horace, thanks so much for the link. It cleared up a lot of my confusion over the Max485 pin functions.
markd833, thanks so much for pointing out that I had Nano D3 connected to the wrong pin on the Max485. Also thank you for the note about tying to 5v to keep it on transmit.
Unfortunately, it's still not working.
I checked the voltage of A and B on the max485 and they're fluctuating between:
A= +2.90 to +2.92
B= +1.39 to +1.41
VCC is at 4.53
Not sure what else I'm missing here.
Also one more thing I noticed... if I disconnect one of the 2 data pins from the max485 (A or B) to the DMX cable, the light starts flashing all kinds of colors randomly. and the lighting fixture's 'dmx signal' indicator is flashing erratically.
I'm not sure if that makes any difference in troubleshooting this problem I'm having, but wanted to mention in case that gives any clues