REMOTE PROGRAMMING
4-1
INTRODUCTION
The SR715 / SR720 LCR meters may be remotely
programmed via either the RS232 or GPIB (IEEE-
488) interfaces. Any computer supporting either of
these interfaces may be used with the SR715/720.
Both interfaces are simultaneously active. The
SR715/720 will respond to commands from either
interface and return answers to the interface from
which the command came. All front and rear panel
features (except power) may be controlled.
COMMUNICATING WITH GPIB
The SR715/720 supports the IEEE-488.1 (1978)
interface standard. It also supports the required
common commands of the IEEE-488.2 (1987)
standard. Before attempting to communicate with
the SR715/720 over the GPIB interface, the
SR715/720's device address must be set. The
address is set by the rear panel switches SW2.
The address may be set between 0 and 30 by
setting the binary value of the address on switches
A0 to A4. Each switch may have the value 0
(down) or 1 (up). The address is set by the
formula: Address = A0 + 2
*
A1 + 4
*
A2 + 8
*
A3 +
16
*
A4.
COMMUNICATING WITH RS232
The SR715/720 is configured as a DCE (transmit
on pin 3, receive on pin 2) and supports CTS/DTR
hardware handshaking. The CTS signal (pin 5) is
an output indicating that the SR715/720 is ready,
while the DTR signal (pin 20) is an input that is
used to control the SR715/720's transmitting. If
desired, the handshake pins may be ignored and a
simple 3 wire interface (pins 2,3 and 7) may be
used. Before communicating with the SR715/720
the RS232 characteristics must be set. The RS232
interface is configured using the rear panel
switches SW1. The first three switches set the
baud rate to 300, 600, 1200, 2400, 4800, or 9600
baud. Parity may be enabled or disabled, and set
to even or odd. And, the number of bits in a data
byte may be set to 7 or 8.
Sw1 Settings For Rs232 Parameters
bit0
bit1
bit2
Baud Rate
0
0
0
300
1
0
0
600
0
1
0
1200
1
1
0
2400
0
0
1
4800
1
0
1
9600
0
1
1
19.2 k
bit3
1
parity on
0
parity off
bit4
1
even parity
0
odd parity
bit5
1
8 data bits
0
7 data bits
Note:
the SR715/720 must be set to 8 data bits if
the binary data output formats are to be used.
FRONT PANEL LEDS
To assist in programming, the SR715/720 has 3
front panel status LEDs. The ACT LED flashes
whenever a character is received or sent over
either interface. The ERR LED flashes when an
error has been detected, such as an illegal
command, or parameter out of range. The REM
LED is lit whenever the SR715/720 is in a remote
state (front panel locked out).
COMMAND SYNTAX
Communications with the SR715/720 use ASCII
characters. Commands may be in either UPPER
or lower case and may contain any number of
embedded space characters. A command to the
SR715/720 consists of a four character command
mnemonic, arguments if necessary, and a
command terminator. The terminator may be
either a carriage return <cr> or linefeed <lf> on
RS232, or a linefeed <lf> or EOI on GPIB. No
command processing occurs until a command
terminator is received. All commands function
identically on GPIB and RS232. Command
mnemonics beginning with an asterisk "
*
" are
IEEE-488.2 (1987) defined common commands.
These commands also function identically on
RS232. Commands may require one or more
parameters. Multiple parameters are separated by
commas ",".
Multiple commands may be sent on one command
line by separating them by semicolons ";". The
difference between sending several commands on
the same line and sending several independent
commands is that when a command line is parsed
and executed the entire line is executed before any
other device action proceeds.
There is no need to wait between commands. The
SR715/720 has a 256 character input buffer and
processes commands in the order received. If the
buffer fills up the SR715/720 will hold off
handshaking on the GPIB and attempt to hold off
handshaking on RS232. If the buffer overflows the
buffer will be cleared and an error reported.
Содержание SR715
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