![]() However, the characteristics of the virtual COM port are not exactly the same as a real internal COM port, mainly due to data latency which means that if very sensitive and precise data transfer is required, the USB to serial adapter might be unreliable and not a desired solution. This virtual COM port can be accessed and used as if it was a built-in serial COM port. When the USB to serial adapter is connected to the computer via the USB port the driver on the computer creates a virtual COM port which shows up in Device Manager on Windows, and under /dev on Linux and MacOS. for Windows and MacOS, WCH CH340, Silicon Labs 210x, Prolific PL2303 ). Some chip models have drivers installed by default, including FTDI, while drivers for other chip models must be manually installed (e.g. įor the computer to be able to detect and process the data signals drivers must be installed on the computer. The USB processor sends the processed USB signals to a serial driver chip which applies the correct voltages and sends the processed data signals to the serial output. Since many serial devices with a RS232, RS485 or RS422 port are still in use and even still produced today, the disappearance of the serial COM port from personal computers has created a need for the USB to serial adapter.ĭie of a PL2303HX USB to Serial Bridge Controller manufactured by Prolific Technology.Īs a simplified example a typical standard USB to serial adapter consists of a USB processor chip which processes the USB signals. By the mid-2000s, some computers had both a serial COM port and a USB port however, many no longer had a serial COM port by that time, and today most modern computers have no serial COM port but instead only USB ports. By the late '90s, many computer manufacturers started to phase out the serial COM port in favor of the USB port. Historically, most personal computers had a built-in D-sub serial RS232 port, also referred to as a COM port, which could be used for connecting the computer to most types of serial RS232 devices. The non-isolated version has no protection against static electricity or voltage surges, which is why this version is usually recommended for only non-critical applications and at short communication ranges. The isolated version has opto-couplers and/or surge suppressors to prevent static electricity or other high-voltage surges to enter the data lines thereby preventing data loss and damage to the adapter and connected serial device. ![]() ![]() USB serial adapters can be isolated or non-isolated. The primary application scenario is to enable USB-based computers to access and communicate with serial devices featuring D-Sub (usually DB9 or DB25) connectors or screw terminals, where security of the data transmission is not generally an issue. Currently, USB to TTL-level UART converters are used extensively by students and hobbyist as they can be directly interfaced to microcontrollers.Īdapters for converting USB to other standard or proprietary protocols also exist however, these are usually not referred to as a serial adapter. USB to serial RS232 adapters are often used with consumer, commercial and industrial applications and USB to serial RS485/RS422 adapters are usually mainly used only with industrial applications. ![]()
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