Section 2: General operation
Model 2657A High Power System SourceMeter® Instrument Reference Manual
2-90
2657A-901-01 Rev. B/December 2012
RS-232 connections
Connect the RS-232 serial port of the Model 2657A to the serial port of a computer using a straight-
through RS-232 cable terminated with DB-9 connectors. Do not use a null modem cable. The serial
port uses the transmit (TXD), receive (RXD), CTS and RTS (if flow control is enabled), and signal
ground (GND) lines of the RS-232 standard. The connector location is shown in
(on page 2-79).
If your computer uses a DB-25 connector for the RS-232 interface, you will need a standard cable or
adapter with a DB-25 connector on one end and a DB-9 connector on the other. An RS-232 cable is
available from (
http://www.keithley.com
).
Figure 29: RS-232 interface connector
RS-232 connector pinout
Pin number
Description
1 Not
used
2
TXD, transmit data
3
RXD, receive data
4 Not
used
5
GND, signal ground
6 Not
used
7
RTS, ready to send
8
CTS, clear to send
9 Not
used
The following table provides pinout identification for the 9-pin (DB-9) or 25-pin (DB-25) serial port
connector on the computer.
Computer serial port pinout
Signal*
DB-9 pin number
DB-25 pin number
DCD, data carrier detect
1
8
RXD, receive data
2
3
TXD, transmit data
3
2
DTR, data terminal ready
4
20
GND, signal ground
5
7
DSR, data set ready
6
6
RTS, request to send
7
4
CTS, clear to send
8
5
RI, ring indicator
9
22
* The Model 2657A does not use all RS-232 signals. See the topic
9 8 7 6
5 4 3 2 1
Rear Panel Connector
RS-232
Содержание 2657A
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