Modem does not answer if conntection is closed without exit command

[dandec]

Hi all,
I'm a new HP user. I've a problem with a modem used for remote connection.
When I disconnect from the terminal using the "exit" command, the connection is closed properly and than I can connect again to the server.

If I close the connection without "exit", then the modem does not answer to the next calls.

Did you have any idea about this problem?

Thanks in advance for your help.

[Steven E. Protter]

Shalom,

Suspect the modem hardware.

Try reconfiguring with sam prior to having the modem replaced.

SEP

[dandec]

Hi Steven,
I will try it, but I'm not sure that I can open the sam interface, because I've only remote connection by modem and I'm not sure that SAM work properly by console.


Thanks,
Daniele

[Matti_Kurkela]

Apparently either the modem does not detect the loss of connection in a timely fashion (or at all) or does not manage to signal the fact to the server. The last one is the most likely.

The cause might be the modem, the cable or the server.

What kind of a serial cable cable is there between the server and the modem? Does it have only 3 wires (bad) or all 9 required to transmit all the control signals (good)? Without knowing the type of the cable, it is impossible to determine the correct settings for both the modem and the server.

What kind of remote connection it is? Is it just an ordinary terminal connection, or a remote console?

(If you can connect to the server and see some status information even if the server's operating system is not running, it's a remote console. With it, you can usually send a reset signal to the hardware to re-start the OS.)

Try to find the documentation for your modem. There are enough subtle differences in different modem models that changing the modem configuration without the appropriate documentation is likely to be very difficult.

When there is a connection, the modem should output a DCD (Carrier Detect) signal to the server (this is configurable in the modem). When the connection is lost for any reason, the modem should drop this signal. The serial port driver in the server OS should be configured to recognize this (configurable in the server).

If there is a session active when the carrier is lost, the OS will send a HUP (hangup) signal to all the processes belonging to that session. Most user processes will abort when they receive that signal, but a process can do some things before aborting or even ignore the signal completely, if it's programmed to do so.


With a remote console, there is a separate "service processor" controlling the connection on the server side. Usually the service processor's modem connection is not very configurable, so you'll need to adapt the settings of your modem to the requirements of the service processor.
Find the documentation of your server from docs.hp.com (or from www.openpa.net if it's very old).

If it's an ordinary terminal connection (using a MUX card or a plain serial port), you can use "stty -a" while you're connected through the modem to view the server side settings. The "man stty" command will give you more information about the stty command and its many settings.

Getting the modem settings while using the modem connection is very tricky and prone to errors. I'm afraid you'll have to be on site to check the modem configuration.

MK

[dandec]

Hi Matti,
thank you for your feedback and sorry for my late answer, but I was out of office. Now I'm back again with this problem.

Below the answer to your questions:

- This is the cable schema

D 9 pin F (server) D 25 pin M (modem)

S -------------------------- S - 1
1 -------------------------- 8
2 -------------------------- 3
3 -------------------------- 2
4 -------------------------- 20
5 -------------------------- 7
6 -------------------------- 6
7 -------------------------- 4
8 -------------------------- 5
9 -------------------------- 22



- the connection is a ordinary terminal connection. the getty command in the inittab is :

a0:234:respawn:/usr/sbin/getty -h -t 40 -h ttyd1p2 19200m

- from gettydefs

#
# This entry is for high speed modems. Most of these tend to always
# communicate to the cpu at 19200, regardless of the connection speed.
#

19200 # B19200 HUPCL IGNPAR PARENB ICRNL IXON OPOST ONLCR CS7 CREAD
ISIG ICANON ECHO ECHOK PARENB ISTRIP IXANY TAB3
# B19200 SANE CS7 PARENB ISTRIP IXANY TAB3 HUPCL
#login: #19200

19200m # B19200 HUPCL OPOST CS8
# B19200 HUPCL SANE CS8 IXANY TAB3
# Please login(19200): #19200m



- modem is :modem HP mt5634zba



- stty -a :

smsc1:root> stty -a
speed 19200 baud; line = 0;
rows = 0; columns = 0
min = 4; time = 0;
intr = ^C; quit = ^\; erase = ^H; kill = ^U
eof = ^D; eol = ^@; eol2 = ^@; swtch = ^@
stop = ^S; start = ^Q; susp ; dsusp
werase ; lnext
-parenb -parodd cs8 -cstopb hupcl cread -clocal -loblk crts
-ignbrk
ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl -iuclc
ixon ixany ixoff -imaxbel -rtsxoff -ctsxon -ienqak
isig icanon -iexten -xcase echo echoe echok -echonl -noflsh
-echoctl -echoprt -echoke -flusho -pendin
opost -olcuc onlcr -ocrnl -onocr -onlret -ofill -ofdel -tostop
smsc1:root>






Thanks
Dan