News for hackers. Stuff that matters.

A comment on Homebrew USB DMX Interface with Sparkfun FT232RL. Parent comment

Re:Homebrew USB DMX Interface with Sparkfun FT232RL by stonegray on Wednesday August 03, 2022 @10:50AM (#32332535)
This existing design perfectly fine for a DMX transmitter. Unlike receivers, DMX-512 transmitters are not isolated. The isolation required in receivers will protect the transmitter from the condition you described.

EIA-485 specifies the electrical properties of the signal, however the ESTA E1.11 (DMX-512) specification further constrains it in section 5 and 6 in regards to grounding and isolation.

Annex A of the specification does provide allowance for non-isolated transmitters where common-mode voltage is expected, but this is specifically not recommended:

https://tsp.esta.org/tsp/documents/docs/ANSI-ESTA_E1-11_2008...

[ Parent | on HN ]
Re:Homebrew USB DMX Interface with Sparkfun FT232RL by loansindi on Thursday August 04, 2022 @01:35PM (#32345861)
You'd be surprised what kind of terrible things can happen on a run of DMX cable. I've seen enough transceivers exploded out of their sockets to be wary. The leading US manufacturer of lighting controls continues to use socketed DIP rs-485 transceivers exactly because they tend to take hits and fail.
[ Parent | on HN ]