Pmod RS485 polarity question

[pmod]

I'm trying to the Pmod RS485 as a RS-422 interface. In your datasheet, you reference 4 ports. A-input and B-input, which I assume is the Rx; and Y-output and Z-output, which I assume is the Tx. Do you specify which terminal is positive and which one is negative or does it not matter? I appreciate any support you can provide. Thanks.

[D@n]

@pmod,

Yeah, the spec for the analog devices part is kind of confusing, now, isn't it?  Still, confusing though it is, you can find your answer on pages 1 and 7.  On page 1, you can see that the Y and Z outputs of the device are the transmit side, whereas the A and B inputs are on the receive side.  Moving deeper into the spec, you'll find that A and Y are "non-inverting" (i.e. positive terminals), whereas B and Z are the inverting (i.e. negative) rails.  Further, if you look into the wikipedia article for RS485, you'll find this is the common nomenclature for RS485 signals.

Dan