USB to TTL Serial UART RS232 Adaptor (PL2303) (018-USB-PL2303TA)

This is a placeholder topic for “USB to TTL Serial UART RS232 Adaptor (PL2303TA)” comments.

USB to TTL converters are essential for prototyping - they provide a direct interface with the target device. This module connects to your computer USB port and there are 4 wires which connect with your target device.

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My VCC termination is soldered to 5V, yet the RX & TX are 3.3V logic levels not 5V. How can I change these levels ?

Hi Aiden,

You have changed the wire internally from the 3.3v to the 5v pin?

“Open the plastic case (twist the USB connector and then evenly pull apart the plastic case) and change the red wire termination from the pad marked 5V or 3V3.”

Edit - see Graham’s post below.

Hi Stephen,

Thanks for getting back to me.

Yes, the VCC/red wire is soldered to the 5V pad already.

The TX and RX lines are still 3.3V logic though?

With the 5V pad TX/RX should be running at 5V also.

Edit - see Graham’s post below.

That’s what I assumed. I’ve measured it with my oscilloscope and I’m seeing a 3.3 V high value for the TX and RX, but 5V for VCC. I don’t have the hardware and equipment with me today, I’ll measure it again on Monday to confirm.

The TX will still be 0-3.3V, however, that’s well within the TTL range for a logic high on 5V systems. Anything above 0.7V will trigger a logic high on an Arduino (5V system), Raspberry Pi (3.3V system) and so on.

This device is safe to use either 3.3V or 5V signals on the RX pin.

Switching the internal red wire from 3.3V to 5V will simply change the red wire voltage (which “can” be used to power the target circuit, though not essential for most use cases).

Side note: whether-or-not you use the red power wire, you should always connect the ground wire to ensure everything is on the same electrical potential.

Has anybody verified that this works with the Windows 10 driver? The Prolific web site indicates that older versions of the PL2303 are not supported in Windows 10.



Does it work with Windows 10? This is a big problem so far not addressed… for whatever reason Prolific stopped driver support for earlier PL2303s and have deliberately removed them from recent drivers. It is infuriating and causing many problems for people with a mix of devices using old and new PL2303s as the drivers are incompatible.

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Hey Julian and Joneda,

Yes, at the moment it appears that there’s limited/no support for the PL2303 chipsets for Windows 10. The only option that I can think of that may be a workaround to allow for usage of these devices from a machine running Windows 10 would be to run a virtual machine of Windows 7 or another OS capable of using the appropriate drivers. Below I’ve attached a link to a free software that can run on windows 10 to run a VM.

From there any OS with the appropriate drivers should be suitable.

Core Electronics | Support

Thanks. My electronics computer is basic and I’m not sure it will handle a virtual machine on top of all else it is currently running when in the Arduino IDE. AFAIK there are recent PL2303 chips that work fine with current drivers on Win 10 - so the question is, does this device have a recent or old chipset?

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Hey Julian,

This device appears to have an ‘old’ (relatively speaking) chip. This site appears to have relevant information in helping to solve your problem. Make sure to let us know how you go!

Core Electronics | Support

Thank you Bryce! I’ve had issues with this for months and looked everywhere for answers, but never come across this. It answers the question perfectly, explains what the problem is, and the provided solution works like a charm. It is absolutely necessary to do what this post says if you have Windows 10 and are trying to run ‘old’ Prolific 2303 serial chips, (which most gear more than a couple of years old will have). Or counterfeit chips.

I assume this problem will be encountered by anyone purchasing your device, so you could usefully provide that link with each sale.

Even Maynuo, the makers of my relatively expensive electronic load, had no idea what is going on and were no use at all. They provide an expensive USB-serial cable with their loads and this obviously uses an old or counterfeit chip.

Thanks again, saved my sanity.

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Hey Julian,

Glad I could help. Have a great day!

Core Electronics | Support

Unfortunately when Windows updated itself last week, the bad driver got reinstalled, so the “fix” is not successful at preventing unwanted driver updates. I tried the fix again but it didn’t work. The new Prolific driver is very persistent and keeps installing itself out of nowhere even when disconnected from the internet and after deleting everything on the computer that mentions PL2303.

In the end I’ve managed to get the old driver to reinstall but not really sure how, and it seems it might be overridden at any stage. So the problem remains for me. It’s very frustrating and makes using any device connected with the old version of the PL2303 very difficult to use.

To prevent Windows reinstalling the faulty driver requires some registry edits, to change the dates, version, and maybe some other stuff for the “working” driver.

That way when Windows checks the driver, the “latest” driver is already installed and won’t be overwritten.

I don’t have a link, but a web search should find details.

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Hey Robin and Julian,

Here are some links.

Core Electronics | Support

Thanks Robin I’ll give that a go - have found a link that covers the issue, but won’t have time for a few days.

Re Bryce’s links - I don’t want to stop all updates, just this one. Why does Microsoft make everything so hard? :upside_down_face:

Hi Julian,

I wish I knew :smile:. There’s likely some modifications that could be made to the system so that it only partially restricts automatic updating, but it appears that they’ve intentionally made that difficult so it cannot be performed by accident which would cause many more problems for them. Otherwise using another OS and emulating a version of windows with the suitable driver would likely be your best bet. In any case, glad to hear that progress is being made :slight_smile:. All the best with it!

Core Electronics | Support

I don’t understand how this can be both RS232 and TTL at the same time? Doesn’t RS232 use higher voltages and bipolar signals, beyond +/- 5 volts?

Can this interpret RS232 signals? If so, is there some kind of switch or jumper to toggle between TTL and RS232?