FAQ-Prolific (PL2303) Drivers Problems and Solutions

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The Problem & Symptoms

This FAQ concerns problems experienced with USB GPS and USB to Serial Converters that use the PROLIFIC Driver.

The Symptoms are SOB apparently freezing, or slowing down so much that it appears to have frozen Windows.

Unplugging the USB device generally unfreezes SOB & Windows, then replugging the USB device freezes again.

There are a few reasons why this driver problem occurs, mostly:

There are a combination of reasons why this problem exists: they have to do with newer versions of Windows (W7 & W8 & W10) and different versions of the Prolific Driver and different "word sizes" with your computer hardware (32 bit and 64 bit computers).

For instance:

Detailed example with Win8 and 64-bit hardware

Note the following screen shot with 4 Prolific devices connected:

A recent Prolific Driver (v3.4.36.247 aka v1.7.0 dated 26/07/2012)  is installed on a Win8 64-bit laptop:
COM 4 is a new USB to Serial Converter
COM 5 is an older USB to Serial Converter
COM 6 is older model BU353 GPS Mouse from GlobalSat
COM 7 is the new G-STAR IV GPS from GlobalSat

This example shows that the 2 newer devices are compatible with the latest Prolific Driver, but the two older ones are not (as shown by the yellow "!" mark).
An inherent problem with Windows is that you can't load two copies of the same driver of different versions.

Now, the next screen shot shows the same computer, with the same 4 connected devices, but the new Prolific Driver has been unloaded (uninstalled) and an older Prolific Driver has been installed:

The Prolific Driver (v3.3.17.203 aka v1.4.17 dated 29/04/2011)  is installed on a Win8 64-bit laptop:
COM 4 is a new USB to Serial Converter
COM 5 is an older USB to Serial Converter
COM 6 is older model BU353 GPS Mouse from GlobalSat
COM 7 is the new G-STAR IV GPS from GlobalSat

In this example, ALL devices are working with the older Prolific Driver - even though GlobalSat claims the G-STAR IV GPS only works with the new driver!


In this test it should be noted that having both an old and new GPS of the same basic type (BU353 and G-Star IV from GlobalSat) connected at the same time did have a few quirks. For SOB to read and process data from both GPSes they had to be unplugged and replugged in a certain order. And regardless of what games we played, SOB PORTS would not read data from both simultaneously when connected, although if one or other was disconnected then SOB PORTS would see the GPS data from the remaining connected one. So generally then, this would not be an advisable configuration to use, although it is good practice to have two GPS connected with one set as Master (via SOB PORTS), but it is unlikely that both would be these USB types. A good scenario is for the Ship's GPS to be nominated as the Master, and a USB type as the backup in case you loose data from the Ship's GPS for any reason.


These test were carried out on a Win 8 64-bit laptop. If using different Windows version, or a 32 bit laptop then your results are likely to vary. The point here is that the Prolific driver must be matched to all of the USB devices; the Windows version and the Hardware (32/64 bit).

In almost all of our tests with various configurations we found the v1.4 driver to be the most compatible, so probably best to start with this driver and check Device Manager and SOB PORTS and SOB before uninstalling and installing a different Prolific Driver version.

Note that at the time of writing (Jun 2015) the latest (known) Prolific Driver is v3.4.48.272 dated 5/02/2013. This is known to work with W8 and the G-Star IV GPS, but not with previous models of hardware.

Driver Versions

Following are various versions of the Prolific Driver with some detail about their chances of working with your system:
Other versions of the driver are available on the Internet, or may have come with your device, it may be necessary to experiment with different versions depending on your combination of devices and hardware. See section below for best ways to uninstall the Prolific driver if necessary.

Older Prolific Driver versions

Win 2000, Win XP download

Win Vista  download

Prolific Driver Ver 1.4.17

Win 7 : 32 bit (64 bit unknown)

W8 and 64 bit with G-STAR IV GPS


Prolific Driver Ver 1.7

Win 8 : 32 or 64 bit hardware



Do not use the GPS View, or GPS Info, application that comes with your Prolific device as this interferes with SOB's ability to communicate with the USB port.

Some Advanced Tips

NOTE: If you do not understand what a Registry is or how to use it we strongly advise you not to delve into this section, it is included here for advanced computer users only.

Here are a couple of extra tips to try if your SOB still freezes, or the USB GPS data is erratic, after installing the correct Prolific driver:

Checking what version of Prolific Driver is installed:

Windows 8

Run Device Manager - easiest way is to press the button on the SOB PORTS screen!

Via Windows - next easiest way is to press AND HOLD the Windows Key (generally lower-left of keyboard, shaped like 4 windows), while the Windows key is down, press the R key to pop-up the "Run" window.

Type devmgmt.msc and OK button.

A window similar to the following will appear:

Open the "Ports (COM & LPT)" branch as shown above, find the Prolific Entry and Double-Click on it.

Select "Properties" from the pop-up menu, and select the "Driver" page as shown next:

The Prolific Driver Version is displayed on this page.

Uninstalling Prolific Drivers

You can use Control Panel's Uninstall routine, or the Prolific Driver Installation itself will give an uninstall option on its opening menu if it finds a previously installed driver.

HOWEVER - neither of these methods fully uninstalls all remnants of the driver. In fact it is exceedingly difficult to completely remove all traces of a previously installed driver.

Here is one method to do a more complete "uninstall" than that performed by Control Panel's, or the devices' Uninstall program:

From Device Manager, turn on "Show Hidden Devices"

Find the Driver in the list (if it doesn't appear you may need to plug in the device), the "greyed out" entries in the following example picture means that they are not connected, but the "show hidden" allows them to display anyway...

Right-Click the entry and select Uninstall from the pop-up menu (or highlight the entry and press the Delete key):

In the Confirm Uninstall window, tick the "Delete Driver Software..." before confirming with the OK button.

The devices Uninstall app may, or may not, appear at this stage and continue the uninstalling.

It is best practice to now remove any connected devices and reboot your computer.

Advanced Driver Uninstallation

The procedure above usually does enough of an uninstallation to not affect any future driver re-installation, but this is not always the case.

On rare occasions, if you continue to experience erratic driver operation or conflicts, it may be necessary to attempt to remove all traces of the old driver.

For very advanced computer users you can sift through the Registry and remove all references, then find the correct INF and SYS files in the Windows folders and delete them and all supporting files - the relevant INF (which has a matching SYS) file and Registry codes can be found by looking up the Details (such as INF file name) in the driver property sheet from Device Manager, as shown here:


All the above information is provided in good faith but is not guaranteed to work for all users.
Additionally, some information provided can potentially cause harm to your computer and may prevent proper operation.
Digiboat accepts no responsibility for any harm caused directly or indirectly to your computer or devices.

(c) Digiboat Pty Limited 2015