Android Question USB - Serial RS232

[Hamo]

I have two tablets of different make, model but both with V4.x.x
The USB ports functioned as host and worked perfectly with USB flash drives but failed to detect a USB Serial cable when plugged in. The USB-Serial lead has the Prolific 2303HX chipset. To cut a long story short, the problem was fixed after I ran the app USB Host Diagnostics.
First it told me to disconnect any USB devices, then it started scanning and asked me to connect the USB device. It didn't stop scanning but told me that if so, I should press the Back button anyhow to see if any results. When I did this, it then gave me this message. "A possible problem with your firmware has been detected which may cause apps to be unable to use USB host. Try to fix ? NO / YES
I selected YES, and a second later it told me it tried to fix and asked me to re-boot. After the re-boot, it worked perfectly. What did the app Usb Host Diagnostics do to fix the problem ? Is this something I can add to my code ?
Hamo

 

[Erel]

Is your device rooted?

 

[Hamo]

No, my 2 devices are not rooted.
Hamo

 

[Erel]

Not sure what it did. On many devices you need to apply this fix: http://www.b4x.com/android/forum/threads/pl2303-usb-to-rs232-adaptor-driver.11449/page-3#post-121049

However it is only possible to do it on rooted devices.

 

[Hamo]

Not sure what it did. On many devices you need to apply this fix: http://www.b4x.com/android/forum/threads/pl2303-usb-to-rs232-adaptor-driver.11449/page-3#post-121049

However it is only possible to do it on rooted devices.

Thanks Erel. You asked if my devices were rooted and I replied NO, because I did not root them.
They were as I bought them new. How can I tell if they are rooted ?
Hamo

 

[Erel]

You can use an app such as this one: https://play.google.com/store/apps/details?id=com.joeykrim.rootcheck&hl=en

 

[drahneir]

I always had prolems with Prolific devices when changing the OS. After the change to Windows 8 there was no driver available. So I took devices with FTDI chipset. They are a bit more expensive, but are worth the money. No more problems till then.

 

[Hamo]

This was not an issue with the Prolific chipset. I tried 3 different usb serial leads from different makers and my two tablets failed to detect the usb device. After running the app Usb Host Diagnostics and letting it fix the problem they were all detected as usb devices. So what was the problem that the app Usb Host Diagnostics fixed ?
Hamo

 

[Hamo]

This was not an issue with the Prolific chipset. I tried 3 different usb serial leads from different makers and my two tablets failed to detect the usb device. After running the app Usb Host Diagnostics and letting it fix the problem they were all detected as usb devices. So what was the problem that the app Usb Host Diagnostics fixed ?
Hamo

Erel, you were right, these two tablets were both rooted, that's the way they came from the manufacturer.
Hamo