Re: MIDRANGE-L Digest V4 #161

On the back of DSP02 you will have a T connector.  The long leg
will go to the back of the display, and on either side of the
short legs you will have your Baluns.  These are your point of
failures:

1. The baluns are not matched.  That is, the baluns connecting
PRT01 and DSP02 are of different polarities.  As are the baluns
connecting DSP02 to DSP03.  What would happen, the twisted pair
(net work cable) coming from PRT01 to DSP02 gets reversed.  So
when DSP02 tries to use the signal, it is of reversed polarity
so can't use it.  Then when going from DSP02 to DSP03 it gets
reversed again.  So when DSP03 tries to use the signal it can.

2. Over long connections signal strength drops.  This can be
a problem for some devices and not others, depending on how
good their connection is, how new the machine, etc..  Try disconnecting
the Balun on DSP02 that goes to DSP03.  You will most likely have
a switch on the T connector to terminate the connection there.
See if DSP02 comes up then.  If it does come up, consider running
another leg to DSP03.  Using twisted pair (network cables) you
are, theoretically, limited to 1 connection per twinax port.  Anything
more than that and you are getting lucky.  Stuff gets very flaky
beyond that.  Consider buying a twisted pair switch (they make them
for AS/400s).  These hook up the same way ethernet hubs do, each port
serves one terminal/printer, but only requires one twisted pair port
per switch.

3. Maybe DSP02 just doesn't work.  Swap out devices DSP02 and DSP03.
Does DSP03 come up in the new location?  If so, something is not
kosher with DSP02.  If DSP03, which is now in the middle, does
not come up, then something wrong with that location.  Try swapping
the T connector.  Try making sure your baluns are matched on both
ends (same manufacturer.  Different manufacturers set the polarity
different, there is no "standard").

Good luck,

Jim Langston

- ----- Original Message -----
From: Mark Allen <mark.allen@fast-friends.com>
To: MIDRANGE-L <MIDRANGE-L@midrange.com>
Sent: Wednesday, February 14, 2001 10:58 AM
Subject: Display station connection question/issue?


> It's been a long time since I had to deal with this, so if someone can
> tell me what I am doing wrong I would greatly appreciate it.
>
>
> Configuration
>
>
> DSP01-----Twinax cable-----PRT01--Balun--network
> cable--Balun--DSP02--Balun--network cable--Balun--DSP03
>
>
> What happens is that DSP03 gets a signon but DSP02 does not, it stays
> Vary On Pending... All other devices are ok.
>  Any ideas or is this not possible?
>
>
> I have double and triple checked addresses, they are ok.  Have swapped
> network cables with ones I know work and same result. Swapped baluns
> with ones I know work, no diff....
>
>
>
> Mark Allen
> Director of MIS
> Fast Friends, Inc.
> (601) 888-4392 ext. 13
> www.fast-friends.com
>
>
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