Network Serial Port Kit User Manual - Using Different Null-Modem Schemes
Null modem - Wikiwand
Should I Use Null Modem or Straight Through Serial Cables? - NI
18663: Null Modem Cable, 9-Pin Male to 9-Pin Male
Null Modem & Crossover Ethernet Pin Outs
FTDI Chipset Cross Wired USB Serial DB9 FT232R USB RS232 Cable de módem nulo Cable de TV de control (estándar DB9 COM puerto pinout (pc(host) con USB a RS232 dispositivo terminal (esclavo)) :
VK-2D13 Product Manual — Connecting to the Console Port | Netgate Documentation