SUMMARY: Noise or echo on SPIF lines

From: Paul Couzens (PBC.PAUL@MELPN1.Prime.COM)
Date: Mon Apr 05 1993 - 10:24:59 CDT


General consenus was that carrier detect and appropriate cabling would
need to be setup to eliminate the problem. (Problem being due to
noise/linelength/crosstalk). The chips in the SPIF's must be more
sensitive to noise/crosstalk than others I've come across judging from the
responses. Anyway, enabling carrier detect (by turning off softcar) still
did not fix the problem due to the wiring recommended in the SPIF manual,
I had suspicions about it in the first place (Weird config).
I have set up a "proper?" null-modem cable (2-3 crossed, 4-5 crossed, 6-8
off to 20 at the other end and vice-versa) on one of the lines and it is
behaving itself.

receda@chj401.SINet.SLB.COM (Wilson Receda) (Ted Nolan) (Bradford Castalia)
ups!kalli!kevin@fourx.Aus.Sun.COM (Kevin Sheehan) (Mike Daffey)
ups!upstage!glenn@fourx.Aus.Sun.COM (Gelnn Satchell) (Mark Edwards) (Ron Stevens) (Mike Raffety)


   We have a SPARC 10 with 3 x Serial/Parallel Cards (SPIF) that is
exhibiting cyclic logins on the SPIF async lines. The cyclic logins ONLY
appear when the user logs out and turns off the terminal (They turn them
off for fire-risk reasons). The cyclic logins show up as processes
sleeping in idle wait with:

             login -p mkwmouW[}_?oowm

shown with ps -aux. The SAME garbage appears ie., mkwmouW[}_?oowm on all
the logged out, turned off lines. The processes cycle every minute or so -
presumably because of login timeouts. /usr/adm/messages also has:

vmunix: stc_rcvex: unit x line y reciever overrun, char: 0xZZ where x,y
and Z vary.

These appear every hour or so during the night.

Configuration information is: SUNOS 4.1.3
stc board revisions 0x5
stc CD-180 Firmware Revision Level 0x81
stc softint pri 20 driver id V1.2_FCS

Typical /usr/etc/stc/stc_defaults entry:
ttyz06:dtr_assert:soft_carrier: Have also tried dtr_force

ttyy06 "/usr/etc/getty std.9600" wyse50 on local secure

As shipped - #sp9600 Have also tried cons8 (for p8)

/usr/etc/ttysoftcar -a > /dev/null 2>&1

Boards are jumpered for RS232, Sheilded cable, wired as per SPIF manual
p84, length of runs 20 - 100 feet. Terminals are wyse50 and some wyse

Any ideas appreciated,

Paul Couzens,
Melbourne Australia

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