USB to Serial converter code pl2303

USB to Serial converter code pl2303

[Magnus]

Hi,

I just bought a Plexgear USB to serial adapter that i wanted to use
for a robot that im building.

This works fine via a serial connection, but now i want my new
Raspberry PI mini computer to handle the chip and it only has USB
unless i connect some special Raspberry converter that i cant buy
where i live atm and dont know if itll work for this kind of
controller chip.

After plugging in the plexgear adapter into my linux boxes:
Fedora 18, Debian 3.11.0-15-generic #25-Ubuntu and weezy it doesnt
send any commands to the servo controller chip on the other side
of the converter.

I can open the port /dev/ttyUSB0 and send to it with stty, but not
a beep on the other side. I have also set the tty Baudrate manually to
2400 but this made no difference. My code does this as well including
setting stopbit
parity and so on.

The robot controller chip only handles 2400 Baud but is fast enough
for the connected servos to spin around as fast as possible.
Those are up to 5 regular rc-servos running on 9 volts and
controlled via a FT639/EDE639 chip that i made some code for
many years ago for Linux.


Some data i get from Linux and Plexgear converter follows:

$ lsmod | grep pl2303
pl2303                 18527  0 
usbserial              38603  1 pl2303


$ lsusb
Bus 005 Device 007: ID 067b:2303 Prolific Technology, Inc.
PL2303 Serial Port

$ lsusb -v

Bus 005 Device 007: ID 067b:2303 Prolific Technology, Inc.
PL2303 Serial Port

Couldn't open device, some information will be missing
(My comment... hmm, but it can read from it ?)..

Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x067b Prolific Technology, Inc.
  idProduct          0x2303 PL2303 Serial Port
  bcdDevice            3.00
  iManufacturer           1 
  iProduct                2 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           39
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           3
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0 
      bInterfaceProtocol      0 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x000a  1x 10 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0

I can code some, but i dont know where to start so any
help on this is highly appreciated.


When i google to find info on adapters i read that
"bMaxPacketSize0 64" indicates that its a counterfeit product
but i paid 250 Swedish for it and that not very cheap for a
univeristy student i think.

This is what it looks like,
(It has a sticker on it saying its from China):
https://serialio.com/sites/default/files/images/USB-RS232-Cable-med-wm1.jpg


Sincerely,
Magnus-swe

Re: USB to Serial converter code pl2303

[Johan Hovold]

[ Please make sure to CC the linux-usb list as well. ]

On Tue, Feb 18, 2014 at 02:57:45AM +0100, Magnus wrote:
> After plugging in the plexgear adapter into my linux boxes:
> Fedora 18, Debian 3.11.0-15-generic #25-Ubuntu and weezy it doesnt
> send any commands to the servo controller chip on the other side
> of the converter.
> 
> I can open the port /dev/ttyUSB0 and send to it with stty, but not
> a beep on the other side. I have also set the tty Baudrate manually to
> 2400 but this made no difference. My code does this as well including
> setting stopbit parity and so on.

First verify that the converter works by connecting it to a serial port
on your PC and using a terminal program such as minicom at 115200 baud
(and the same port settings including flow control) on both ends.

Also make sure you got the wiring right (e.g. use a null-modem cable).

> Some data i get from Linux and Plexgear converter follows:
> 
> $ lsmod | grep pl2303
> pl2303                 18527  0 
> usbserial              38603  1 pl2303
> 
> 
> $ lsusb
> Bus 005 Device 007: ID 067b:2303 Prolific Technology, Inc.
> PL2303 Serial Port
> 
> $ lsusb -v
> 
> Bus 005 Device 007: ID 067b:2303 Prolific Technology, Inc.
> PL2303 Serial Port
> 
> Couldn't open device, some information will be missing
> (My comment... hmm, but it can read from it ?)..
> 
> Device Descriptor:
>   bLength                18
>   bDescriptorType         1
>   bcdUSB               1.10
>   bDeviceClass            0 (Defined at Interface level)
>   bDeviceSubClass         0 
>   bDeviceProtocol         0 
>   bMaxPacketSize0        64
>   idVendor           0x067b Prolific Technology, Inc.
>   idProduct          0x2303 PL2303 Serial Port
>   bcdDevice            3.00
>   iManufacturer           1 
>   iProduct                2 
>   iSerial                 0 
>   bNumConfigurations      1
>   Configuration Descriptor:
>     bLength                 9
>     bDescriptorType         2
>     wTotalLength           39
>     bNumInterfaces          1
>     bConfigurationValue     1
>     iConfiguration          0 
>     bmAttributes         0x80
>       (Bus Powered)
>     MaxPower              100mA
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        0
>       bAlternateSetting       0
>       bNumEndpoints           3
>       bInterfaceClass       255 Vendor Specific Class
>       bInterfaceSubClass      0 
>       bInterfaceProtocol      0 
>       iInterface              0 
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x81  EP 1 IN
>         bmAttributes            3
>           Transfer Type            Interrupt
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x000a  1x 10 bytes
>         bInterval               1
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x02  EP 2 OUT
>         bmAttributes            2
>           Transfer Type            Bulk
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval               0
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x83  EP 3 IN
>         bmAttributes            2
>           Transfer Type            Bulk
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval               0
> 
> I can code some, but i dont know where to start so any
> help on this is highly appreciated.
> 
> When i google to find info on adapters i read that
> "bMaxPacketSize0 64" indicates that its a counterfeit product
> but i paid 250 Swedish for it and that not very cheap for a
> univeristy student i think.

This device is likely not a clone, but should be supported by the pl2303
driver either way (at least at 115200 baud).

Good luck,
Johan

Re: USB to Serial converter code pl2303

[Magnus]

>[ Please make sure to CC the linux-usb list as well. ]
Sure Johan.

I have visited several stores today that should have had either
a null-modem or another type of USB to serial converter but
unfortunately this was not the case.
The store owners even thought that this should be something
that they had available at all times and dove down into piles
of cables but came up empty. 

The brand of this USB-Serial converter is sold by or as
"Plexgear" or "Marquant".

Absolutely no info on the adapter is provided in the package
other then a mini-cd saying its a "prolific" product.

I tried to send initialization code "117" followed by
servo movement codes to it via gtkterm.
The only time the adapter responded was at 115200 Baud.

I need an adapter that can handle 2400 Baud to talk to the
ft639/ede639 servo controller chip or possibly a pl2303 driver
that is improved. I have looked at vscom, a very similar
looking adapter on all counts except shape.
This adapter uses a linux driver called "ftdi_sio"
from info i have read on the net.

What im really looking for here is an usb to serial
adapter that works for 2400 Baud and not only 115200.
I guess ill have to buy a new one from somewhere, but im
missing the what and the where :)

Sincerely,
Magnus




> [ Please make sure to CC the linux-usb list as well. ]
> 
> On Tue, Feb 18, 2014 at 02:57:45AM +0100, Magnus wrote:
> > After plugging in the plexgear adapter into my linux boxes:
> > Fedora 18, Debian 3.11.0-15-generic #25-Ubuntu and weezy it doesnt
> > send any commands to the servo controller chip on the other side
> > of the converter.
> > 
> > I can open the port /dev/ttyUSB0 and send to it with stty, but not
> > a beep on the other side. I have also set the tty Baudrate manually to
> > 2400 but this made no difference. My code does this as well including
> > setting stopbit parity and so on.
> 
> First verify that the converter works by connecting it to a serial port
> on your PC and using a terminal program such as minicom at 115200 baud
> (and the same port settings including flow control) on both ends.
> 
> Also make sure you got the wiring right (e.g. use a null-modem cable).
> 
> > Some data i get from Linux and Plexgear converter follows:
> > 
> > $ lsmod | grep pl2303
> > pl2303                 18527  0 
> > usbserial              38603  1 pl2303
> > 
> > 
> > $ lsusb
> > Bus 005 Device 007: ID 067b:2303 Prolific Technology, Inc.
> > PL2303 Serial Port
> > 
> > $ lsusb -v
> > 
> > Bus 005 Device 007: ID 067b:2303 Prolific Technology, Inc.
> > PL2303 Serial Port
> > 
> > Couldn't open device, some information will be missing
> > (My comment... hmm, but it can read from it ?)..
> > 
> > Device Descriptor:
> >   bLength                18
> >   bDescriptorType         1
> >   bcdUSB               1.10
> >   bDeviceClass            0 (Defined at Interface level)
> >   bDeviceSubClass         0 
> >   bDeviceProtocol         0 
> >   bMaxPacketSize0        64
> >   idVendor           0x067b Prolific Technology, Inc.
> >   idProduct          0x2303 PL2303 Serial Port
> >   bcdDevice            3.00
> >   iManufacturer           1 
> >   iProduct                2 
> >   iSerial                 0 
> >   bNumConfigurations      1
> >   Configuration Descriptor:
> >     bLength                 9
> >     bDescriptorType         2
> >     wTotalLength           39
> >     bNumInterfaces          1
> >     bConfigurationValue     1
> >     iConfiguration          0 
> >     bmAttributes         0x80
> >       (Bus Powered)
> >     MaxPower              100mA
> >     Interface Descriptor:
> >       bLength                 9
> >       bDescriptorType         4
> >       bInterfaceNumber        0
> >       bAlternateSetting       0
> >       bNumEndpoints           3
> >       bInterfaceClass       255 Vendor Specific Class
> >       bInterfaceSubClass      0 
> >       bInterfaceProtocol      0 
> >       iInterface              0 
> >       Endpoint Descriptor:
> >         bLength                 7
> >         bDescriptorType         5
> >         bEndpointAddress     0x81  EP 1 IN
> >         bmAttributes            3
> >           Transfer Type            Interrupt
> >           Synch Type               None
> >           Usage Type               Data
> >         wMaxPacketSize     0x000a  1x 10 bytes
> >         bInterval               1
> >       Endpoint Descriptor:
> >         bLength                 7
> >         bDescriptorType         5
> >         bEndpointAddress     0x02  EP 2 OUT
> >         bmAttributes            2
> >           Transfer Type            Bulk
> >           Synch Type               None
> >           Usage Type               Data
> >         wMaxPacketSize     0x0040  1x 64 bytes
> >         bInterval               0
> >       Endpoint Descriptor:
> >         bLength                 7
> >         bDescriptorType         5
> >         bEndpointAddress     0x83  EP 3 IN
> >         bmAttributes            2
> >           Transfer Type            Bulk
> >           Synch Type               None
> >           Usage Type               Data
> >         wMaxPacketSize     0x0040  1x 64 bytes
> >         bInterval               0
> > 
> > I can code some, but i dont know where to start so any
> > help on this is highly appreciated.
> > 
> > When i google to find info on adapters i read that
> > "bMaxPacketSize0 64" indicates that its a counterfeit product
> > but i paid 250 Swedish for it and that not very cheap for a
> > univeristy student i think.
> 
> This device is likely not a clone, but should be supported by the pl2303
> driver either way (at least at 115200 baud).
> 
> Good luck,
> Johan

Re: USB to Serial converter code pl2303

[Johan Hovold]

On Wed, Feb 19, 2014 at 05:44:20PM +0100, Magnus wrote:
> >[ Please make sure to CC the linux-usb list as well. ]
> Sure Johan.

[ And please try to avoid top-posting... ]

> The brand of this USB-Serial converter is sold by or as
> "Plexgear" or "Marquant".
> 
> Absolutely no info on the adapter is provided in the package
> other then a mini-cd saying its a "prolific" product.
> 
> I tried to send initialization code "117" followed by
> servo movement codes to it via gtkterm.
> The only time the adapter responded was at 115200 Baud.
> 
> I need an adapter that can handle 2400 Baud to talk to the
> ft639/ede639 servo controller chip or possibly a pl2303 driver
> that is improved.

The pl2303-driver can handle 2400 baud, but not sure exactly what baud
rates are available for a cloned/pirated pl2303 chip (if that is what
you've got). 115200 baud should be supported, though.

> I have looked at vscom, a very similar
> looking adapter on all counts except shape.
> This adapter uses a linux driver called "ftdi_sio"
> from info i have read on the net.

That driver also works at 2400 baud.

> What im really looking for here is an usb to serial
> adapter that works for 2400 Baud and not only 115200.
> I guess ill have to buy a new one from somewhere, but im
> missing the what and the where :)

I only suggested using 115200 baud as a way to verify your setup. Once
you do that you can try 2400.

Good luck,
Johan

Re: USB to Serial converter code pl2303

[Karsten Malcher]

Am 19.02.2014 18:00, schrieb Johan Hovold:
> I need an adapter that can handle 2400 Baud to talk to the
> ft639/ede639 servo controller chip or possibly a pl2303 driver
> that is improved.
> The pl2303-driver can handle 2400 baud, but not sure exactly what baud
> rates are available for a cloned/pirated pl2303 chip (if that is what
> you've got). 115200 baud should be supported, though.

We have tested different baud rates with the PL2303HX china clones.
All are working including non standard baud rates.
But the non standard baud rates are only available with the modified driver from Frank Schäfer.

Cheers
Karsten
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Re: USB to Serial converter code pl2303

[Johan Hovold]

On Wed, Feb 19, 2014 at 06:05:54PM +0100, Karsten Malcher wrote:
> Am 19.02.2014 18:00, schrieb Johan Hovold:
> > I need an adapter that can handle 2400 Baud to talk to the
> > ft639/ede639 servo controller chip or possibly a pl2303 driver
> > that is improved.
> > The pl2303-driver can handle 2400 baud, but not sure exactly what baud
> > rates are available for a cloned/pirated pl2303 chip (if that is what
> > you've got). 115200 baud should be supported, though.
> 
> We have tested different baud rates with the PL2303HX china clones.
> All are working including non standard baud rates.

Ok, good, so 2400 baud should work.

> But the non standard baud rates are only available with the modified
> driver from Frank Schäfer.

What driver is that? The latest clone-related patch from Frank that I've
seen stated:

	"According to Prolific, several (unauthorized) cheap and less
	 functional clones of the PL2303HX chip are in circulation. [1]
	 I've had the chance to test such a cloned device and it turned
	 out that it doesn't support any baud rates above 115200 baud
	 (original: 6 Mbaud) It also doesn't support the divisior based
	 baud rate encoding method, so no continuous baud rate adjustment
	 is possible."

Thanks,
Johan
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Re: USB to Serial converter code pl2303

[Karsten Malcher]

Am 19.02.2014 18:14, schrieb Johan Hovold:
> On Wed, Feb 19, 2014 at 06:05:54PM +0100, Karsten Malcher wrote:
>> Am 19.02.2014 18:00, schrieb Johan Hovold:
>>> I need an adapter that can handle 2400 Baud to talk to the
>>> ft639/ede639 servo controller chip or possibly a pl2303 driver
>>> that is improved.
>>> The pl2303-driver can handle 2400 baud, but not sure exactly what baud
>>> rates are available for a cloned/pirated pl2303 chip (if that is what
>>> you've got). 115200 baud should be supported, though.
>> We have tested different baud rates with the PL2303HX china clones.
>> All are working including non standard baud rates.
> Ok, good, so 2400 baud should work.

Yes - this should be no problem with every usb converter.
I have different one and all of them are usable now.

>
>> But the non standard baud rates are only available with the modified
>> driver from Frank Schäfer.
> What driver is that? The latest clone-related patch from Frank that I've
> seen stated:
>
> 	"According to Prolific, several (unauthorized) cheap and less
> 	 functional clones of the PL2303HX chip are in circulation. [1]
> 	 I've had the chance to test such a cloned device and it turned
> 	 out that it doesn't support any baud rates above 115200 baud
> 	 (original: 6 Mbaud) It also doesn't support the divisior based
> 	 baud rate encoding method, so no continuous baud rate adjustment
> 	 is possible."

That's a good question.
He send me a special debug version that gives all registers of the PL2303HX after the plugin.
I think it is better when Frank directly suffer us with his latest version.

Cheers
Karsten

>
> Thanks,
> Johan

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Re: USB to Serial converter code pl2303

[Frank Schäfer]

Am 19.02.2014 18:14, schrieb Johan Hovold:
> On Wed, Feb 19, 2014 at 06:05:54PM +0100, Karsten Malcher wrote:
>> Am 19.02.2014 18:00, schrieb Johan Hovold:
>>> I need an adapter that can handle 2400 Baud to talk to the
>>> ft639/ede639 servo controller chip or possibly a pl2303 driver
>>> that is improved.
>>> The pl2303-driver can handle 2400 baud, but not sure exactly what baud
>>> rates are available for a cloned/pirated pl2303 chip (if that is what
>>> you've got). 115200 baud should be supported, though.
>> We have tested different baud rates with the PL2303HX china clones.
>> All are working including non standard baud rates.
Urgh... Karsten... don't confuse the people. :/
Yes, _your_ clones behave exactly like HX originals, but others don't.

> Ok, good, so 2400 baud should work.
Indeed.
Even the bad clones should support all standard baud rates up o 115200.

>
>> But the non standard baud rates are only available with the modified
>> driver from Frank Schäfer.
> What driver is that? The latest clone-related patch from Frank that I've
> seen stated:
>
> 	"According to Prolific, several (unauthorized) cheap and less
> 	 functional clones of the PL2303HX chip are in circulation. [1]
> 	 I've had the chance to test such a cloned device and it turned
> 	 out that it doesn't support any baud rates above 115200 baud
> 	 (original: 6 Mbaud) It also doesn't support the divisior based
> 	 baud rate encoding method, so no continuous baud rate adjustment
> 	 is possible."
This patch is still 100% valid.
The "good" clones are detected as originals, which is fine.

Regards,
Frank

> Thanks,
> Johan
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Re: USB to Serial converter code pl2303

[Johan Hovold]

On Thu, Feb 20, 2014 at 07:19:13PM +0100, Frank Schäfer wrote:
> Am 19.02.2014 18:14, schrieb Johan Hovold:

> > What driver is that? The latest clone-related patch from Frank that I've
> > seen stated:
> >
> > 	"According to Prolific, several (unauthorized) cheap and less
> > 	 functional clones of the PL2303HX chip are in circulation. [1]
> > 	 I've had the chance to test such a cloned device and it turned
> > 	 out that it doesn't support any baud rates above 115200 baud
> > 	 (original: 6 Mbaud) It also doesn't support the divisior based
> > 	 baud rate encoding method, so no continuous baud rate adjustment
> > 	 is possible."
> This patch is still 100% valid.
> The "good" clones are detected as originals, which is fine.

Good to know. Thanks for clarifying.

Care to respin your refined-device-detection patches against the updated
driver in v3.14-rc?

Thanks,
Johan
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Re: USB to Serial converter code pl2303

[Karsten Malcher]

Am 20.02.2014 19:19, schrieb Frank Schäfer:
>> We have tested different baud rates with the PL2303HX china clones.
>> All are working including non standard baud rates.
> Urgh... Karsten... don't confuse the people. :/
> Yes, _your_ clones behave exactly like HX originals, but others don't.

O.K. - all of them is not correct.
My meaning was all i have tested from the PL2303HX clones.

At least all standard driver only support the standard baud rates.
That's sufficient for nearly all purposes.
But if someone needs to support non standard baud rates, it might be good to know that this is possible with some chips.

Cheers
Karsten
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