17in (43cm) 1-Port USB to Serial Adapter Cable, USB-A to DB9 RS232, USB to RS232 Adapter, Prolific Chipset - M/M

Questions & Answers

Why did the software not install properly in macOS High Sierra (10.13) or later?
Starting in High Sierra 10.13, macOS enforces stricter security policies than previous revisions. As a result of these changes, software packages, like those used in this installation, will need to be allowed within the macOS Security and Privacy settings, immediately after the software has been installed, in order for the device to operate. To allow the software, follow these steps after you've completed installation on your Mac: Open System Preferences . Open Security & Privacy . Click the Allow button near the bottom of the General tab. Note: The option to allow the software will be available within the Security & Privacy settings for 30 minutes. If the software is not allowed within that time frame, the software must be reinstalled in order for macOS to grant the opportunity to allow it again.

I am receiving an error when I try to install the drivers in Windows 8 64 bit. What do I do?
Some driver installation packages may require you to disable driver signature enforcement in Windows 8, which will allow unsigned driver packages to be installed on your system. Note: Before you continue, save any open documents and close all open programs. To disable driver signature enforcement, complete the following: Press the Windows key + C . Click Settings > Change PC Settings . In the left pane, click General . In the right pane, under Advanced startup , click Restart now . When your system finishes restarting, complete the following: Click Troubleshoot > Advanced options > Startup Settings > Restart . Press 7 . When your computer restarts, driver signature enforcement will be disabled and you can install your drivers. Note: When you restart your computer after you install your drivers, driver signature enforcement will be enabled again. This does not prevent your newly installed drivers from working, but does prevent any other unsigned drivers from being installed until driver signature enforcement is disabled.

I am receiving an error when I try to install the drivers in Windows 8.1 64 bit. What do I do?
Some unsigned driver packages require Driver Signature Enforcement to be temporarily disabled before they can be installed. After the driver is installed and the computer is restarted, Driver Signature Enforcement is automatically re-enabled. Explanation: If Windows blocks the driver installation because the driver is unsigned, you can temporarily disable Driver Signature Enforcement and then install the driver. Before you begin, save any open files and close all applications. To disable Driver Signature Enforcement: Open Settings . Navigate to Update & Security > Recovery Under Advanced startup , select Restart now . After the computer restarts, select: Troubleshoot Advanced options Startup Settings Restart When the Startup Settings menu appears, press 7 or F7 to Disable driver signature enforcement . Install the driver. Restart the computer normally. After the computer restarts, Driver Signature Enforcement is automatically enabled again. This does not affect the operation of the newly installed driver, but Windows will once again prevent additional unsigned drivers from being installed until Driver Signature Enforcement is temporarily disabled.

I am receiving an error when I try to install the drivers in Windows 10 / 11 64 bit. What do I do?
Some unsigned driver packages require Driver Signature Enforcement to be temporarily disabled before they can be installed on 64-bit versions of Windows 10 or Windows 11. After the driver is installed and the computer is restarted, Driver Signature Enforcement is automatically re-enabled. Explanation: If Windows blocks the driver installation because the driver is unsigned, you can temporarily disable Driver Signature Enforcement and then install the driver. Before you begin, save any open files and close all applications. To disable Driver Signature Enforcement: Open the Start menu. Select Power . Press and hold the Shift key, then select Restart . After the computer restarts, select: Troubleshoot Advanced options Startup Settings Restart When the Startup Settings menu appears, press 7 or F7 to Disable driver signature enforcement . Install the driver. Restart the computer normally. After the computer restarts, Driver Signature Enforcement is automatically enabled again. This does not affect the operation of the newly installed driver, but Windows will once again prevent additional unsigned drivers from being installed until Driver Signature Enforcement is temporarily disabled.

How do I install my serial card in Windows Vista / 7 / 8? (.exe method)
Prior to installing this device, ensure that your operating system is up to date (for example, you have installed the most recent service pack). To install the driver: Download the latest drivers from the StarTech.com website ( http://www.startech.com/Support ). You can find the part number and product ID on the product’s packaging. Note: Windows will typically save the files to the Downloads folder that is associated with your user account (for example, C:Users your_name Downloads). Once the download is complete, right-click the zip folder that you downloaded, select Extract All , and follow the on-screen instructions. In the list of extracted files, right-click the Setup.exe file and select Run as Administrator . Note: If the Run as Administrator option is not available, you might be attempting to run the installer from within the zipped file. Extract the files using the instructions in Step 2. Follow the on-screen prompts to install the device drivers and restart the computer when prompted. Once Windows has restarted, connect the USB serial adapter to your computer. Your computer will automatically complete the driver installation and your device should be ready to use.

How do I install my USB serial adapter in Windows XP? (.exe method)
Prior to installing this device, ensure that your operating system is up to date (for example, you have installed the most recent service pack). To install the driver: Download the latest drivers from the StarTech.com website ( http://www.startech.com/Support ). You can find the part number and product ID on the product’s packaging. Note: Windows will typically save the files to the Downloads folder that is associated with your user account (for example, C:Documents and Settings your_name My DocumentsDownloads). Once the download is complete, right-click the zip folder that you downloaded, select Extract All , and follow the on-screen instructions. In the list of extracted files, double-click the Setup.exe file. Follow the on-screen prompts to install the device drivers and restart the computer when prompted. Once Windows has restarted, connect the USB serial adapter to your computer. Your computer will automatically complete the driver installation and your device should be ready to use.

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.

Everything is hooked up but nothing is working. What should I do?
When you troubleshoot issues with a serial device, there are some quick tests that you can complete to rule out potential problems. You can test to make sure that the following components are working correctly and are not the source of the issue: Serial cables Serial ports Serial devices To test your setup components, try the following: Use the serial cable, serial port, and serial device in another setup to see if the problem is with the components or the setup. Use a different serial cable, serial port, and serial device in your setup to see if the problem persists. Ideally, you should test a component that you know works in another setup. When you test your cables, it is recommended that you do the following: Test each cable individually. Use short cables when you are testing. When you test the serial ports and serial device, it is recommended that you do the following: Press the Windows key + R , type devmgmt.msc , and press Enter to open Device Manager . Check to see if your device is listed under Ports (COM & LPT) . Make sure that the COM port number is the correct number for the serial device and that the software being used to connect the computer to the serial device uses the correct COM port number. If the device is listed with an error, follow the instructions on the website to reinstall the drivers. Note: Some serial devices work only if the COM port number is between a certain range. For example, COM1 to COM4. Perform a serial loopback test. See this FAQ on how to perform a RS-232 serial loopback test: http://www.startech.com/faq/serial_loopback_test_rs232_windows

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.

How do I confirm that Windows detects my USB device?
To confirm that Windows detects your USB device, complete the following: Press the Windows key+ R , type devmgmt.msc , and press Enter . In Device Manager , under the appropriate heading, confirm that your expansion card is listed and that there isn't an exclamation mark next to it. For example, a USB controller card would be under Universal Serial Bus controllers . Your USB device is listed according to the name of the chipset. To determine the name of the chipset of your USB device, navigate to www.StarTech.com and look on the Technical Specifications tab for your product.

How can I check if my USB device is properly detected by Mac OS?
To confirm that the Mac OS detects your USB device, complete the following: Click the Apple icon. Click About This Mac . Click More Info or System Report . Under the appropriate heading, confirm that your USB device is listed and that there isn't an error. For example, a network card would be under Ethernet Cards . You may need to refresh the System Information page after you plug in your device. To do so, press Command + R with the System Information page open. Your USB device is listed according to the name of the chipset. To determine the name of the chipset of your USB device, navigate to www.StarTech.com and look on the Technical Specifications tab for your product.

The COM numbers in Device Manager change after I reboot or re-connect the product. How do I fix this?
Use a USB to Serial product that features COM Port Retention. These products will store settings that are unique to the connected device in non-volatile memory, allowing you to retain the desired settings regardless of the USB Port to which the adapter is connected.

How do I check to ensure the COM port is listed properly in Windows?
To ensure your serial device is installed properly, complete the following: Open the Device Manager by pressing the Windows Key + R . Type “devmgmt.msc” and press Enter . Expand the Ports (COM & LPT) section. You should see a COM number in brackets to the right of each port, and there should not be any exclamation points or question marks next to the entries in the list.

How to Change COM Port Number on Windows
Some serial devices require a specific COM port number to function. In these cases, consult the manual of your serial device to determine the correct number to use. To change the COM port number of a serial device in Device Manager, complete the following: Open the Device Manager by pressing the Windows Key + R . Type “devmgmt.msc” and press Enter . Expand the Ports (COM & LPT) section. Right-click the COM port and select Properties . Click the Port Settings tab and click Advanced . Change the COM port number to an available COM port number. Note : Multiple serial ports cannot share the same COM port number. Restart your computer. Note : Even if you change the COM port number back to the original number, you still need to restart your computer.