topic Re: Serial port configuration in Operating System - Linux

Serial port configuration

Achilles_2 — Sun, 30 May 2004 22:35:59 GMT

Hi all,

I have configurefd the serail link between two HP A400 servers (for redundancy)

Now I used the echo /cat commands for testing, but after several seconds the 'cat' doesn't display the
messages sent by 'echo' on the other server.

I did three things:
1. I redirected the 'cat' command into a test file;
2. I applied a tusc process on the 'cat' process to see what really took place.
3. I used 'ps -ef | grep tty0p2' to see if another process was susing the device

1. On the text file, apparently there were apparently a lot of "NULL characters" added to the messages characters,
as if another process was using the device (tty0p2), but the ps command didn't show any such process.

2. Apparently, tusc showed that for a while the 'cat' process listened to the msg and wrote them into the log file,
but from time to time it goes 'sleeping' during several seconds.

Could anyone have an idea about configuration of serail link?

Thanks
Alex

Re: Serial port configuration

Mark Grant — Mon, 31 May 2004 07:03:54 GMT

What kind of protocol are you hoping to use on this serial line?

It sound like you are just using it like a "pipe" between the two machines. The most common cause of problems with this kind of config is the cable. I've never done it on a PC but I iamgine you need to at least, swap pins two and three. However there are a host of things you need to be sure are correct. Baud, parity, handshaking etc.

Assuming all these things are correct, I'd try a "sleep 1000 < /dev/ttyS0 &" first too.

Also, have you tried looking into "slip" or "cslip"?

Re: Serial port configuration

Richard Saldivar — Tue, 01 Jun 2004 11:31:17 GMT

As mentioned in the above post the type of cable you need would be a null cable 2-3 crossed, and some hardware pins also. Another type of cable would be the modem type. The type of cable is called DCE to DCE. Computer to computer type of cable. A straight through cable will not work.
Good luck.

Re: Serial port configuration

Dasaradharamaraju — Sun, 13 Jun 2004 04:47:19 GMT

Hi
Try to connect the systems with cable connections :

2 ----> 3
3 ----> 2
4 ----> 6
5 ----> 5
6 ----> 4
7 ----> 8
8 ----> 7

you can leave 1 & 9 pins disconnected.

Regards,
Ramaraju