ASCII TERMINAL HALTS SPARCsta4

ASCII TERMINAL HALTS SPARCsta4

Post by Thom Theriau » Fri, 19 Jul 1996 04:00:00



Headless Sparcstation 4
1).
I plugged in a null modem cable connect to a DEC vt220
into serial a/b port of sparcstation 4 and the system
halted. dead.
First thing I got on the screen was the <ok> prompt.

2).
I rebooted system, everything OK. Did what I had to do,
logged off and I unplugged vt220 from a/b port and the
system halted!

What the heck is going on here??!! I don't believe it's
supposed to bring the system down...from a simple cable
insertion/removal, is it? Any ideas?
TIA
Thom

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Jari Kok » Sat, 20 Jul 1996 04:00:00




>What the heck is going on here??!! I don't believe it's
>supposed to bring the system down...from a simple cable
>insertion/removal, is it? Any ideas?

A break on a serial port console is treated as a L1-A (stop): go to
monitor. A break is the lowering of some signal on the line (DSR,
DTR?). If your console is a terminal on the serial port, you can't
turn it off, or remove the cable without giving a break.

At least this is how it is on a Sun3, but I don't think a SS is
different there.

Jari Kokko

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Brian S. Craigie - Unix SA - NEC - Scotla » Sat, 20 Jul 1996 04:00:00




Quote:> Headless Sparcstation 4
> 1).
> I plugged in a null modem cable connect to a DEC vt220
> into serial a/b port of sparcstation 4 and the system
> halted. dead.
> First thing I got on the screen was the <ok> prompt.

> 2).
> I rebooted system, everything OK. Did what I had to do,
> logged off and I unplugged vt220 from a/b port and the
> system halted!

> What the heck is going on here??!! I don't believe it's
> supposed to bring the system down...from a simple cable
> insertion/removal, is it? Any ideas?
> TIA
> Thom

Yes.  It will crash the machine if it's headless.  On a Sparcserver 1000 we
have, the situation is the same, but it has a key on it you can turn to the lock
position which locks out the serial line input - effectively locks the keyboard
- so you can stop it crahsing.  Unfortunately you don't have a SS1000, so I
don't know how that helps you.  I think there is a way, and an a/b switch might
help - it does with our setup.

Sorry I can't be more positive.

--

Best Regards,

Brian Craigie

Unix Sys Admin

My views are not necessarily those of my employers...

<<< Would sixty gallons be sufficient? -- Robby the Robot >>>

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Jon Kle » Sat, 20 Jul 1996 04:00:00




: >What the heck is going on here??!! I don't believe it's
: >supposed to bring the system down...from a simple cable
: >insertion/removal, is it? Any ideas?
:
: A break on a serial port console is treated as a L1-A (stop): go to
: monitor. A break is the lowering of some signal on the line (DSR,
: DTR?). If your console is a terminal on the serial port, you can't
: turn it off, or remove the cable without giving a break.
:
: At least this is how it is on a Sun3, but I don't think a SS is
: different there.
:
: Jari Kokko

I guess we've all seen this problem using dumb terminals with sparcs...

However, I do NOT see this problem using a Wyse terminal (grr.. I forget
which one exactly), and I do see it on the same machine using a viewpt60.  
I can turn the Wyse terminal connected to my ELC on and off with no apparent
problems.

Anybody care to comment?  What do the Wyse terms do differently?

-jon klein

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Kenneth Cole » Sat, 20 Jul 1996 04:00:00






> : >What the heck is going on here??!! I don't believe it's
> : >supposed to bring the system down...from a simple cable
> : >insertion/removal, is it? Any ideas?
> :
> : A break on a serial port console is treated as a L1-A (stop): go to
> : monitor. A break is the lowering of some signal on the line (DSR,
> : DTR?). If your console is a terminal on the serial port, you can't
> : turn it off, or remove the cable without giving a break.
> :
> : At least this is how it is on a Sun3, but I don't think a SS is
> : different there.
> :
> : Jari Kokko

> I guess we've all seen this problem using dumb terminals with sparcs...

> However, I do NOT see this problem using a Wyse terminal (grr.. I forget
> which one exactly), and I do see it on the same machine using a viewpt60.
> I can turn the Wyse terminal connected to my ELC on and off with no apparent
> problems.

> Anybody care to comment?  What do the Wyse terms do differently?

> -jon klein


Jari is right.  I used to work for a VME sparc manufacturer and we had to put
in special clamping circuit to prevent this from occuring.  I guess that there
are no requirements on power up or power down on the serial lines.  We used
nothing but Wyse terminals and this was always a problem.  Wyse is notorious for
having bad grounding systems along with bad power supply designs.

--
Kenneth Coley
Network Operations Manager
Hybrid Networks, Inc.
408-725-3250 Voice
408-725-2439 Fax

http://www.hybrid.com

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by John Koeni » Sat, 20 Jul 1996 04:00:00


To avoid this, make a serial cable that only passes pins 2,3, and 7
(assuming a DB-25) through.  On the Sun side, connect pin 3 to pin 25
with a large-ish (4.7k /4 watt worked) resistor.  On the terminal side,
strap up any control lines the terminal demands.

This worked great on our SS1000.  It should be a universal fix.




> > Headless Sparcstation 4
> > 1).
> > I plugged in a null modem cable connect to a DEC vt220
> > into serial a/b port of sparcstation 4 and the system
> > halted. dead.
> > First thing I got on the screen was the <ok> prompt.

> > 2).
> > I rebooted system, everything OK. Did what I had to do,
> > logged off and I unplugged vt220 from a/b port and the
> > system halted!

> > What the heck is going on here??!! I don't believe it's
> > supposed to bring the system down...from a simple cable
> > insertion/removal, is it? Any ideas?
> > TIA
> > Thom

> Yes.  It will crash the machine if it's headless.  On a Sparcserver 1000 we
> have, the situation is the same, but it has a key on it you can turn to the lock
> position which locks out the serial line input - effectively locks the keyboard
> - so you can stop it crahsing.  Unfortunately you don't have a SS1000, so I
> don't know how that helps you.  I think there is a way, and an a/b switch might
> help - it does with our setup.

> Sorry I can't be more positive.

> --

> Best Regards,

> Brian Craigie

> Unix Sys Admin

> My views are not necessarily those of my employers...

> <<< Would sixty gallons be sufficient? -- Robby the Robot >>>

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Robert Bono » Sun, 21 Jul 1996 04:00:00






>: >What the heck is going on here??!! I don't believe it's
>: >supposed to bring the system down...from a simple cable
>: >insertion/removal, is it? Any ideas?
>:
>: A break on a serial port console is treated as a L1-A (stop): go to
>: monitor. A break is the lowering of some signal on the line (DSR,
>: DTR?). If your console is a terminal on the serial port, you can't
>: turn it off, or remove the cable without giving a break.
>:
>: At least this is how it is on a Sun3, but I don't think a SS is
>: different there.
>:
>: Jari Kokko

>I guess we've all seen this problem using dumb terminals with sparcs...

>However, I do NOT see this problem using a Wyse terminal (grr.. I forget
>which one exactly), and I do see it on the same machine using a viewpt60.  
>I can turn the Wyse terminal connected to my ELC on and off with no apparent
>problems.

>Anybody care to comment?  What do the Wyse terms do differently?

wrong.   it's the ELC that's different.  it's *NOT* _headless_.

and the 'break to monitor' occurs *only* if the serial port is being used
as the SYSTEM CONSOLE.

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Toomas Tiiv » Mon, 22 Jul 1996 04:00:00



>>supposed to bring the system down...from a simple cable
>>insertion/removal, is it? Any ideas?
>A break on a serial port console is treated as a L1-A (stop): go to
>monitor. A break is the lowering of some signal on the line (DSR,
>DTR?). If your console is a terminal on the serial port, you can't
>turn it off, or remove the cable without giving a break.
>At least this is how it is on a Sun3, but I don't think a SS is
>different there.

Same thing happens also  with Sparcstations 2 and 5, as I have tried.

Only way to avoid Sparcstation going accidentally to monitor, when for
example, You have power interrupt and serial terminal has no UPS, is
to use serial terminal only if it is absolutely necessary. For
example, if You have to login as root and can`t use su. If You try to
use it as ordinary serial terminal for ordinary work, as people
ordinarily do, You will experience the same (unordinarily) BIG
headache I have had before.

Toomas Tiivel

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Jon Kle » Tue, 23 Jul 1996 04:00:00






: >: >What the heck is going on here??!! I don't believe it's
: >: >supposed to bring the system down...from a simple cable
: >: >insertion/removal, is it? Any ideas?
: >:
: >: A break on a serial port console is treated as a L1-A (stop): go to
: >: monitor. A break is the lowering of some signal on the line (DSR,
: >: DTR?). If your console is a terminal on the serial port, you can't
: >: turn it off, or remove the cable without giving a break.
: >:
: >: At least this is how it is on a Sun3, but I don't think a SS is
: >: different there.
: >:
: >: Jari Kokko
: >
: >I guess we've all seen this problem using dumb terminals with sparcs...
: >
: >However, I do NOT see this problem using a Wyse terminal (grr.. I forget
: >which one exactly), and I do see it on the same machine using a viewpt60.  
: >I can turn the Wyse terminal connected to my ELC on and off with no apparent
: >problems.
: >
: >Anybody care to comment?  What do the Wyse terms do differently?
:
: wrong.   it's the ELC that's different.  it's *NOT* _headless_.
:
: and the 'break to monitor' occurs *only* if the serial port is being used
: as the SYSTEM CONSOLE.

wrong.  this also happens on my IPC.  plus, the monitor is broken on the ELC,
so the serial port is being used for the console.

plus, the viewpt60 *will* halt the machine.

-jon klein

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Lyndon Nerenbe » Tue, 23 Jul 1996 04:00:00



>Only way to avoid Sparcstation going accidentally to monitor, when for
>example, You have power interrupt and serial terminal has no UPS, is
>to use serial terminal only if it is absolutely necessary. For
>example, if You have to login as root and can`t use su. If You try to
>use it as ordinary serial terminal for ordinary work, as people
>ordinarily do, You will experience the same (unordinarily) BIG
>headache I have had before.

My (fuzzy) memory of this is the machine halts to the monitor if
CD drops on the console serial port. The solution is to jumper
the connector on the Sun to ensure CD is always asserted. (I.e. tie
it to DSR -- no UPS required :-)

--lyndon

--
Orthanc Systems -- Internet and UNIX consulting -- Prince George, B.C
_____________________________________________________________________

                      http://www.orthanc.com/

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Tor Hought » Wed, 24 Jul 1996 04:00:00


: I guess we've all seen this problem using dumb terminals with sparcs...

: However, I do NOT see this problem using a Wyse terminal (grr.. I forget
: which one exactly), and I do see it on the same machine using a viewpt60.  
: I can turn the Wyse terminal connected to my ELC on and off with no apparent
: problems.

: Anybody care to comment?  What do the Wyse terms do differently?

Uhm. They _don't_ atleast not the ones we _were_ (notice the past tense? :)
using here. The model number was: WY-120, which caused our SS20's to halt
when it was unplugged. One of them also developed a fault, which also caused
the machine to halt at irregular intervals.

Tor Houghton
Telenor Online AS

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Scott Penn » Thu, 25 Jul 1996 04:00:00


: Headless Sparcstation 4
: 1).
: I plugged in a null modem cable connect to a DEC vt220
: into serial a/b port of sparcstation 4 and the system
: halted. dead.
: First thing I got on the screen was the <ok> prompt.

: 2).
: I rebooted system, everything OK. Did what I had to do,
: logged off and I unplugged vt220 from a/b port and the
: system halted!

: What the heck is going on here??!! I don't believe it's
: supposed to bring the system down...from a simple cable
: insertion/removal, is it? Any ideas?
: TIA
: Thom

Thom,

        We had this same problem with our S20 servers at my last site.  
We found that if you insert a resistor (I don't remember what ohm) on the
line this will keep the break signal from reaching the serial port,
and thus end the problem.  

        I'll try to find out the specific resistor to use and best placement
for it..

Scott P.

-___  ____ __
| _ \/ __/|  \  Scott M. Penney - At Chrysler/Tivoli

|_|  /___/|_|__\  Office: (810) 758-9533  Pager: (800) SKYPAGE #249-2262
        "I'd rather be rich than stupid." - Jack Handey of SNL

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Kjetil Torgrim Hom » Thu, 25 Jul 1996 04:00:00


[John Koenig]

|   To avoid this, make a serial cable that only passes pins 2,3, and
|   7 (assuming a DB-25) through. On the Sun side, connect pin 3 to
|   pin 25 with a large-ish (4.7k /4 watt worked) resistor. On the
|   terminal side, strap up any control lines the terminal demands.

That's funny, on our SS20s, I can unplug or replug the serial console
without sending a BREAK. Turning off the terminal while it is
connected on the other hand, will drop the computer into the boot
prom. We use old Tandberg TDV2230 as consoles.

The cable we use is simple, 2-3 swapped, the rest go straight through.

Kjetil T.

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Mike Skell » Fri, 26 Jul 1996 04:00:00



> Headless Sparcstation 4
> 1).
> I plugged in a null modem cable connect to a DEC vt220
> into serial a/b port of sparcstation 4 and the system
> halted. dead.
> First thing I got on the screen was the <ok> prompt.

> 2).
> I rebooted system, everything OK. Did what I had to do,
> logged off and I unplugged vt220 from a/b port and the
> system halted!

> What the heck is going on here??!! I don't believe it's
> supposed to bring the system down...from a simple cable
> insertion/removal, is it? Any ideas?
> TIA
> Thom

The simple answer is to fake the modem conditions, just look at the
connections that your interrace has, ie v.24 signals of rs423 etc,
fake out the modem signals to high, and disable software flow control of
the terminal. Disconnect the modem control signals from the terminal.
The workstation is now not aware of the connection or disconnection of
the terminal

The disable of flow control is vital as this diables the possibility of
the terminal being disconnected just after the sending of XOFF which
will eventaully crash the system, as the messages queue up

There are a number of companies that sell a kit to enable you to fake
connections, and some may have a plug that copes with these requirements
already (as this is a standard problem)

--
Mike Skells     +44 1473 224461
The views expressed here are personal and do not represent
the views of the company that I work for

 
 
 

ASCII TERMINAL HALTS SPARCsta4

Post by Earl Barfie » Fri, 26 Jul 1996 04:00:00



>: 1).
>: I plugged in a null modem cable connect to a DEC vt220
>: into serial a/b port of sparcstation 4 and the system
>: halted. dead.
>: First thing I got on the screen was the <ok> prompt.
>: 2).
>: I rebooted system, everything OK. Did what I had to do,
>: logged off and I unplugged vt220 from a/b port and the
>: system halted!
>: What the heck is going on here??!! I don't believe it's
>: supposed to bring the system down...from a simple cable
>: insertion/removal, is it? Any ideas?
>    We had this same problem with our S20 servers at my last site.  
>We found that if you insert a resistor (I don't remember what ohm) on the
>line this will keep the break signal from reaching the serial port,

The trick here is to either prevent the computer from ever seeing low
dtr on the port or configure the computer to ignore low dtr on the
port.  

Leaving the terminal on all the time is one way.  When that's not
possible, be sure to disconnect the serial cable before you power off
the terminal and power the terminal back on before you reconnect the
serial cable.  The reason that this works is because ttl logic usually
floats to "high."  Therefore, no connection is seen as a "high" on "on"
condition.  Only when the port is connected to an unpowered console is
the signal pulled "low."  You can also use a resistor to pull dtr
high.

By far the easiest fix is to set the computer to ignore dtr.  This
works on sparc 10/20/5s and most any other sparc with a recent eeprom.
I'm not sure if the eeprom in the Sparc Server 4/490 and 4/6xx
computers support this.  On a sparc 20, you set 'ttya-ignore-dtr=true'.
See 'man eeprom' to see how to set this.  From a root ksh or sh, you
can type 'eeprom ttya-ignore-cd=true'.  At the boot "ok" prompt, you
can type 'setenv ttya-ignore-cd true'.   You can check all the eeprom
settings by typing 'eeprom' at a shell prompt or 'printenv' at the
boot "ok" prompt.

--
Earl Barfield  --  Operations Department / Information Technology  
Georgia Institute of Technology, Atlanta Georgia, 30332


 
 
 

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