3ft (1m) USB to Serial Cable, DB9 Male RS232 to USB Converter, Prolific IC, USB to Serial Adapter for PLC/Printer/Scanner/Switch, USB to COM Port Adapter, Windows/Mac

Questions & Answers

Serial communication is not working. Is the problem caused by the adapter or my serial software application?
Older applications that use serial communication often use legacy hardware addresses that do not work with PCI, PCIe, or USB to Serial products. We recommend contacting the software provider/support team to check if this is the case.

How can I make sure my serial port is working in Windows?
To check whether or not an RS-232 serial port is working, perform an RS-232 loopback test by doing the following: If your serial port is not female, convert it by taking a female/female cable or gender changer and plugging it into the serial port. Take a metal paperclip or wire and cross pins 2 and 3. If you look closely at the female end, the pins should be numbered. Open a telnet session on the COM port number of the device that you are testing. To find out the COM port number, refer to the following FAQ: https://www.startech.com/faq/com-port-listing-windows . Note: To open a telnet session on the COM port, you need a telnet client like PuTTY or Hyper Terminal. Windows XP comes with Hyper Terminal. When the session is open, anything you type into it you should see. The loopback test fails when you cannot see what you are typing. If the loopback test fails, make sure that the serial cable or gender changer that you are using works and that the adapter is in the correct port. You can check multiple ports at the same time by opening multiple sessions, putting the loopback adapter on one port, and trying to type into each session. When you can see what you are typing, you know that the COM port is working and you can see which port number the physical serial port is. Close the window for the port that you just tested to speed up the testing of the remaining serial ports. For products related to this article, click here .

Why does my USB device stop working after my computer wakes back up from sleep mode in Windows?
If the USB device does not work after your computer has been in extended hibernation, it is likely that Windows has automatically turned off the USB Root hub to save power. The steps below outline how to configure the USB root hub to stay on during hibernation, to prevent this from happening. Windows 10 / 8 On your keyboard, press the Windows key + X and select Control Panel . Click Hardware and Sound , then click Power Options . Click Change plan settings for the plan you want to change. Click Change advanced power settings . Click the plus sign (+) next to “USB settings” and “USB selective suspend setting” to expand the options and change the setting to Disabled . Click OK to apply the setting. Note : You may need to disconnect and re-connect your USB device after applying these settings to re-establish the connection. Windows 7 / Vista Click the Start button and select Control Panel . Click Hardware and Sound , then click Power Options . Click Change plan settings for the plan you want to change. Click Change advanced power settings . Click the plus sign (+) next to “USB settings” and “USB selective suspend setting” to expand the options and change the setting to Disabled . Click OK to apply the setting. Note : You may need to disconnect and re-connect your USB device after applying these settings to re-establish the connection. Windows XP On your desktop, right-click the My Computer icon and select Properties . Click the Device Manager tab. Expand Universal Serial Bus controllers by clicking the arrow to the left of it. Right-click the first USB Root Hub device and select Properties . Click the Power Management tab. Clear the box next to Allow the computer to turn off this device to save power . Click OK to apply the setting. Repeat steps 4-7 for any remaining devices in the Universal Serial Bus Controllers section with “ Root Hub ” in the name. Note : You may need to disconnect and re-connect your USB device after applying these settings to re-establish the connection.