|  | Serial I/O problem with pywin32 ? | | |
| | | Xavier |  |
|  Posted: Wed Sep 03, 2008 9:44 am Post subject: Serial I/O problem with pywin32 ? |  |
| |  | |
Hi,
I try to access to a Bluetooth GPS data-logger with Python. I use
pySerial.
Sending and receiving little messages (~100 char) works fine. However,
when I ask the GPS to dump the trails, it returns some Mbytes and here
is the problem : in the stream of bytes, I randomly losts chunks of
~100bytes.
I tried USPP and pyBlueZ instead of pySerial : same problem.
It doesn't like it is a bufferoverun bug from me because :
- the GPS seems to wait when I do not read the stream,
- there is never more than 200 inWainting() characters,
- my code to test it is quite simple :
seriallink = serial.Serial("COM40")
fileName = "data.dump"
out = open(fileName, 'w')
while 1:
c = seriallink.read()
out.write(" %0.2X" % ord(c))
print "*",
out.close()
(with pyBluez :
sock=BluetoothSocket( RFCOMM )
sock.connect(("00:0A:...", 1)))
I tried my program on two different PC with two Bluetooth dongle,
(with pySerial, USPP, pyBluez).
The same things are :
- windows
- the GPS (which works fine with the dumper program of the
constructor)
- pyWin32
I've found another guy with a similar problem :
LINK
He says:
- no problem with little messages
- lost of one byte every hour when receiving a lot of data
Any known problems with pywin32 and serial I/O when downloading a big
stream of data ? |
| |
| | | Diez B. Roggisch | |
| | Posted: Wed Sep 03, 2008 1:33 pm Post subject: Re: Serial I/O problem with pywin32 ? | |
| | | |
Xavier schrieb:
| Quote: | Hi,
I try to access to a Bluetooth GPS data-logger with Python. I use
pySerial.
Sending and receiving little messages (~100 char) works fine. However,
when I ask the GPS to dump the trails, it returns some Mbytes and here
is the problem : in the stream of bytes, I randomly losts chunks of
~100bytes.
I tried USPP and pyBlueZ instead of pySerial : same problem.
It doesn't like it is a bufferoverun bug from me because :
- the GPS seems to wait when I do not read the stream,
- there is never more than 200 inWainting() characters,
- my code to test it is quite simple :
seriallink = serial.Serial("COM40")
fileName = "data.dump"
out = open(fileName, 'w')
while 1:
c = seriallink.read()
out.write(" %0.2X" % ord(c))
print "*",
out.close()
(with pyBluez :
sock=BluetoothSocket( RFCOMM )
sock.connect(("00:0A:...", 1)))
I tried my program on two different PC with two Bluetooth dongle,
(with pySerial, USPP, pyBluez).
The same things are :
- windows
- the GPS (which works fine with the dumper program of the
constructor)
- pyWin32
I've found another guy with a similar problem :
LINK
He says:
- no problem with little messages
- lost of one byte every hour when receiving a lot of data
Any known problems with pywin32 and serial I/O when downloading a big
stream of data ?
|
From my experience with serial lines I'd say: that's the culprit. They
tend to be rather unreliable, as there is no real protocol ensuring data
integrity.
You might consider downloading chunks of data if that's somehow
possible, and re-try failed chunks.
Diez |
| |
| | | Xavier | |
| | Posted: Wed Sep 03, 2008 3:25 pm Post subject: Re: Serial I/O problem with pywin32 ? | |
I tried under Linux... same problem.
So... it may comes from my little lines of code... or from my GPS. |
| |
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