pyserial: failed to readlines() after many hours running.

[zxo102]

Hello All,

I have a system. An instrument attched to 'com1' is wireless connected
to many sensors at different locations. The instrument can forward
the "commands" (from pyserial's write()) to those sensors. Based on
the "commands", the sensors keep sending corresponding data back to
the instrument which wraps up those data and put into "com1" . The
readlines() of pyserial pick up those data for processing.
The data ’string' does not have "\n".

With the following pythong script, if timeout = 0.1, ser.readlines()
in thread1 failed to receive any data after approximate 20 hours. if
timeout=0.5, ser.readlines() in thread1 failed to receive any data
after approximate 60 hours. I am not sure the thread1 was dead or
not. But the whole script did not throw out any error information and
ser.write() in thread2 was ok and kept sending "commands" to com1.

I am testing "timeout = 1" right now, it will probably take more days
to fail to receive data.

Anybody knows how long I should set for "timeout"? Since the data are
from different sensors, I have no idea when they arrive at com1 via
that instrument. If the timeout is set too long, com1 (com1 has
buffer? Sorry, I don't know very much about hardwares) can not have
enough buffer to hold those coming data before ser.readlines() . Or how
does ser.readlines() work?

Should I use readline() instead of readlines()?

Thanks for your any help in advance.

The below is the script:
In thread 1:

import serial, time

ser=serial.Seri al('com1', baudrate=9600, bytesize=8, parity='N',
stopbits=1, timeout=0.1,xon xoff=0, rtscts=0)

while 1:
reading = ser.readlines()
for i in range(len(readi ng)):
if len(reading[i]) 0:
aa = map(ord, reading[i])
bb = ["%02X"%aa[k] for k in range(len(aa))]
# do something here
else:
pass
time.sleep(Read ComSleepTime)
ser.close()

In thread 2:
....
while 1:
...
ser.write("some commands here")
...
time.sleep(30)

Best Regards

ouyang

[Grant Edwards]

On 2008-10-11, zxo102 <zx****@gmail.c omwrote:

I have a system. An instrument attched to 'com1' is wireless connected
to many sensors at different locations. The instrument can forward
the "commands" (from pyserial's write()) to those sensors. Based on
the "commands", the sensors keep sending corresponding data back to
the instrument which wraps up those data and put into "com1" . The
readlines() of pyserial pick up those data for processing.
The data ?string' does not have "\n".

If the data you're reading doesn't contain "\n", then you can't
use readline() or readlines().

--
Grant Edwards grante Yow! I smell a RANCID
at CORN DOG!
visi.com

[Grant Edwards]

On 2008-10-11, Grant Edwards <invalid@invali dwrote:

On 2008-10-11, zxo102 <zx****@gmail.c omwrote:

>I have a system. An instrument attched to 'com1' is wireless
connected to many sensors at different locations. The
instrument can forward the "commands" (from pyserial's
write()) to those sensors. Based on the "commands", the
sensors keep sending corresponding data back to the instrument
which wraps up those data and put into "com1" . The
readlines() of pyserial pick up those data for processing. The
data ?string' does not have "\n".

If the data you're reading doesn't contain "\n", then you can't
use readline() or readlines().

P.S.

To the OP: I normally block postings from google groups (which
is where almost all Usenet spam comes from), so I only saw your
posting because I was experimenting with my spam filtering.
I'll only see additional postings if you post from a real news
server or if somebody who does so quotes one of your postings.

Yes, that sort of sucks. But, until Google shuts off the spam
spigot, you're going to get short shrift if you post from
Google.

There are plenty of free news servers for the text groups like
c.l.p, or you can post to the mailing list via gmane.org.

--
Grant Edwards grante Yow! They collapsed
at ... like nuns in the
visi.com street ... they had no
teen appeal!

[Terry Reedy]

Unknown wrote:

On 2008-10-11, zxo102 <zx****@gmail.c omwrote:

>I have a system. An instrument attched to 'com1' is wireless connected
to many sensors at different locations. The instrument can forward
the "commands" (from pyserial's write()) to those sensors. Based on
the "commands", the sensors keep sending corresponding data back to
the instrument which wraps up those data and put into "com1" . The
readlines() of pyserial pick up those data for processing.
The data ?string' does not have "\n".

Do you have the option of having the instrument insert them between
readings?

>
If the data you're reading doesn't contain "\n", then you can't
use readline() or readlines().

Use .read() instead.

[zxo102]

On 10ÔÂ11ÈÕ, ÏÂÎç11ʱ00·Ö, Grant Edwards <invalid@invali dwrote:

On2008-10-11,zxo102<zxo.. [e-mail] e:

I have a system. An instrument attched to 'com1' is wireless connected
to many sensors at different locations. The instrument can forward
the "commands" (from pyserial's write()) to those sensors. Based on
the "commands", the sensors keep sending corresponding data back to
the instrument which wraps up those data and put into "com1" . The
readlines() of pyserial pick up those data for processing.
The data ?string' does not have "\n".

If the data you're reading doesn't contain "\n", then you can't
use readline() or readlines().

--
Grant Edwards grante Yow! I smell a RANCID
at CORN DOG!
visi.com

But readlines() can read data out of 'com1' for many hours. Maybe I
should try read().

Ouyang

[zxo102]

On 10ÔÂ12ÈÕ, ÉÏÎç1ʱ13·Ö, Terry Reedy <tjre...@udel.. eduwrote:

Unknown wrote:

On2008-10-11,zxo102<zxo.. [e-mail] e:

I have a system. An instrument attched to 'com1' is wireless connected
to many sensors at different locations. The instrument can forward
the "commands" (from pyserial's write()) to those sensors. Based on
the "commands", the sensors keep sending corresponding data back to
the instrument which wraps up those data and put into "com1" . The
readlines() of pyserial pick up those data for processing.
The data ?string' does not have "\n".

Do you have the option of having the instrument insert them between
readings?

If the data you're reading doesn't contain "\n", then you can't
use readline() or readlines().

Use .read() instead.

I can not have the instrument insert "\n" between readings. That is
out of my control. I can try read(). Thanks.

Ouyang