RS422 flipping bits

A mark is supposed to be the lowest level while a space is the highest... the trace looks correct to me.

If you need to invert the data, a single transistor and a couple of resistors can do the job.

The letter A is 1000 0010 (least significant bit first).

So, are you say> > I suspect a device I have is flipping bits before it sends out RS422

RS-422 and RS-485 are supposed to have two outputs, A and B. A is supposed to be non-inverting, and B is supposed to be inverting. You didn't label voltages, so I'd assume you're looking at A.

If you have a straight RS422-to-RS422 connect, If you put a logic 1 (5V) into the driver, and then you connect A of the driver to A of the receiver, and B of the driver to B of the receiver, you will see a logic 1 (5V0 at the output of the receiver.

If your situation is more complex, possibly you could grant us a few more details. Still waiting on a description of whether this is an existing setup or you're cobbling something up.

Since you seems to be new to this, and you're also a Google Grouper (so am I), you should know that it's considered good form to bottom post (put your answer *under* the copy of the prior post). You should please check out Google Groups Help Topic "What's good 'netiquette' when posting to Usenet?"

Cheers Chris

Yes. Those "A" bits have been flipped.

Looks like you are using the UART on a micro to format the send characters and from the way the LSB's are being sent out first, you're also using a UART to receive them.

If so, the sending UART will be -absolutely- flipping those "A" bits. It knows only of RS232 and nothing of RS422, hence assumes it is sending data to a Max232 type inversion chip. You can see this from the UART pin being at