3
r
SERIAL INTERFACE
The serial interface
is suitable
for
use with
printers, display units and keyboards
1
compatible with
RS232 and
RS423.
:
- -
'
3.1
DATA HANDSHAKE
The instrument
supports XON/XOFF
data handshake.
The
ASCII commands XON
(transmit on) and
XOFF (transmit
off)
are recognised when
outputting data to an
external device.
These commands
are
equivalent
to the ASCII device control
characters DCl
and DC3.
The instrument also asserts XOFF when it is
busy, and XON when it is free. Full
information is given in the standards:
*
American National
Standard Code
for
Information Interchange (ASCII)
X3.4 1977
*
BS
4730;
The United Kingdom
7-bit data code (ISO-7-UK) February
1974,
Section 5.3
*
CCITT Volume VIII.
1 Recommendation V3 "International Alphabet
No.
5”.
3.2
ECHO
The instrument echoes
all characters received
by
the serial
interface, unless the echo
function is disabled.
(See Chapter
5,
Section
8.3.)
3.3
INPUT COMMAND
TERMINATOR
AND
CHARACTER
FRAME
Valid command
terminators for
the serial interface are carriage return,
line
feed
,
or
semi-colon.
The character frame always
contains
one
start bit,
eight data bits, one
stop
bit
and no
parity.
3.4
SERIAL INTERFACE
CONNECTOR
Connection
to RS 423 devices
is made via the 25-way
sub-miniature D-type connector
on the serial
interface.
See Fig. 7.5. The pin functions
are shown in the connector
detail.
3.5
BAUD RATE
SWITCHES
The Baud rate
of the serial interface
is set by miniature toggle switches
on the rear
panel of the instrument.
This function
is described below.
The remaining interface
'
functions are
set from the [RS 423
CONFIGURE] menu
(Chapter
5,
Section
8.3).
Set the
RS
423
baud rate
to
the
required value (from 110
to
9600) by
means
of
the
8-way
BAUD
RATE switch (Fig.
7.5).
Only one of the eight
switches
should be set in the
down position, under
the
required
baud
rate.
JWS/1260/2
7.11
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