Pet peeve of mine: people using the wrong connector designations.
1. DB9 - The correct designation for the 9 pin D-sub connector is DE-9. The second letter designates the physical size of the connector. common sizes (with common pin counts) are DA(15), DB(25), DC(37), DD(50), and DE(9). variations on pin counts exist, including some with larger high-current or coaxial positions. source: ITT/Cannon catalog - 1969 to present. The problem is that DB-25 was a very common connector for a long time, and when the 9 pin version started coming into common usage, everybody assumed that they were also DB, not understanding what the B portion of the designator really means.
2. RJ-45 - connectors do not have RJ designations until they are wired to a particular wiring pattern as defined by the appropriate USOC (Universal Service Ordering Code). The RJ designation specifies a specific connector, wired to a specific wiring pattern, for a specific telephone service. Some connectors such as the 6 position 4 contact (6p4c), and 8 position 8 contact (8p8c) modular connectors can be wired to multiple (and incompatible) USOC specs..
For example RJ12, RJ13 and RJ14 all use the same connector, wired the same, except for the actual phone, and the equipment termination. RJ12 and RJ13 are used for 1A2 type key systems, and share the same phone wiring, but are terminated to the equipment in a different manner. RJ14 is used for 2 line POTS phones. If a phone wired for RJ12 or RJ13 is plugged into a jack wired for RJ14, the second line will be shorted when the phone goes off hook.
The networking folks love to call 8p8c connectors wired for ethernet "RJ-45", completely ignoring the fact that the USOC spec for RJ45 calls for a similar, but different connector (keyed, vs unkeyed), which is physically different from, and wired differently from ethernet. I can build a cable that fully complies with the requirements of RJ45, that will not plug into, nor have any electrical continuity with the contacts used for ethernet. It's kind of like trying to plug a 5-20P into a 6-15R, except there are more pins to choose from, and most of the time, things won't explode when you do so, although there are exceptions. (Don't plug a cable carrying a ISDN U interface into a cisco router aux port. chips tend to change from semiconductor to smoke state.)
Ethernet connectors do not have an RJ designation, despite the misuse of the RJ45 designation by the networking/computer industry.
My friend, if you have a PayPal account, I would be honored to buy you a drink. These misnomers have been causing me to beat my head against a wall for decades. "RJ45" is bad, and "RJ11" is even worse, but when I start seeing "RJ12", I want to go postal. These are wiring patterns that have NOTHING to do with the hardware itself. I already got myself kicked out of another EC forum over this issue, so I'm glad that I'm not the "bad boy" here. Thank you for popping the cork on this subject.
This rivals a "270" as being a NEMA 5-15 duplex receptacle, when in fact, it is Cooper/Eagle's part number for the device that can be configured to deliver this wiring configuration.
