Generally about the Serial Port Card. Serial PCI Card / Serial PCMCIA Card.
A serial port card such as a PCI serial port card or PCMCIA serial port card is an easy and reliable way of establishing a serial RS232, RS485 or RS422 port in a computer. Usually a serial port card is used for adding a serial RS232 port in a computer which can be used for connecting a variety of serial RS232 devices, however serial port cards can also be used for creating a RS485 or RS422 port.
Typically a serial port card is either categorized as a PCIexpress serial port card (PCIe), a standard PCI serial port card, a PCMCIA serial port card, or the new standard replacing the PCMCIA serial port card called a serial ExpressCard which is smaller than the PCMCIA serial port card and is being used in all newer computers sold today.
The most commonly used serial port card is the PCMCIA serial port card or PCI serial port card, probably because these are easy to insert and start using in any desktop or laptop computer with a standard PCMCIA port slot or standard PCI card slot. However the new ExpressCard serial port card mentioned earlier is taking over.
After the PCMCIA serial port card, the PCI serial port card is the next most popular type of serial port card. The PCI serial port card is a bit harder to install than the a standard PCMCIA serial port card, since this type of serial port card requires you to physically open up your desktop computer and install the card in the slot inside your computer. The PCI serial port card can only be installed in desktop computers. The PCMCIA serial port card can be installed in laptops but also in desktops with a PCMCIA slot.
Drivers for serial port cards.Since a PCI serial port card is installed directly into the PCI slot in your computer it does not require any drivers to work. This is often a big advantage, not only because it avoids problems with installing and working with the drivers but more often because latency sensitive serial devices will not work proberly with serial ports depedable on drivers. The drivers for a virtual serial port will always create a slight data delay in the communication which latency sensitive devices might not accept.
The PCMCIA serial port card and the ExpressCard serial port card both requires drivers to work. After installing the drivers a virtual COM port will show up in your computers Device Manager. The reason this type of serial port card needs drivers is actually because they are USB based. They create a virtual COM port based on a USB driver architecture. If you are using a quality serial port card this usually works fine, however many low-cost serial port cards often has driver problems making communication hard or even impossible.