I have a similar problem. Just this morning I changed a computer. Now running the same program, with the same drivers I also get the error -33816 (Unexpected character received from Optomux response).
But I do have one big difference: Generally it works (for over 1h) and out of a sudden I get the error. Are there still the same recommendations for solving this problem or is there anything new?
Thanks in advance.
As I use RS232, this won't help. But obviously it must have been a driver based problem. The port which I used is on an extension card (4 additional com ports). As one more try I used another com port (also on the extension card). This port seems to run without any problems up to know. Yesterday was no problem and what happened over night I'm gonna check right now.
Anyway, thanks for your efforts.
We got this error in a repeatable fashion by unplugging a non-functional UPS. It id due to dropping power to the fp1000.
Hope this helps.