9 PIN D-SUB FEMALE to Computer
The Norton Diagnostics serial loopback plug is a 9-pin female DE-9 connector designed to mate directly with the male DE-9 serial port on a PC rear panel. It allows diagnostic software — specifically Norton Utilities: Norton Diagnostics from Symantec — to verify UART hardware by looping transmit signals back to the corresponding receive inputs. The DE-9 serial connector was standardised under TIA-574 and introduced on the IBM PC/AT in 1984, with the governing electrical standard being ANSI/TIA/EIA-232-F (RS-232). The Norton variant extends the common loopback wiring by including the Ring Indicator (RI) signal on pin 9, enabling testing of all major RS-232 modem-control lines.
| Name | Pin | Pin | Pin | Pin |
|---|---|---|---|---|
| Jumpering 1 | 2 | 3 | ||
| Jumpering 2 | 7 | 8 | ||
| Jumpering 3 | 1 | 4 | 6 | 9 |
Signals
- Jumpering 1 — connects RxD (pin 2) to TxD (pin 3), looping received data back to the transmit output for UART self-test
- Jumpering 2 — connects RTS (pin 7) to CTS (pin 8), looping the request-to-send handshake signal back to clear-to-send
- Jumpering 3 — connects DCD (pin 1), DTR (pin 4), DSR (pin 6), and RI (pin 9) together, looping all modem-control and ring-indicator lines as a group
Notes
- The plug connects to the male DE-9 serial port on the PC; no cabling is required.
- The inclusion of RI (pin 9) distinguishes the Norton wiring from some other diagnostic loopback plugs (such as PassMark PM012) which omit the Ring Indicator line.
- Loopback connectors must be wired correctly and seated firmly for serial port tests to pass.
References
- Serial and Parallel Port External Loopback Wiring Diagrams — PC-Doctor, Inc.
- SunVTS 6.2 Test Reference Manual for x86 Platforms — Appendix A: Loopback Connectors — Oracle Corporation (Sun Microsystems)
- SunVTS 3.0 Test Reference Manual — Appendix A: Loopback Connectors — Oracle Corporation (Sun Microsystems)