NXU-2A Operations Manual
Interoperability Now!
2-9
2.8.5
Serial Port Connection, J4
J4 is a standard RS-232 DCE serial port. It is a female DB-9 connector, and can be interfaced to
most PCs, typically standard DTE serial ports, using the DB-9 straight-through serial cable
included with the NXU-2A.
Table 2-3
J4 Serial Port Pinout
J4 pin
Description
2
TX data
3
RX data
5
Ground
2.8.6
Connecting Equipment and Computers to an NXU-2A
The RS-232 serial cable supplied with the NXU-2A is a straight-through cable used to connect
the NXU-2A to a PC serial port. In order to connect the NXU-2A 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. 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-2A and ACU-1000 are DCE
devices. That is why you need a crossover cable for connecting an ACU-1000 to an NXU-2A.
The following drawing shows typical cable requirements for connecting different devices to an
NXU-2A. See Figure 2-4 DTE Versus DCE Serial Cables.
Содержание NXU-2A
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