I'm designing a PCB that should work as a DMX receiver and/or DMX driver (controller). I pretty much followed this schematic, with the only exception that I didn't want to use the Tx and Rx pins of the arduino, because I need those to interface with another arduino. So I use pins 11 and 12.
The guy who made that pcb also made his own library, I'm using the DMXsimplle library at the moment (I'm only going to use it as a controller for now). The PCB is not yet made, since I want to be sure it's 100% ok (high cost), so I can't test my theories.
Now my problem: I've used 6N137 optocouplers to isolate the DMX signal. Seeing the schematic, I think the output of the optocoupler goes low when the input is high and vice versa. Is this right? The datasheet also says something like that I think. Would that mean that I need to switch every bit (HIGH to LOW and LOW to HIGH) I send out from the arduino, so the DMX signal matches the sent out serial data? Or is that something the DMX library does automatically?
PCB schematic: http://www.mathertel.de/Arduino/DMXShield.aspx Datasheet optocoupler: https://datasheet.lcsc.com/szlcsc/1912111437_Everlight-Elec-6N137S1-TA_C110020.pdf