gene@uicsl.csl.uiuc.edu (04/25/88)
Here are some tips to simplify network wiring for an Appletalk/PhoneNet
system. Logistically, it is similar to the "daisy-chain" configuration
in the User's Guide but is better in three ways: First, it avoids inter-
ception of upstream, or downstream users when an individual Mac is removed;
Second, it avoids the need for RJ11 modular connectors at all interim
stations along the way (i.e., the ones described in the guide); And third,
it conveniently utilizes conventional copper-wire lines such as the unused
black & yellow telephone wires (mentioned in the guide), or abandoned inter-
com wires (i.e. connecting, or splicing is simpler).
To accomplish this, it should be noted that the two receptacles on the
Mac PN208 (or PN209) are simply in parallel. Thus it is only necessary to plug
into one of them with an adapter such as a "VANCO MRP-4" which is a very
compact adapter which converts a RJ11-to-screw terminals for the four wires
in the RJ11. Note that the red and green wires will be ignored by the Mac
(because they may still actually be in use on a telephone line) and we
connect our two-wire line to the black & yellow colors. If you are able to
utilize any obsolete 4-conductor cabling into a room you will use one pair
into the MRP-4, doing a "U-turn" and going back out to the corridor with the
other pair to the point where a main two-wire trunkline was intercepted.
Note that 120 ohm terminating resistors should be used on the beginning
and end of the network. An ordinary 1/4 watt 120 ohm resistor can simply be
included at the MRP-4 black & yellow screws when the line-wires are attached.
If a conventional RJ11 modular plug-connection is needed, such as nearby
units in the same room, it must be plugged in first because of the overhang
of the MRP-4.
One further trick, not to be confused with the above info: If you happen
to have an abandoned Bell-telephone system such as we have on this campus,
you have a windfall of available wiring. (Or if you would prefer to install
modular-type receptacles on the wall near your Mac)...After intercepting
the main two-wire trunk line in the corridor....you connect the red & green
pair in to the wall-mounted modular, and the yellow & black as the return
pair. Now you use a conventional modular extension cord as required to reach
your Mac PN208/209 adapter(plug in first). Now the "VANCO MRP-4" is plugged
into the other recptacle of the PN208/209, but this time the red & green screw
terminals must be jumpered over to the black & yellow pair (e.g. a jumper from
red to black, and a jumper from green to yellow). This simply provides the
required "U-turn" for the signal-path.gene@uicsl.csl.uiuc.edu (04/27/88)
special footnote for uiuc users: see info in "uiuc.general" (ref "B-jacks")