RS-232 is quite famous term in telecommunications, RS-232 stands for Recommended Standard 232. RS-232 is a standard used for serial binary data signals which connects DCE (Data Circuit-terminating Equipment) to DTE (Data Terminal Equipment), most commonly used in my today’s horoscope computer serial ports. In today’s computers RS-232 is replaced with USB for local communications. RS-232 is slower than USB. USB is simple to use with its easy connectors and also it use very less energy. RS-232 and USB both have software support for all the famous operating systems. USB make it easy for device drivers to communicate with hardware, but there is no provision for direct analog to the terminal programs used which will allow users communicate directly with serial ports. Because of a protocol for transferring data to device USB is more complex than RS-232. This includes an extra software to support protocol to be used. RS-232 on the other hand only regulate voltage of signals and the functions of the physical interface pins. Nowadays application of RS 232 is gone beyond the original use of connect a terminal with modem and its successors are showing some disadvantages. Few of the limitations associated with RS 232 are:

• Noise immunity and transmission distance are limited because of the single ended signaling
• Power consumptions are increased because of large voltage swings for positive and negative supplies. Upper speed of a compatible interface is also gets limited due to the voltage swing.
• There is no specific method of sending power to device, RS232 is only suitable for low power devices like mice.
• Between two devices multi-drop connection is not defined. When multi drop works it still lacks in compatibility and speed.
• Assignment of the role of newly developed device becomes problematic because of the asymmetrical definition of the two ends of the link.