TRENDnet RS232 to RS422 RS485 Converter Adapter, Serial Port Data Converter, Black, TI-S100 - Walmart.com
RS-232 to 2-Wire RS-485 Converter, Isolated, DIN Rail Mounted – Microflex
Amazon.com: JUXINICE 2Packs DB9 Serial Adapters No Soldering Needed. D-SUB 9-pin RS232 RS485 Adapter to Terminal Connector Signal Module with Bolts Nuts and Screwdriver (1PCS Male+1PCS Female) : Electronics