Tech Stuff - RS232 Cables and Wiring DB9 (EIA/TIA 574): View - looking into male connector (male and female connector diagrams) RS232 on RJ45 (RS-232D) More properly EIA/TIA - 561. Use when connecting to or from a serial port with a 8 position Modular Jack (RJ45). If you are cross-connecting from a DB9 or a DB25 use the signal names to cross connect the appropriate pins. Easy RJ45 Wiring (with RJ45 pinout diagram, steps and RJ45 pinout diagram for standard T568B, T568A and crossover cable are shown here! To remember the RJ45 wiring order we created tools that make it easy to memorize. We give more; the complete Ethernet pinout cable wiring reference with wiring step-by-step guide. DB9 Pinout D-sub 9 Connector Pinout . Pinout and diagram of DE9 connector (DB9 connector), commonly used for serial ports (RS-232). RS232 Cables and Wiring - Shrubbery So a DB9 is more properly a DE-9P. Isn't knowledge a wonderful thing! up. T1/E1 Pinout (RJ-48C) T1/E1 wiring may use either a RJ45, DB15 or BNC connectors. The pinout shown uses RJ45 connectors and is known as USOC RJ-48C. T1 is a North America (primarily) digital service providing 1 Mbps.