Hello,
I would like to read data comming from two serial port as soon
as they arrive.
I have two devices, one connected to each port. They are sending
data packets sequentially. E.g. device A send one packet then
device B send its packet and so on. Packets can have any length
going from 1 to 30 bytes.
The serial lines have a speed of 4800 baud and packets are
roughly sent every second.
I would like to read packet as they are sent and I want to see
them in the same order they were sent.
Currently, I've written a C program which make use of "select"
to achieve that. The problem is that it is not working in all
conditions.
If packets contain less than 2 bytes and if they arrive slowly,
this is working well. But, if I set the packet sending speed
to one every second, it seems to me that what I'm reading is
only related to the size of the receiving fifo. I'm seeing
packets but they are broken :
data from device A | data from device B
--------------------------------------------
<packet 1A> | \
| <packet 1B> |what I expect and
<packet 2A> | |would like to see
| <packet 2B> /
============================================
<begining of | \
packet 1A> | |
| <packet 1B> |
<end of 1A + | |what I'm getting
begining of 2A> | |
| <begining of 2B> |
<end of 2A> | |
| <end of 2B> /
I've read in the serial-HOWTO that "select" might not be the
most appropriate function to use but I have no idea of another
alternative (I'm writing programs from time to time when it is
required by my job but this is not my primary occupation - so,
I'm lacking some knowledge about the programming API of the
Linux kernel).
Does anybody have an idea about how to do what seemed to me
a simple task (at the begining) ? Or does anybody have any
pointer/links to something that should do this job ?
Thanks in advance for any answer.
Best regards,
Jean-Marie
--
+------------------------------------------------------------+
| Jean-Marie Bussat - Dept. of physics, Princeton University |
| CERN/EP - Bldg. 15-S-012 - CH-1211 GENEVA 23 - Switzerland |
| Email: [EMAIL PROTECTED] |
| Tel: (41 22) 767 32 41 Fax: (41 22) 767 32 41 |
+------------------------------------------------------------+
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