Customized Prolific PL2303 USB RS232 DB9 Crossover Rollover Null Modem Cable for TV IPTV STB TV-BOX DVB Configuration - AliExpress
Null modem cable
What is the schematic of an RS232 Null-Modem? - Ferguson Wiki
StarTech.com Null-Modem Serial Cable - Extend your EGA monitor cable or mouse cable by 6ft - 6ft rs232 cable - 6ft db9 cable - 6ft db9 serial cable -6ft straight through serial