topic Re: SYS$ASSIGN sends characters to terminal in Operating System - OpenVMS

SYS$ASSIGN sends characters to terminal

Kerry Gibbings — Wed, 20 Jul 2011 11:02:31 GMT

We are communicating with a process control computer via the terminal driver using a TNA device. When the program executes a SYS$ASSIGN, to establish a channel, spurious characters are sent. Can I stop this behaviour, if so how?

I64 OpenVMS 8.3-1H1

TCPIP> show version
HP TCP/IP Services for OpenVMS Industry Standard 64 Version V5.6 - ECO 2 on an HP rx3600 (1.59GHz/9.0MB) running OpenVMS V8.3-1H1

Debug session of BASIC code

─ SRC: module LLBLINKASSIGN -scroll-source────────────────────────────────────────────────────────────────────────────────────────── 118: %PAGE

119: %SBTTL "Main"

120: Exit Function SysStatus If LLBELnkAssign(oLLBLink, SysStatus)

121: SysStatus = SYS$ASSIGN(Trm$(PropGetLLBLink(oLLBLink, "Device")) &

122: ,Chan, !acmode!, !mbxnam!)

-> 123: If SysStatus And 1% Then

124: Call PropLetLLBLink(oLLBLink, "Channel", WordStr(Chan))

125: GoSub LATConnect If PropGetLLBLink(oLLBLink, "Protocol") = "L"

126: Else

127: Subs(1) = Trm$(PropGetLLBLink(oLLBLink, "Device"))

128: Subs(2) = Num1$(SysStatus)─ OUT -output───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────stepped in THREAD 1

LLBLINKASSIGN\LLBLINKASSIGN\SYSSTATUS: 1

LLBLINKASSIGN\LLBLINKASSIGN\CHAN: 816

TCPTrace of packet with spurious characters created as a result of the $ASSIGN

TCPtrace XMT packet 101 at 18-JUL-2011 15:30:51.44

IP Address Port Seq # Ack #

Source 10.123.1.202 62045 481560460 2172722896

Destination 10.123.1.71 2102

Packet Length 46

TCP flags PSH ACK

window 62780

Hex Count Ascii

-------- -------- -------- -------- ---- ----------------

CA017B0A E1B80680 0000E269 2E000045 0000 E...i........{..

D01E8181 8C07B41C 36085DF2 | 47017B0A 0010 .{.G.].6........

03FB FF01FBFF | 00005EE6 3CF51850 0020 P..<.^........

Device is set up as TNA102

show term tna102 /full

Terminal: _TNA102: Device_Type: Unknown Owner: No Owner
Input: 9600 LFfill: 0 Width: 80 Parity: None

Output: 9600 CRfill: 0 Page: 24

Terminal Characteristics:

Interactive No Echo Type_ahead No Escape

Hostsync No TTsync Lowercase No Tab

Wrap Scope No Remote Eightbit

No Broadcast No Readsync No Form Fulldup

No Modem No Local_echo No Autobaud Hangup

No Brdcstmbx No DMA No Altypeahd Set_speed

No Commsync 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 <CTRL-H> Backspace

Re: SYS$ASSIGN sends characters to terminal

Hoff — Wed, 20 Jul 2011 11:43:33 GMT

There is no mechanism to disable this, because this should not happen; sys$assign should not generate any I/O to the output. This looks like a bug (probably) in the IP stack. Patch TCP/IP Services to current and also patch OpenVMS to current, then (if that doesn't clear this) ring up HP support for a look. Or if you're in the typical environment with administrative restrictions around this sort of stuff, ring up HP support first, get (officially) told to patch to current, then (if that doesn't clear this) wait for HP to provide a fix.

Re: SYS$ASSIGN sends characters to terminal

Kerry Gibbings — Wed, 20 Jul 2011 11:56:48 GMT

Thanks Hoff, I must admit I was expecting this response. It took me quite awhile to convince myself that it was sys$assign causing the output. I still don't believe it but have run out of ideas.I did wonder, since the extra characters ends in ETX whether this was some sort of valid control sequence.

We can't go to 8.4 easily but I can get the system updated to the latest VMS and TCPIP patches.

Re: SYS$ASSIGN sends characters to terminal

Volker Halle — Wed, 20 Jul 2011 12:00:44 GMT

Kerry,

how are you creating the TNA device ?

Have you written/used this program on any other version of OpenVMS before or is the a new development ? With other words: did it ever work before ?

Volker.

Re: SYS$ASSIGN sends characters to terminal

Kerry Gibbings — Wed, 20 Jul 2011 12:28:11 GMT

Hi Volker,

That was on my list of things to include, pity I didn't.

$ TELNET/CREATE 10.123.1.71 2102 102/PERM/PROTOCOL=TELNET

$ SET TERM/PERM/TYPEAHEAD/PASTHRU/NOTTSYNC/EIGHTBIT/NOBROAD/NOECHO TNA102:

$ SET SECURITY/CLASS=DEVICE/PROT=(S:RWLP,O:RWLP,G:RWLP,W:RWPL) TNA102:

We've been using this software for 20+ years but have just started to notice the problem when replacing DecServers with IOLAN port servers. We have no proof but think that the DecServers might have filtered this out. It's not causing any harm just causing a delay in the handshaking between the 2 systems, that resync on the second attempt.

Re: SYS$ASSIGN sends characters to terminal

Volker Halle — Wed, 20 Jul 2011 12:37:28 GMT

Kerry,

did you try creating the TNA device with /PROTOCOL=NONE ? Just as a test...

If I understand you correctly, your process control computer now sees 'additional unexpected characters' on it's serial line, after switching from using DECservers to IOLAN port servers.

Sending this call to HP may not yield an immediate solution, as in communication problems, where 2 sides are involved, you may be up to lengthy discussions...

Volker.

Re: SYS$ASSIGN sends characters to terminal

Kerry Gibbings — Wed, 20 Jul 2011 12:58:21 GMT

Thanks Volker,

That stops the extra characters. I have a felling of deja vu now.

Re: SYS$ASSIGN sends characters to terminal

Ph Vouters — Sun, 24 Jul 2011 08:21:21 GMT

Although the code is written in C language, would it be of any help for you ? Refer to TN.C and TN.H at http://vouters.dyndns.org/tima/OpenVMS-GNV-Alternate_DCL_image_using_a_Telnet_device.html with its usage inside DCL.C

Re: SYS$ASSIGN sends characters to terminal

Ph Vouters — Sun, 24 Jul 2011 08:33:48 GMT

Your /PROTOCOL=TELNET initiates a telnet subnegociation with the remote peer. This is why the /PROTOCOL=NONE is better advised if the remote peer does not handle this subnegociation. A excellent to view the sent/received characters is to run the tcpdump utility.. I do advise using tcpdump any time a TCP/IP communication between two peers does not give expected results. For an example of tcpdump usage under OpenVMS can be viewed at http://vouters.dyndns.org/tima/All-OS-Samba-Windows-Sharing-IP_ports_usage_with_Windows_sharing.html In the tcpdump command, you shall to adjust udp ports tracing to tcp ports tracing.

Re: SYS$ASSIGN sends characters to terminal

Kerry Gibbings — Mon, 25 Jul 2011 07:57:06 GMT

Thanks to all. We have now modified the port creation to protocol=none and synchronisation occurs on the first attempt without delay. The messaging protocol between the 2 systems contains it's own error detection so there should be no problems using raw mode.