20 Mar
2001
20 Mar
'01
9:52 p.m.
On Mar 21, 7:39, Arno Kletzander wrote:
we're running a *small* network consisting of two
Sun SPARCstations (1+
and
2) and a CalComp CCS600 ES laser printer. They're
all connected to
"Transceivers" with 15-pin Sub-D connectors on them which sit along a
yellow cable
(approx. 10mm = 4/10" in diameter). AFAIK this
concept is called "Thick
Ethernet"
(IEEE 802.3), am I right?
Yes, that's right.
we've put another transceiver on the cable
strictly according to the
installation guide that came with it (drilling hole into cable with
recommended tool etc...).
Since we've done that, it's no longer possible to print from one of the
SUNs to the CalComp although the PC is not yet connected to the
transceiver.
The whole assembly looks somewhat like this:
TermRes _______ _______ _________ _______
TermRes
I-------I TC1 I------I TC2 I------I TC3
I------I TC4 I------I
I I I I
SUN 1+ SUN 2 CalComp (planned) PC
It sounds like you've shorted the cable. Do those transceivers have a set
of LEDs on them? I suspect not, but that might tell you if anything is
being transmitted/received. You could try removing one terminator and
testing the DC resistance between core and shield of the coax; it should be
50 ohms with nothing powered up.
If you have shorted it, the best solution is to cut out the damaged part,
fit an N-series plug to both ends, and put a coupler between them. Or,
instead of a coupler, a transceiver with N-series connections (which are
more common and cheaper than vampire taps anyway). Another way is to
discard some or all of the thick coax, and use thin coax with BNC
connectors instead. Then you use BNC T-pieces to connect to miniature
transceivers, which are fitted directly to the 15-pin sub-D AUI connectors
on the backs of the machines, with no bulky drop cables. You can get
N-to-BNC adaptors and BNC terminators for pennies.
--
Pete Peter Turnbull
Network Manager
Dept. of Computer Science
University of York