CK COEX, and it is now working properly. However, the A-B signals are the same as before.

Please check the markings also. 

The A/B signals look correct.

The slow edge shows that the R output is disabled; this happens only when /RE is pulled high. Please show the /RE voltage. (If the /RE signals has correct logic level, then different SN65HVD78 devices should not behave differently.)