m menu image m home m cart

Your header in Here

banner

5 Steps for Selecting the Right USB to Serial adapter

- A Serial Adapter White Paper

If you need to connect a serial device to your computer but your computer doesn't have a serial port, then you need a USB to Serial adapter. Finding the best adapter can be a challenge since there are so many differnt models, types and manufacturers. These 5 steps will help you make the right decision.

The Quick Checklist:

  1. Preferred processor chip: FTDI or Silabs (very reliable)
  2. Preferred serial driver chip: Maxim, Exar, NI or other reputable brand
  3. Minimum 5.0VDC output power at serial connector (ensures reliable data transmission)
  4. Build-in electro-static protection for at least 600W (protects against static electricity)
  5. LED lights for TX and RX activity (nice to have when troubleshooting)

U.S. Converters sells a line of USB to serial adapters that offers all of the above features. We recommend one of the following adapters for all newer operating systems:

 

GOOD

BETTER

BEST
Windows 10 USB to serial adapter
 usb to serial adapter-xs880 thunderlinx usb to serial adapter
USB Serial Adapter PRO USB Serial Adapter Ultimate USB Serial Adapter Thunderlinx™


The details:

  1. Preferred processor chip: FTDI or Silabs.
    This is the utmost most important step. The reason why we highly recommend a USB to serial adapter with a processor chip from either FTDI or Silabs is because these are simply the best. We have extensive experience with these which shows us that these processor chips works with the majority of devices and equipment on the market. The drivers are very stable, easy to install and compatible with all versions of Windows 32/64-bit, Mac, Linux.

  2. Preferred serial driver chip: Maxim, Exar or NI.
    The serial driver chip is what is actually communicating and providing the power signals for your device connected to the USB to serial adapter. We recommend a brand name driver chip from Exar, Maxim or NI because these are very reliable and works well with the FTDI and Silabs processor chips.

  3. At least 5VDC output power at serial connector.
    We recommend a USB to serial adapter with at least 5VDC power output for the TX/RX signals. This will ensure a strong communication signal and that your device gets sufficient power. The output power is measured from signal ground to the Tx signal and the Rx signal.

  4. Build-in static protection to at least 600W.
    Built-in static protection protects the USB to serial adapter against high voltage spikes created either by static electricity or by surges in the supply voltage. This problem can exist both at the USB end and the serial RS232 end.

  5. LED lights for TX and RX activity.
    Not required but very nice to have. Being able to actually see when data is transmitted through the adapter is a big advantage when troubleshooting. This way its easier to find out where the problem lies; if its your computer, your device connected to the adapter or the adapter itself.

Other things to consider would be compatibility with Windows 11. The manufacturer (FTDI) of the processor chips for our USB to Serial adapter "Ultimate", "PRO" and "Thunderlinx" versions have validated that the drivers are fully compatible with the Consumer Preview, Developer Preview versions and officially released consumer versions of Windows 11.

This is great news since you now won't have to spend money on a new USB to serial adapter once you decide to upgrade to Windows 10.

Things to avoid:

  • Avoid adapters with a low-cost processor chip such as Prolific or WCH (WinChipHead). The drivers are poorly written, incompatible with newer operating systems and creates unreliable communication.
  • Avoid adapters with a low output power (less than 5VDC). Low output power makes the communication unreliable or even impossible.

The Architecture of a USB to serial adapter

The design and selection of components of a USB to serial adapter is what determines failure or successful data transfer. Most USB to serial converters has built-in ADDC (Automatic Data Direction Control) so they automatically can control the data flow direction, which makes handshaking obsolete, however this only applies to the RS485 protocol, not RS232.

Below is a simplified schematic of a typical well designed circuitry.

USB to serial adapter circuit

At a block level a USB to serial adapter consists of a USB serial processor chip, a serial driver chip and if the adapter is isolated there will be optocouplers in front of the USB and / or serial ports. The above design consists of a FT2232 USB serial processor from FTDI, which is a dual serial port processor. This processor is combined with a SP213 high-speed RS232 transciever from Exar which makes the overall performance of the adapter solid and reliable.

Step 1: Understanding Your Serial Port Needs

Before diving into the purchase of a serial adapter, it’s essential to understand your specific serial port needs. Start by identifying the types of serial devices you need to connect, such as bar code scanners, printers, or GPS devices. Each device may have different requirements, so knowing what you need upfront is crucial.

Next, consider the number of serial ports required. Some setups might need just one USB cable to connect a single device, while others might require multiple virtual com ports to handle several devices simultaneously. Additionally, determine the type of serial protocol your devices use. Common protocols include RS232, RS485, and RS422, each with its own set of characteristics and compatibility considerations.

Don’t forget to think about the distance between your devices and the computer. Longer distances might necessitate specific types of serial adapters to ensure reliable communication. By thoroughly understanding your serial port needs, you’ll be better equipped to choose the right adapter for your setup.

Step 2: Researching Available Options

Once you have a clear understanding of your serial port needs, it’s time to research the available serial adapter options. Look for adapters that support the serial protocol required by your devices, whether it’s RS232, RS485, or RS422. Ensure the adapter has the necessary number of ports to accommodate all your connected serial devices.

Compatibility with your computer’s operating system and USB port is another critical factor. Check if the adapter works seamlessly with your OS, be it Windows, Mac, or Linux. Performance aspects such as baud rate and data transfer speed are also important. Higher baud rates and faster data transfer speeds can significantly enhance the performance of your connected devices.

Reading reviews and product descriptions can provide valuable insights into the reliability and functionality of different adapters. By thoroughly researching your options, you can find a serial adapter that meets all your requirements.

Step 3: Evaluating Compatibility and Performance

When evaluating serial adapters, compatibility and performance should be at the forefront of your considerations. Ensure the adapter is compatible with both your devices and your computer. Some adapters are plug-and-play, while others may require driver installation. Knowing this in advance can save you time and hassle during setup.

Check if the adapter supports the required baud rate and data transfer speed for your devices. High-quality components and a durable design are indicators of a reliable adapter. Additionally, consider the adapter’s power consumption. Some adapters may require an external power source, especially if they need to support multiple devices or high data transfer rates.

Evaluate the adapter’s overall performance in terms of data transfer speed, reliability, and compatibility with your devices. A well-performing adapter will ensure smooth and efficient communication between your computer and serial devices.

Step 4: Making an Informed Purchase Decision

After conducting thorough research and evaluating your options, it’s time to make an informed purchase decision. Consider the price, features, and performance of each adapter. While it might be tempting to go for the cheapest option, investing in a high-quality adapter can save you from future headaches.

Check if the adapter comes with a warranty or support. This can be a lifesaver if you encounter any issues down the line. Reading reviews from other customers can also provide valuable insights into the adapter’s performance and reliability.

Purchasing from a reputable manufacturer ensures you get a reliable product backed by good customer support. Make sure the adapter is compatible with your devices and computer before finalizing your purchase.

Step 5: Installing and Using Your Serial Adapter

Once you’ve purchased your serial adapter, follow the manufacturer’s instructions for installation. Typically, this involves installing drivers and connecting the adapter to your computer’s USB port. Ensure the drivers are correctly installed to avoid any communication issues.

Connect your serial devices to the adapter and configure the adapter’s settings as needed. This might involve setting the correct baud rate and data transfer parameters. Once everything is set up, you can start using the adapter to connect your serial devices to your computer, ensuring reliable data transfer.

If you encounter any issues, refer to the manufacturer’s documentation or contact their support team for assistance. Proper installation and configuration will ensure your serial adapter works seamlessly with your devices.

 

Further reading:
Further reading: Why most USB to Serial adapters does not work with Windows
Windows 8: USB to serial adapter ready for Windows 8
Overview of all USB to Serial RS232 adapters.
Small form factor adapter: Mini USB to serial adapter

For further information regarding serial data communication, questions or suggestions please contact us.

Download this article as a PDF.




_________

Publishing rights: You may republish this article at your website, newsletter or ebook on the condition that you agree to leave the article, author's signature and all links completely intact.