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Problem on a DS20: baud rate of TTA0 changing without reason

 
Houcmant Philippe
Occasional Advisor

Problem on a DS20: baud rate of TTA0 changing without reason

OpenVMS 7.3-2

We use the serial line tta0 at 600 bps.
Sometimes, we notice that the serial line speed returned to 9600 bps.

We use the same application on 8 DS20, but we notice the problem only on 3-4 servers.

Any idea?
9 REPLIES 9
Steven Schweda
Honored Contributor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

> Sometimes, we notice that the serial line
> speed returned to 9600 bps.

Notice how, exactly?

show terminal tta0

Isn't 9600 normal if it's idle and set to
Autobaud?
Houcmant Philippe
Occasional Advisor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

Application allocates the port at startup and set the baud rate to 600 bps.
The port is allocated permanently by the application.
The port is not in autobaud.
Before reading on the port, we read the speed via a qio.
I know that we can reset the speed to 600 bps at this moment, but it's only a workaround masking the problem.
Ian Miller.
Honored Contributor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

could there be another application or person attaching to the port (could use SHARE priv) and changing the speed?

Are there applications which set port speed to 9600 on the same system?
____________________
Purely Personal Opinion
Houcmant Philippe
Occasional Advisor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

At 2 am (example, it's not always at the same hour), I don't think that a user try to change the speed on these computers.

I don't have the problem on the DS20E.

Patches level is the same on all the servers.
Steven Schweda
Honored Contributor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

> Sep 24, 2010 10:41:19 GMT 0 pts
> Sep 24, 2010 12:42:31 GMT 0 pts

If you didn't want any help, then why ask?

> Application allocates the port at startup
> and set the baud rate to 600 bps.

At system start-up or at application
start-up? Sets the speed how, exactly?

> The port is allocated permanently by the
> application.

What, exactly, does that mean?

> The port is not in autobaud.

> show terminal tta0

Some people might find actual output from an
actual command to be more credible than your
opinion.

> Before reading on the port, we read the
> speed via a qio.

Read how, exactly? IO$_SENSECHAR?
IO$_SENSEMODE?

> At 2 am (example, it's not always at the
> same hour), I don't think that a user try
> to change the speed on these computers.

"I don't think" is hardly evidence of
anything, let alone proof. Have you no batch
queues? I don't think that a change like
this is happening spontaneously, either.

> I don't have the problem on the DS20E.

Then it should be easy to find the difference
between the two systems, right? With
approximately no useful information to work
with, I doubt that any non-psychic here will
be able to find that difference.
John Gillings
Honored Contributor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

SHOW TERMINAL might help

I also have to ask... why 600baud? That's a seriously dark ages speed. Maybe a character printer? LA36 teletype perhaps?

Maybe it's time to consider moving to at least 2 decades ago and upgrade to a console manager?

I'd put an Audit ACE on the terminal device, look for successful updates.
A crucible of informative mistakes
Houcmant Philippe
Occasional Advisor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

Speed is et at the application startup
$ SET TERMINAL TTA0:/PERMANENT/NOBROADCAST/NOTYPEAHEAD/NOTTSYNC/NOWRAP -
/SPEED=(600)/DEVICE_TYPE=UNKNOWN/NOECHO/PASTHRU/EIGHTBIT/PARITY:EVEN

--------------
$ sh term tta0
Terminal: _TTA0: Device_Type: Unknown Owner: NOE_SC2_CNF
Username: NOEMGR

Input: 600 LFfill: 0 Width: 80 Parity: Even
Output: 600 CRfill: 0 Page: 24 Terminate on parity errors

Terminal Characteristics:
Interactive No Echo No Typeahead No Escape
No Hostsync No TTsync Lowercase No Tab
No Wrap Scope No Remote Eightbit
No Broadcast No Readsync No Form Fulldup
No Modem No Local_echo No Autobaud No Hangup
No Brdcstmbx No DMA No Altypeahd Set_speed
No Commsync No Line Editing Overstrike editing No Fallback
No Dialup No Secure server No Disconnect Pasthru
No Syspassword No SIXEL Graphics No Soft Characters No Printer Port
Numeric Keypad No ANSI_CRT No Regis No Block_mode
No Advanced_video No Edit_mode No DEC_CRT No DEC_CRT2
No DEC_CRT3 No DEC_CRT4 No DEC_CRT5 No Ansi_Color
VMS Style Input

--------------
It's an old device accessed every second (read/write).
Steven Schweda
Honored Contributor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

> $ sh term tta0

And what does it look like when the speed has
changed (without reason)?

> [...] /PERMANENT [...]

In my experience, SET TERMINAL /PERMANENT is
pretty durable. Until someone changes it.

> I'd put an Audit ACE on the terminal
> device [...]

Makes sense.
Hein van den Heuvel
Honored Contributor

Re: Problem on a DS20: baud rate of TTA0 changing without reason

Steven wrote
>> Sep 24, 2010 10:41:19 GMT 0 pts
>> Sep 24, 2010 12:42:31 GMT 0 pts
>If you didn't want any help, then why ask?

Hanlon's Razor. "Never attribute to malice that which is adequately explained by stupidity."

This is hist first question here!
Philippe might not know how to properly assign points.

Just like he did not know to provide pertinent information directly with the question.

Philippe... Just 'yanking your chain' as the Americans say. Not calling you stupid. You are doing just fine.

Wish I could help for real, but me thinks that the others are already helping you by asking the right questions to help you focus on a root cause search.

Good luck!
Hein