9-pin Serial Port Cable RS232 Male-Male 1.5 Meter (DB9/COM Cable)
9-pin Serial Port Cable RS232
Serial Port RS232 Cable
Color Classification: Light Grey
DB9 male connectors on each end
At one time, RS-232 / EIA-232 was the most widely used communication standard on the planet.
It was defined and redefined many times. The “EIA” stands for “Electronic Industries Association” and the “RS” stands for “Recommended Standard.” That being the case, it was always rather loose.
The physical characteristics of the hardware include both a 25 pin and 9 pin D sub connector. RS-232 is capable of operating at data rates up to 20 Kbps and can push data about 50 ft. The absolute maximum data rate is difficult to nail down due the differences in the transmission line and cable length.
It is possible to operate at some pretty high data rates if the distance is short. The voltage levels are defined as a range from -12 to +12 volts. RS-232 is also single ended.
This means that a single electrical signal is compared to a common signal (ground) to determine binary logic states. A voltage of +12 volts (usually +3 to +10 volts) represents a binary 0 and -12 volts (-3 to -10 volts) is a binary 1. Also, RS-232 is an asynchronous serial protocol. This implies that the data word is transmitted as single bits to the receiver, which puts the word back together.
To make this happen correctly, the data rate, hand shaking, start & stop bits, and error checking must all be pre-defined. RS-232 is also an unbalanced protocol. It uses a single conductor for each signal and a common ground. The signal level is relative to the common ground. This method is cheap and easy.