User's Manual

Table Of Contents
Installation
33
PTU to Host Cabling
RJ45 to DB25 Adaptor
To connect the 100baseT cable to the AC Shelf interface panel a RJ45 to DB25 adaptor must
be fitted. Fit the RJ45 to DB25 adaptor and screw to the backplane. The RJ45 to DB25
adaptor currently must be connected onto the lower of the two 25-way AC connectors
allocated to each slot (even though the activity lights work if connected to the top).
Patch Cable
A standard Cat 5 Ethernet patch cable with 8-way RJ45 plugs at each end has all pins
connected straight through. The Tx and Rx pairs are pins 1&2 and 3&6. With plug towards
you, cable away from you, pins on the top, pin 1 is on your right. Clearly Tx at one end must
talk to Rx at the other.
A Hub (and Router) Ethernet port will have a built in crossover, often denoted by a ‘X’ printed
on the box, so a PC to a Hub uses a straight through standard patch cable, and so does a
Router to the PTU.
To connect a PC to PC or a PC to PTU (for demo, tests, etc.), use a crossover cable, with Pin
1 to Pin 3 and Pin 2 to Pin 6.