Issue #049 [Fixed/closed] - Serial Monitor Input Field not updating - solution included

Posted by Marcus.Barkowsky

What steps will reproduce the problem?

  1. Continuously sending from the Gertboard's Atmel to the Raspberry
  2. Opening https://.../app/serial-monitor
  3. The input of the serial port does not show up though sending works (i.e. the config file has ttyAMA0 enabled and webiopi was called with the -c <configfile> switch)

WebIOPi version used? => Latest git read-only checkout version as of 09/05/2013

Python version used? => Python 2.7.3 (default, Jan 13 2013, 11:20:46) [GCC 4.6.3] on linux2

Distro used? (WebIOPi has only been tested on Raspbian Wheezy) =>

Raspberry Pi board revision? (1 or 2) => 2

For Javascript side bugs, Browser? => firefox, linux

Please provide any additional information below.

The response type for GET in the read function has not been defined, therefore the function returned an XML Document instead of a file. Adding

from import request, response

and the @response line in:

@request(&quot;GET&quot;, &quot;&quot;)
def read(self):

Solves the problem. Attached, the changed file.

Thanks for your great work on webiopi!

Files attached

Comment 1

Posted by dt.photoclix

Hi, First of all, thank you very much for your great product.

Second : even after making this change, I still can't get my Serial-Monitor to show me the serial data that comes in.

Any ideas on what I would need to check ?


Comment 2

Posted by Marcus.Barkowsky


it is difficult to judge your progress in debugging from your question. So, unfortunately, I can only explain how I tackled the problem.

Before trying with webiopi, I made sure that my serial communication worked flawlessly with the terminal program "minicom" and that I was also able to read/write with simple "cat" commands after the serial interface was configured (baudrate, parity, etc.). It's some time ago, so I do not remember whether I changed something in the /etc/webiopi/config configuration file (I definitely activated the serial0 line) and/or changed the permissions on the /dev/ttyAMA0 (I started by launching the project as root anyway). For further debugging, I launched webiopi as foreground process and started debugging by adding"message") lines in the python code to see where the problem might be located.

Best regards, Marcus

Comment 3

Posted by dt.photoclix

Hi Marcus,

Thx for your input. I already double checked the serial communication and have even built code for 2 status-leds that react differently, depending on which command the RPi receives back via serial-connection. All of this works perfectly.

Yesterday, I was testing my interface on my smartphone, which uses Dolphin-browser and by coincidence I noticed that the Serial-monitor field, which I adapted a bit to my own interface (just formatting and size) was working just fine. It nicely displayed all information, I expected to be there. Went back to my PC and laptop, opened FireFox, but it still didn't work. Opened up IE on both and it worked just nicely. I've been a FireFox user since the first moment, and this is one of the first times that I run into a problem, where something doesn't work on FF but it works on IE. Will have to look into that.

Best regards,


Comment 4

Posted by DC4PCqrv

Hi David, I experienced the same problem with ttyUSB0. In my environment, IE uses the so called compatibility mode by default. FF interprets the first line of an html file very strictly – at least I didn't find any compatibility settings, because it was too late at night or in the morning or so. Hence, I decided to have a closer look at the jquery environment. Looking at the distributed jquery.js I found out it is a rather outdated version 1.8.2 (for some pretty good reasons I think). May be it's a good idea to apply some updates … I used sudo nano /etc/webiopi/config to make some changes to use my private test environment:



HTTP Server configuration

enabled = true port = 8000

File containing sha256(base64("user:password"))

Use webiopi-passwd command to generate it

passwd-file = /etc/webiopi/passwd

Use doc-root to change default HTML and resource files location

doc-root = /home/pi/WebIOPi-0.6.0/htdocs

Use welcome-file to change the default "Welcome" file

welcome-file = index.html










USB serial adapters

usb0 = Serial device:ttyUSB0 baudrate:9600

usb1 = Serial device:ttyACM0 baudrate:9600





end of /etc/webiopi/config changes

The following files were downloaded from sections jQueryCore and jQueryMobile, copied to /home/pi/WebIOPi-0.6.0/htdocs on the PI and renamed accordingly later. The original files were deleted - you may want to backup them before deletion :-) for any purpose => jquery-mobile.css => jquery-mobile.js jquery-2.0.3.min.js => jquery.js

Now I stopped and restarted the WebIOpi service sudo /etc/init.d/webiopi stop sudo /etc/init.d/webiopi start

The serial monitor works now fine with IE 10.0.9200.16660 and FF 23.0.1 both under Win7. However, there are some more back-compatibility drawbacks and issues according to Watch this carefully! I didn't test more because it does the job in my environment :-) so it's up to you to do more ... May be this helps to solve the other serial issues too

Best regards


Comment 5

Posted by trouch

I admit I tested the Serial Monitor only with Chrome.

Comment 6

Posted by trouch

Comment 7

Posted by trouch

Comment 8

Posted by trouch

Issue 79 has been merged into this issue.

Comment 9

Posted by trouch

This issue was closed by revision r1412.