AC7A/B User’s Guide
11
Figure 2-7: 25-Pin to 25-Pin Null Modem Cable Diagram
Figure 2-8: 9-Pin to 25-Pin Null Modem Cable Diagram
To determine whether you have a null-modem or standard cable, perform the following tests:
If you have a cable with 25-pin connectors at both ends
, then test the cable for electrical continuity
between pin 2 on one end of the cable and pin 2 on the other end. These two pins are tied together on a standard
25-pin to 25-pin straight-through cable. In a 25-pin to 25-pin null-modem cable, pin 2 of one end is tied to pin 3 of
the other end.
If you have a cable with a 25-pin connector at one end, and a 9-pin on the other end
, then test the cable
for electrical continuity between pin 2 on one end of the cable and pin 3 on the other end. These two pins are tied
together on a standard 25-pin to 9-pin straight-through cable. In a 25-pin to 9-pin null-modem cable, pin 2 of one end
is tied to pin 2 of the other end.
INSTALLATION
