Linux stty
stty -F /dev/ttyUSB0 57650 raw
it doesn't like it (invalid argument 57650), it swallows
stty -F /dev/ttyUSB0 ispeed 57650 ospeed 57650 raw
but the output from a subsequent query implies the instructions to change the baud rate &c have been ignored.
Yes, I am logged in as super user.
anyone any ideas?
He who laughs last ... is still using a slow modem
I'd say explain what you're trying to do and on what flavour of linux you're trying to do it
er, set the baudrate of that port and remove "editing" for rx & tx of straight binary data.Originally Posted by frankus
I'd say explain what you're trying to do and on what flavour of linux you're trying to do it
Debian Linux 2.6 on what appears to be a bog stock PC
He who laughs last ... is still using a slow modem
of course I'm assuming I'm referring to the right port!
He who laughs last ... is still using a slow modem
http://ubuntuforums.org/showthread.php?t=1609727
this any use?
yes, it says stty changes a terminal, setserial changes a port. have just done an apt-get install setserial ... need to suss out the parameters to if before I do anything else.
fanx
He who laughs last ... is still using a slow modem
good luck in getting it sorted, I found the unbuntu support pages pretty useful for my issues with sys admining
doh! it helps if you get the port speed right. I was probably rather silly in not checking what my colleague said about the default baud rate, I just used the numbers he gave me but 57600 makes far more sense than 57650! (although the spec doesn't lay restrictions on port speed, its worded so you can set it to whatever you like, which seems plausible so long as the hardware can divide a clock speed down to the number you chose).
Anyway I've set the port speed & stop bits etc, done a
cat file > /dev/ttyUSB0
followed by a
cat /dev/ttyUSB0 > response file
and have definitely got the bytes back in response that the protocol spec says I should have
So now I know I can communicate with the device in this simple manner, all I need to do is write more code that does what's wanted using the relevant techniques
Last edited by musophilr; 22nd January 2013 at 12:44 PM. Reason: accuracy
He who laughs last ... is still using a slow modem
I'm an educated man but this might be the thread that I understand the least, ever. I assume it's about computers but I'm not 100% on that. Just thought I'd share. Kudos to anybody who does get this stuff.
Carry on
The last time I used the program which talked to /dev/ttyUSB0 it did so no trubble. Now, the call to fread blocks for no readily apparent reason. I can see tx/rx lights on the RS485/USB converter box, so I know my commands are being transmitted to the device, and that the device is responding, but its responses are not coming back via the call to fread.
However - and this is probably the cause of it - the PC running Linux has been booted since. The port setup has been lost and I've had to reconfigure it. I know the port speed, character size, and number of stop bits is right, but there's something else I've forgotten to do and I can't remember what!
Funny thing is, the
cat file> /dev/ttyUSB0
works, but the
cat /dev/ttyUSB0 > response file
hangs, so it's not just my program. There's something I've forgotten to do to the port.
Last edited by musophilr; 11th February 2013 at 10:54 PM.
He who laughs last ... is still using a slow modem
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