RS-232 boosters double the range of your RS-232 data signal. Repeaters may be daisy-chained for extra range. Many CE computers, laptops, and some desktops ship with low-power ports that are unable to drive port-powered devices or full-length RS-232 cabling. RS-232 signal boosters amplify these weak signals up to the RS-232 standard.
Advantech
Advantech ADAM-4500 Series RS422/485 Repeater (F)
Advantech
Advantech RS-422/485 Repeater
Advantech
Advantech ADAM-4500 Series RS422/485 Repeater (extended temperature)
Advantech
Advantech ADAM-4500 Series RS422/RS-485 Repeater with Isolation (F)
Advantech
Advantech RS-422/RS-485 Repeater with Isolation