/dev/ttyAMA0 not found when using command line, but when edited in grabserial.py, works fine

[kd5byb]

Good evening!

Was happy to find grabserial - I want to use a Raspberry Pi to log serial data...and grabserial seemed like it would make it easy.

Initially, I couldn't get grabserial to work properly...but figured out how to make it work. I suspect there may be an issue, but I'll admit not being a programmer-type, it is possible that I'm just dumb and this is user error. ;)

First...I obtained grabserial via wget from https://github.com/tbird20d/grabserial/releases/latest which is version 1.8.1.

Second, I un-tar'ed it, then did the install as shown here http://elinux.org/Grabserial:

sudo python setup.py install

Executing grabserial as follows:

grabserial -d /dev/ttyAMA0 -b 19200 -e 30 -t -T -o test.txt

Returns:

Error: serial device '/dev/ttyAMA0' does not exist

(Note: being that this is a Raspberry Pi, I need to not that I've disabled the serial console...and was able to get other scripts to pull data from /dev/ttyAMA0 so I know it exists.)

Looking around on the internet, I saw another user who edited the source with his settings, then executed it with python. So I did the same, downloaded the source and changed the following:

    sd.port="/dev/ttyAMA0"
    sd.baudrate=19200

Now when I execute it with python:

python grabserial.py -e 30 -t -T -o test.txt

Everything works perfectly. I suspect there is something going on with how the /dev/ttyAMA0 is getting passed from the command line into the program?

thanks much, ben, kd5byb

[tbird20d]

---

From: kd5byb notifications@github.com To: tbird20d/grabserial grabserial@noreply.github.com Sent: Sunday, August 23, 2015 3:14 PM Subject: [grabserial] /dev/ttyAMA0 not found when using command line, but when edited in grabserial.py, works fine (#10)

Good evening! Was happy to find grabserial - I want to use a Raspberry Pi to log serial data...and grabserial seemed like it would make it easy. Initially, I couldn't get grabserial to work properly...but figured out how to make it work. I suspect there may be an issue, but I'll admit not being a programmer-type, it is possible that I'm just dumb and this is user error. ;) First...I obtained grabserial via wget from https://github.com/tbird20d/grabserial/releases/latest which is version 1.8.1. Second, I un-tar'ed it, then did the install as shown here http://elinux.org/Grabserial: sudo python setup.py install Executing grabserial as follows: grabserial -d /dev/ttyAMA0 -b 19200 -e 30 -t -T -o test.txt Returns: Error: serial device '/dev/ttyAMA0' does not exist (Note: being that this is a Raspberry Pi, I need to not that I've disabled the serial console...and was able to get other scripts to pull data from /dev/ttyAMA0 so I know it exists.) Looking around on the internet, I saw another user who edited the source with his settings, then executed it with python. So I did the same, downloaded the source and changed the following: sd.port="/dev/ttyAMA0" sd.baudrate=19200 Now when I execute it with python: python grabserial.py -e 30 -t -T -o test.txt Everything works perfectly. I suspect there is something going on with how the /dev/ttyAMA0 is getting passed from the command line into the program? thanks much, ben, kd5byb

Thanks very much for the detailed bug report. I haven't seen this issue, but it's been reported before and I haven't been able to reproduce it. I suspect the problem is in serial.tools.list_ports.comports()

Can you please do the following on your system and send me the results:

At a shell prompt on your host system do: $ python

import serial print serial.tools.list_ports.comports() ^D

$ ls -l /dev/ttyA*

Thanks. -- Tim

[kd5byb]

Hi Tim,

My pleasure:

pi@raspberrypi ~ $ python Python 2.7.3 (default, Mar 18 2014, 05:13:23) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information.

import serial print serial.tools.list_ports.comports() Traceback (most recent call last): File "", line 1, in AttributeError: 'module' object has no attribute 'tools'

pi@raspberrypi ~ $ ls -l /dev/ttyA* crw-rw---T 1 root dialout 204, 64 Jan 1 1970 /dev/ttyAMA0 pi@raspberrypi ~ $

The above started me down the path of perhaps there is a serial.tools package that I don't have. So I did some poking around...and found a post that suggested a slightly different method of listing comports:

pi@raspberrypi ~ $ python -m serial.tools.list_ports no ports found

Very interesting! Not sure what it all means... ;)

thanks much, ben

[kd5byb]

Uh oh...I think I accidently just closed it...

[kd5byb]

Got it back open. Like I said...I'm sort of an idiot... :)

[tbird20d]

OK - I finally got around to providing a workaround for this. I just added a -S option to allow skipping the serial tools device check. This is kind of an ugly hack, but grabserial prints a message suggesting to try this option when it encounters the bug. Hopefully this will guide people to work around the issue.

Sorry this took so long to close. I realize you had a workaround, so it kind of dropped on my priority list. I hope that grabserial is still providing a useful tool for you.