August 1, 2012

USB to Serial Conversion

USB to Serial conversion

In early days of computer evolution, it had become necessary to have some kind of communication with outside world. This need was answered with a LSI chip called UART (Universal Asynchronous Receiver/Transmitter ). This, later on was made a compulsory part of every Personal Computer. It is better known as Serial Port. Information was passed on to the outside world through passing Bits serially. That is the reason why this port is also known as Serial Port. This type communication was later on standardized which is known as RS232 standard. Because of this, Serial Port is also known as RS232 port.

Based on this serial port, many other equipments like Automation Systems, Medical Systems, Industrial Controllers were developed which used to communicate with computer for further processing or presentation of the data.

With the advent of more sophisticated equipments there has been need to have more faster & less bulky alternative to this RS232 port. This need was answered in the form of USB ( Universal Serial Bus). Nowadays, this USB port has almost replaced RS232 port in desktop & laptop computers. This is ok as far as latest computers are concerned but what about the equipments that are still depending upon RS232 port to communicate to computers? This need required a kind of interpreter which converted RS232 standard to USB & vice-verse.

Welcome to Usb to Serial or USB to RS232 converters. This chips basically emulates RS232 port while it is connected to USB port. Amazing isn’t it ? Confusing ? Let us understand in detail.

This type of converter is a chip which has got USB & RS232 port built in it. It connects with computer via USB port. But the software running in the chip emulates RS232 port. So the OS (operating system) in Laptop or computer will recognize that port as RS232 port instead of USB port. It will enumerate it – declares that port as serial COM port. This is also known as Virtual COM port or VCOM or Vcom. This is called as Virtual, as if you see, physically there is no serial port but it is recognized as RS232 port and behaves like that. It virtually behaves as serial port.

Though USB communication is a bit complex to understand but because of software that resides into the chip, user does not have to worry about the complexity of USB communication.

This USB to serial converter is very useful where there is no physical RS232 port or COM port is available & you want to communicate with a system where only RS232 port is available. This converter presents itself to computer as if it is a COM port. It’s behavior is as good as a “real” COM port. All the data lines available to 9 pin actual COM port are brought out as a real port.

The software inside the converter not only emulates itself as a COM port but it also interprets the data from one standard- USB – to other that is RS232 standard.

Life becomes easy for a computer operator and also it provides lease of life to many equipments & devices that are still dependent upon legacy RS232 port for communication.

Fortunately we have also U452-USB based Data Acquisition Card, which emulates itself as a Virtual COM Port. This makes it very easy to communicate & play with the card.

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