If you want a new laptop or a new PC with a built-in serial port, then you are probably in trouble. Even more when it comes down to portable computers. The vast majority of offices and homes have replaced the old serial protocols with USBs (i.e. Universal Serial Bus). As a direct consequence, many PC manufacturers no longer provide them as standard hardware.
However, the industrial world still requires the use of serial ports in order for some types of equipment to communicate between them: the RS-422/485 and the RS-232 interfaces. This particular situation creates an important gap between industrial electronics and the work and personal computers.
A brief history of USBs
In 1995, when first introduced, the USB technology was specifically designed to connect PCs with their peripherals and additional components. Before the implementation of USBs, if you wanted to add peripherals to a network or a PC, you first had to power it off, have the expansion card installed, reboot the system, and then have the necessary drivers installed. With USBs, the process was considerably simplified. Human Interface Devices and peripherals could now be added or removed without having to reboot. Though drivers were still necessary, no specialised internals cards were needed any longer.
USB proved to be an amazing expansion for all PCs. Combined with proper PC resources, USB hubs, and proper wiring, one USB port is able to sustain up to 127 devices!
Since its creation, the USB technology has undergone several modifications. Its naming conventions can sometimes become confusing. USB 1.1 refers to Full Speed and Low Speed. USB 2.0 added the High Speed which is faster than Full Speed. To top it all, USB 3.0 added the SuperSpeed in this mix.
It is also useful to know that each new USB version is perfectly compatible with all the previous ones. However, it won’t go faster than them. So, if you plug a USB 3.0 device in a USB 1.1 port, your device will work with the speed of the USB 1.1. The reverse is valid as well. If a USB 1.1 device is plugged in a USB 3.0 port, it will work with the speed of the USB 1.1.
Serial to USB
The equipment that requires the serial connection can now be connected to PCs even if there are no appropriate ports. USB-to-Serial converters can now act like serial port expansion cards. There is one single difference: instead of using the PCI Express slot or the PCI slot, they use a USB interface. When a USB-to-Serial converter gets plugged in a USB port, the driver opens a serial COM port which is used by software apps. This ensures that equipment and other peripherals remain fully functional.
Bridging the gap we have mentioned earlier is now extremely easy: all you have to do is choose the appropriate convertor for your equipment, plug it in your PC’s USB port and connect its other end at your peripheral. As simple as that.