What is the difference between DTR/DSR and RTS/CTS flow control?

Question

What\'s the difference between DTR/DSR and RTS/CTS hardware flow control? When is each one used? Why do we need more than one kind of hardware flow control? :)

Answer 1

The difference between them is that they use different pins. Seriously, that's it. The reason they both exist is that RTS/CTS wasn't supposed to ever be a flow control mechanism, originally; it was for half-duplex modems to coordinate who was sending and who was receiving. RTS and CTS got misused for flow control so often that it became standard.