First, the converter / relay module 
 1. EDAM-8510 Isolated RS-422/485 Repeater 
 Isolation voltage 3000VDC 
 A variety of transfer rates up to 115.2 Kbps 
 Most as far as 1,200 meters transmission distance 
 Data flow LED display 
 2. EDAM-8520A RS-232 to RS-422/485 isolated converter 
 Isolation voltage 3000VDC 
 Automatic Data Flow Control 
 Adaptive transmission rate, up to 115.2 Kbps 
 Most as far as 1,200 meters transmission distance 
 Data flow LED display 
 3. EDAM-8531 Isolated USB to RS-232/422/485 Converter 
 Isolation voltage 3000VDC 
 Support USB 1.1 
 RS-485 automatic data flow control 
 USB to RS-232/RS-422 or RS-485 automatic switch (jumper) 
 Adaptive transmission rate, up to 115.2 Kbps 
 LED display working status 
 Support Windows 95/98/ME/200