The Cisco CAB-OCTAL-ASYNC (part 72-0845-01) is an octal asynchronous serial cable used with high-density async network modules — specifically the NM-16A and NM-32A — fitted in Cisco 2600 and 3600 series routers. The router-side connector is a male 68-pin high-density D-sub (HPDB-68, also referred to as SCSI-II or DB-68), which breaks out to eight individual RJ-45 tails, each pre-wired as a rollover cable. Each RJ-45 leg carries asynchronous RS-232 (EIA/TIA-232) signals and plugs directly into any Cisco-schema RJ-45 console port without an additional adapter; for target devices with DB-25 console ports the ‘Modem’-labelled RJ-45-to-DB-25 adapter must be used to obtain the correct DCE/DTE polarity.
68 pin hi-density D-SUB female connector
8 pin RJ45 (8P8C) male connector
| RJ-45 Plug | Pin | Signal | 68-Pin SCSI (J1) |
|---|---|---|---|
| 1 | 1 | CTS | 39 |
| 2 | DSR | 5 | |
| 3 | RXD | 38 | |
| 4 | RXD GND | 4 | |
| 5 | TXD GND | 37 | |
| 6 | TXD | 3 | |
| 7 | DTR | 36 | |
| 8 | RTS | 2 | |
| 2 | 1 | CTS | 43 |
| 2 | DSR | 9 | |
| 3 | RXD | 42 | |
| 4 | RXD GND | 8 | |
| 5 | TXD GND | 41 | |
| 6 | TXD | 7 | |
| 7 | DTR | 40 | |
| 8 | RTS | 6 | |
| 3 | 1 | CTS | 47 |
| 2 | DSR | 13 | |
| 3 | RXD | 46 | |
| 4 | RXD GND | 12 | |
| 5 | TXD GND | 45 | |
| 6 | TXD | 11 | |
| 7 | DTR | 44 | |
| 8 | RTS | 10 | |
| 4 | 1 | CTS | 51 |
| 2 | DSR | 17 | |
| 3 | RXD | 50 | |
| 4 | RXD GND | 16 | |
| 5 | TXD GND | 49 | |
| 6 | TXD | 15 | |
| 7 | DTR | 48 | |
| 8 | RTS | 14 | |
| 5 | 1 | CTS | 55 |
| 2 | DSR | 21 | |
| 3 | RXD | 54 | |
| 4 | RXD GND | 20 | |
| 5 | TXD GND | 53 | |
| 6 | TXD | 19 | |
| 7 | DTR | 52 | |
| 8 | RTS | 18 | |
| 6 | 1 | CTS | 59 |
| 2 | DSR | 25 | |
| 3 | RXD | 58 | |
| 4 | RXD GND | 24 | |
| 5 | TXD GND | 57 | |
| 6 | TXD | 23 | |
| 7 | DTR | 56 | |
| 8 | RTS | 22 | |
| 7 | 1 | CTS | 53 |
| 2 | DSR | 29 | |
| 3 | RXD | 62 | |
| 4 | RXD GND | 28 | |
| 5 | TXD GND | 61 | |
| 6 | TXD | 27 | |
| 7 | DTR | 60 | |
| 8 | RTS | 26 | |
| 8 | 1 | CTS | 67 |
| 2 | DSR | 33 | |
| 3 | RXD | 66 | |
| 4 | RXD GND | 32 | |
| 5 | TXD GND | 65 | |
| 6 | TXD | 31 | |
| 7 | DTR | 64 | |
| 8 | RTS | 30 |
Signals
- CTS — Clear To Send; flow-control input to the router async port
- DSR — Data Set Ready; modem/DCE-ready input to the router async port
- RXD — Receive Data; serial data input to the router
- RXD GND — Signal ground reference for RXD line
- TXD GND — Signal ground reference for TXD line
- TXD — Transmit Data; serial data output from the router
- DTR — Data Terminal Ready; output from the router indicating port is active
- RTS — Request To Send; flow-control output from the router
Notes
- The 68-pin connector is a male HPDB-68 (also called SCSI-II or HD-68); it is not a standard 50-pin SCSI connector.
- Each of the eight RJ-45 tails is already wired as a rollover (all eight conductors reversed end-to-end), enabling direct connection to any Cisco-schema RJ-45 console port.
- For target devices with DB-25 console ports, use the RJ-45-to-DB-25 adapter labelled ‘Modem’ — not ‘Terminal’ — to achieve the correct DTE/DCE polarity reversal.
- Default terminal settings for Cisco async ports: 9600 baud, 8 data bits, no parity, 1 stop bit, no hardware flow control.
- RJ-45 ports on the octal cable follow the standard Cisco DTE pinout: pin 1 = RTS out, 2 = DTR out, 3 = TD out, 4 = SigGnd, 5 = SigGnd, 6 = RD in, 7 = DSR in, 8 = CTS in.