I am using 4N37 opto isolators in a USB to RS485 design. The problem is that signals going through the 4N37s come out inverted.
If I put a 74HTC14 Hex inverting Schmitt trigger between the 4n37 and the RS485 driver it would fix my inversion problem and maybe clean up the signal a bit.
OR
The 4N37 input (internal LED) is sourced by a PIC output pin. I could move the pic output to the other side of the internal LED and use it to provide ground (sink it?). That would also fix the inversion.