here are some pics of the unit and its parts, if anyone is interested in a unit let me know, i can let you know how to get it
I hope you would not give the same shop name for others. Have you opened the multiplexer to see how it looks (I can send you photos if you don't want to open it)?
Have you opened the small box at the PC-cable where the RS232 to RS485 label is for? What do you think it tells about a product if it has an empty box, why do they do that?
Remember to come back and report when it stops working.