I'm studying connectors for the A+ exam and I'm a little confused on serial connectors. Do DB-9 and RS-232 connectors use the same protocol? Or are they different?
What's the difference between DB9 and RS-232?
That's a good question, and it is really confusing. All serial connections communicate using the same method, but there are varying configurations. The term DB-9 really pertains to the connectors on the end of the cables and not the cables themselves. DB9, for example, is a 9 pin connector for a serial cable. You can see one here.
RS-232, on the other hand, refers to the standard itself. RS-232 (sometimes called EIA-232) describes how systems can communicate between each other using a serial cable. The cable itself may be DB-9 or even DB-25.
Hope that helps,
This is something that I have been interested in for some time because I work with camera systems. They use RS-485 and RS-422 protocols for some of the comms for the PTZ cameras. Systems often use RS-232 for text overlay from ATM'S etc. In my research the RS-232/485/422 describes the electrical characteristics of the conductor paths the signal travels across. Impedance, voltage variation, resistance of the circuit and such. Hopefully someone who knows more than me could clear up some things because I still have alot of questions about this topic.
I should have been more specific. In the "computer world" the serial ports all communicate using the same method. Outside of the computer world, like in Paul's example, you can see all sorts of different communications being sent over the same connectors and cables.
On of my favorite examples is the Firewire connector. In the computer world we know it as IEEE1394 and use it for data transfers. Before that, though, the Firewire connector was used for the original Nintendo Gameboy video game system to allow people to play games against each other. It was the same connector and cable, but it did not use the Firewire protocol.
You're right about the form factors being reused RJ45 and similar is used in other applications as well.
Think about DB9 as the form factor of the connector. The physical style of it, and the pin count and stuff like that. RS232 would describe the communication used very commonly in the DB9 or DB25 connector.