I used the MAX483 chip with its Vcc connected to regulated 5V supply for my 7 clocks with a network of around 100 meters. It worked for a couple of years now. Customer expanded his firm and ordered another 7 clocks to be added to the network, 1 on the 5th floor one on the second floor and 5 on the 1st floor where the old 7 clocks are located. Looks like the trip to the 5th floor and back to 2nd floor and back to 1st floor took another 100 meters of length.
I noticed 2 of the 5 clocks at the end of line do not receive the data, I measured the amplitude of the RS422 signal and it was very low less than 0.5v. So I made RS422 repeater board for the last 5 clocks and supplied them with 5Vdc Vcc which solved the problem.
Thinking about the problem again (After it has been solved) I noticed that MAX48x chips are rated for 12Vdc supply. If I raised the Vcc of my master MAX483 chip to 12Vdc, probably I don't need the repeater board to extend the range and would have saved my self one day of work.
What Vcc supply voltage do you use for your RS485/422 applications?
Mahmood