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NXU-2 Operations Manual
2-9
JPS Communications, Inc.
2.8.5.1 Connecting Equipment and Computers to an NXU-2
The RS-232 serial cable supplied with the NXU-2 is a straight-through cable used to connect
the NXU-2 to a PC serial port. In order to connect the NXU-2 port to an ACU-1000, you need
a DB-9 male-male null modem cable, also called a crossover cable.
RS-232 serial devices are divided into two types. Devices, which provide control information,
are called DTE (Data Terminal Equipment) devices. Devices, which accept control
information, are called DCE (Data Communication Equipment) devices. In the "old days”, the
DTE devices were terminals and computers, while the DCE devices were modems and
equipment. The RS-232 standard specified that DTE devices would connect to DCE devices
using a straight-through cable. If you wanted to connect two like devices (DTE to DTE or DCE
to DCE) then you needed a null modem (crossover) cable. The PC is a DTE device, and the
NXU-2 and ACU-1000 are DCE devices. That is why you need a crossover cable for
connecting an ACU-1000 to an NXU-2. The following drawing shows typical cable
requirements for connecting different devices to an NXU-2. See Figure 2-4
DTE Versus
DCE Serial Cables.
LAN, WAN
Or T1
RS232
Straight
Through
Cable
RS232
Null
Modem
Cable
RS232
Null
Modem
Cable
RS232
Straight
Through
Cable
RS232
Null
Modem
Cable
DTE
Device
DTE
Device
DTE
Device
DCE
Device
DCE
Device
DCE
Device
COMP
NXU-2
NXU-2
ACU-1000
J4
J4
DTE
Device
DCE
Device
DCE
Device
DCE
Device
Figure 2-4
DTE Versus DCE Serial Cables
Summary of Contents for NXU-2
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