Racal Instruments 1256E, Руководство пользователя

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1256E User Manual
Racal Instruments
©
2002 Computer Interfaces 4-15
operation, and communicating with the 1256 by using a terminal
emulation program.
Equipment Required
To use the RS-232 interface, you need an RS-232 data terminal or
a computer equipped with an RS-232 serial port, such as the COM
port of a personal computer. In addition, a shielded cable is
required for compliance with the radiated emissions standards
specified for the 1256. A shielded RS-232 cable, suitable for
connecting the 1256 to a computer, is available from Racal
Instruments:
RS-232 Cable, 10 feet (3 meters) P/N 602248
DTE Versus DCE
All equipment with an RS-232 interface must be designed as either
Data Communications Equipment (DCE) or Data Terminal
Equipment (DTE), depending upon the end of the communications
link from which it will operate. Computers are usually DTE, and
modems are DCE. This allows a “straight-through” connection,
where connector pins 1, 2, 3, ... at one end connect to pins 1, 2, 3,
... , respectively, at the other end.
The 1256 is designed as DCE to facilitate direct connection to a
computer or data terminal (DTE). Connecting to a modem requires
a “null modem”, described in the section
Connecting to a Modem .
Connecting to a
Computer or Data
Terminal
Electrical Connection
Using a shielded RS-232 cable, connect the nine-pin female RS-
232 connector on the 1256 rear panel to the RS-232 serial port on
the computer or data terminal. Refer to
Figure 4-3, Using the RS-
232 Interface . A suitable cable is available from Racal
Instruments:
•
RS-232 cable, 10 ft. (3.05 meter) P/N 602248
This cable has a DB-9 connector at each end. The male connector
connects to the 1256 and the female connector connects to the
data terminal or computer.
If you wish to make your own cable, Figure 4-4a provides the
details.