DMX signal not working after adding optoisolator

Thread Starter


Joined Oct 31, 2009
Hello. I'm working on a custom DMX device and am in the process of learning how to read a DMX signal with an ESP32. I started out with a MAX3485 chip and was able to successfully read DMX data on an ESP32. Super! Now I'm trying to add an optoisolator into the circuit but so far I'm not having any luck. Note: Right now I do Not actually have a DC/DC (such as RFB-0505) power isolator on my bread board so power is not truly isolated yet, but that is full the plan.

Does it look like I've wired the optoisolator correctly?
Can I still properly test with an optoisolator in the circuit even if I'm not actually using a DC/DC power isolator yet?

Attached is my circuit before and after adding the optoisolator. Thank you for having a look.