Tektronix 2714, Programmer'S Manual, Page: 14 / 308

Introduction to Programming
1–2
2714 & 2715 Programmer Manual
The 2714 or 2715’s RS-232 interface requires a minimum of three signal lines
for operation:
H
Transmit data (TXD)
H
Receive data (RXD)
H
Ground (GND)
If hardware handshake is required, additional lines must be supplied in the cable.
Refer to Appendix A: RS–232 Concepts for cabling diagrams.
The section titled Selecting a Data Flow Control Method on page 1–7 describes
the use of the additional lines for hardware flow control.
EIA Standard RS-232 defines other lines typically used for modem control and
handshaking. The 2714 or 2715 can operate using the minimum wiring
configuration. If the appropriate handshake lines are provided, a printer or plotter
that expects handshaking over the RS-232 interface may be used.
Data bits are transferred serially, one bit at a time, over the RS-232 interface.
Data consists of instrument commands and queries, control settings, parameter
values, or display information.
If a computer is connected to the spectrum analyzer by the RS-232 interface, the
computer’s serial interface (called a COM port if the controller is an MS-DOS
computer) must be correctly configured beforehand. Programmed commands and
data can then be transmitted over the interface to the instrument.
If a query such as
FREQ?
is transmitted, the spectrum analyzer formats its
response immediately and sends it back to the computer. The control program
must be ready to receive the incoming data. In the following subsections you
will learn how to set up your 2714 or 2715 for RS-232 operation. Appendix A:
RS-232 Concepts provides additional information concerning RS-232 imple-
mentation for the 2714 or 2715 including wiring for connectors and null-modem
adapters.