Serial-USB

qwerty_face

Hi all,

I'm running Ubuntu 10.4. My serial-USB cable is giving me some jip. Well, specifically it does recieve stuff since Cutecom prints to the screen. Maybe I am doing something wrong but I am afterall a newbie. Anyway I was hoping that somebody on the forum would be able to figure this out.

Basically, I got the cable off eBay and it came with all the usuals. The software on the CD though is garbage (it doesn't even work in Windows Vista let alone Linux) and the company name does not resolve to any identifiable business online - what business does not own a website nowadays...

Plus, even when Windows detects software for it, it does not properly install and it just will not work. So that's Windows and I am fed up with bothering with it under that platform.

Linux says the hardware of the adapter is a PL2303. There are some known issues with the PL2303 and PL2303X hardware, but I AFAIK that has been long resolved with a patch to the old driver in the current 2.6.x Linux kernel:

Prolific PL-2303X - Ubuntu Forums

Some searching about on Google shows how somebody can get the adapter running with registering the device with modprobe from the terminal:

Ubuntu USB-Serial port install procedure

I gave that a go, and now have the cable registering and being assigned to ttyUSB0.

First here are my console outputs:

Before plugging in the cable:

% dmesg | tail
[ 1366.483444] wlan0: RX AssocResp from 00:16:b6:da:69:05 (capab=0x411 status=0 aid=1)
[ 1366.483449] wlan0: associated
[ 1366.484391] ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[ 1376.572036] wlan0: no IPv6 routers present
[ 2443.905032] CE: hpet increasing min_delta_ns to 15000 nsec
[ 5075.081074] CE: hpet increasing min_delta_ns to 22500 nsec
[ 5075.081146] CE: hpet increasing min_delta_ns to 33750 nsec
[ 6602.166470] psmouse.c: TouchPad at isa0060/serio1/input0 lost sync at byte 4
[ 6602.168480] psmouse.c: TouchPad at isa0060/serio1/input0 lost sync at byte 1
[ 6602.177432] psmouse.c: TouchPad at isa0060/serio1/input0 - driver resynched.

After plugging in the cable:

% dmesg | tail
[ 6844.100783] usb 3-1: configuration #1 chosen from 1 choice
[ 6844.179945] usbcore: registered new interface driver usbserial
[ 6844.179989] USB Serial support registered for generic
[ 6844.180076] usbcore: registered new interface driver usbserial_generic
[ 6844.180082] usbserial: USB Serial Driver core
[ 6844.199707] USB Serial support registered for pl2303
[ 6844.199779] pl2303 3-1:1.0: pl2303 converter detected
[ 6844.231808] usb 3-1: pl2303 converter now attached to ttyUSB0
[ 6844.231858] usbcore: registered new interface driver pl2303
[ 6844.231865] pl2303: Prolific PL2303 USB to serial adaptor driver

As you can see, everything registers fine and the module is assigned to ttyUSB0. Now from this point on it is much easier to show you what my problem is as opposed to describing it. So the following are screenshots of Cutecom's output when I connect the cable to a Cisco RJ45-DB9 cable which is itself plugged into the console port of my 2620XM:

When I switch on the router and click "open device" in cutecom I get this:

http://img409.imageshack.us/img409/3421/66949759.png

When I type 'ver' as a command in Cutecom I get this:

http://img690.imageshack.us/img690/1659/95351751.png

Any ideas? If not can you recommend a decent USB-Serial cable that is not the PL2303/2303X hardware?

tiersten

You sure your router is set to 9600? It is the default but somebody might have changed it. Have you tried a different router/switch? A different console cable?

PL2303 based adapters are fine. I've got several here along with FTDI based ones and I've never had any problems with them under Windows, Linux or OSX.

ziggi138

What i do for my usb-serial cable in linux is, I open Tilda (or any terminal window you want to use) and type screen /dev/serial/by-path/ then i press the tab key and it auto fills the info i need. make sure your device is on and you have the usb-serial cable plugged in along with the console cable hooked up to the console port and the serial end in the serial-usb adapter.

This is what works for me. Your results may vary. Hope this helps.

peanutnoggin

I'm using an Elecom USB-to-Serial adapter with Ubuntu 10.4. It's working just fine. Try using putty as your terminal emulator:

Once you get putty, you can then click the serial button, ensure 9600 is selected and tell it the usb device is: /dev/ttyUSB0

HTH.

-Peanut

qwerty_face

tiersten wrote:

You sure your router is set to 9600? It is the default but somebody might have changed it. Have you tried a different router/switch? A different console cable?

I have a 2610XM, 2620XM and 2621XM and each are showing this same result.

ziggi138 wrote: »

...make sure your device is on and you have the usb-serial cable plugged in along with the console cable hooked up to the console port and the serial end in the serial-usb adapter.

It is plugged in all the right places, and as you can see by the dmesg output above, my linux box recognises the cable and assigns it to an appropriate getty.

peanutnoggin wrote: »

I'm using an Elecom USB-to-Serial adapter with Ubuntu 10.4. It's working just fine. Try using putty as your terminal emulator:

Once you get putty, you can then click the serial button, ensure 9600 is selected and tell it the usb device is: /dev/ttyUSB0

HTH.

-Peanut

When I hit open device in Putty under the serial tab, nothing happens. Don't know what that's all about... Perhaps I'll buy one of the Elecom devices.

peanutnoggin

qwerty_face wrote: »

When I hit open device in Putty under the serial tab, nothing happens. Don't know what that's all about... Perhaps I'll buy one of the Elecom devices.

Once you click open, you're not getting a black screen? If you do get the black screen, it'll either error or let you into your device. You may have to hit enter a few times before you see anything. Lastly, are you sure you're using the Console port and not the AUX port? Not trying to insult your intelligence, but I've done before and I only ask because other factors seem to be correct. HTH.

-Peanut

qwerty_face

peanutnoggin wrote: »

Once you click open, you're not getting a black screen? If you do get the black screen, it'll either error or let you into your device. You may have to hit enter a few times before you see anything. Lastly, are you sure you're using the Console port and not the AUX port? Not trying to insult your intelligence, but I've done before and I only ask because other factors seem to be correct. HTH.

-Peanut

No, no black screen from Putty. And still wont bring up a terminal or whatever it is supposed to after I hit open device.

No worries, that's what troubleshooting is all about - it is certainly in the console part.

Something that was said earlier about the speed that the routers might be set to could be different from 9600baud. How likely is it that all three are changed to a higher baud rate and is there a way to get them to default bearing in mind that I cannot send commands over serial cable?

Do I have to symbolically link ttyUSB0 to ttyS0 (of which is the default serial interface in Putty) ?

chmorin

qwerty_face wrote: »

Something that was said earlier about the speed that the routers might be set to could be different from 9600baud. How likely is it that all three are changed to a higher baud rate and is there a way to get them to default bearing in mind that I cannot send commands over serial cable?

Do I have to symbolically link ttyUSB0 to ttyS0 (of which is the default serial interface in Putty) ?

Considering you got the device from ebay, anything is possible. Different parts of the world use different serial speeds. 38400 is an example of another possible one. The output you are seeing is usually seen when you are receiving data but the terminal does not know how to interpret it. Could be a driver issue, but could also be the speed.

qwerty_face

Problem now solved - I recieved another that I ordered a couple of days ago.

Interestingly, it is the same hardware as the other one (PL-2303X) and works fine. I think the other one must have had faulty internals.

Cheers all.

tiersten

qwerty_face wrote: »

Interestingly, it is the same hardware as the other one (PL-2303X) and works fine. I think the other one must have had faulty internals.

The other one is faulty. Prolific chip based USB serial adapters work fine and don't require any firmware uploads unlike some other chips. The only requirement is that you have their driver installed but that is widely available and supported on all major operating systems.