Fluke 8506A Instruction Manual page 242

S505A/8506A-G6
at least
one
of the features
from
each of the following
characteristics.
1.
Timing Format
-
Synchronous
or
Asynchronous.
2.
Transmission
Mode
- Simplex, half-duplex, or
full
duplex.
3.
Baud
Rate
(bits
per second) -50,
75, 110, 134.5,
150,
200, 300, 600, 1200, 1800, 2400, 4800, 9600.
4.
Bits per character
-
5, 6, 7, 8.
5.
Parity Bit
-
Odd,
even, high, low, not used.
6.
Data
Interface Levels
-
El
A
or 20
mA
current
loop.
606-9.
Timing
formats conforming
to
both
synchronous
and asynchronous
operation are
shown
in
Figure
617-1.
In asynchronous
operation each character
is
bracketed
by both
start
and
stop
bits.
These
bits
separate the characters
and
synchronize both the
transmission
and
receipt
of
data.
When
data
is
not being
sent the
data
line
is
held high. In
synchronous
operation a
sync character
is
sent prior to each data stream
(a
data
stream usually consists of a block of
characters).
When
the line
is
idle, a
fill
or sync character
is
continuously
transmitted.
606-10. Transmission
mode
is
an
overall
system
requirement.
It
defines the
communication
ability
of
both
instruments
in
the
system
configuration.
Simplex
indicates
data transmission
in
one
direction only.
Half-
duplex permits two way communication,
but not
simultaneously. Simultaneous transmission of data
in
both
directions defines the
full
duplex
system.
Obviously,
an instrument capable
of
full
duplex operation can be
downgraded
to
simplex
operation.
However,
the reverse
is
not possible without degrading
the.
system
capability.
606-11.
Baud
rate
is
usually selectable
on
the
RS-232-C
Interface. If
it is
not, the
manufacturer
usually
offers
a
choice
when
the
instrument
is
purchased.
606-12. Character format
(bits
per character
and
parity)
is
somewhat
flexible
between
instruments. Investigate the
requirement
of
both instruments
before
committing
either to a
system
configuration.
606-13.
Data
interface levels
can occur
as either
El
A
voltage
levels
or
as
a 20
mA
current loop. At
times
an
interface offers
both
simultaneously.
The
20
mA
current
loop
is
used almost
exclusively for teletypewriter, or
paper tape punch/
reader interface.
EIA
voltage
levels
are:
1
or
OFF —
-
15
to
-3V
dc,
0 or
ON =
+3
to
+
I5V
dc.
@06-14.
OPERATING FEATURES
606-15. Attached
to the
PCB
and
accessible
through a
port on
the rear
panel (Figure 606-1)
are a standard
specified
connector
and
a
switch module
with
eight
micro-switches.
The
connector
is
standard for the
RS-232
Interface
and
is
specified
by
the
standard document.
The
eight switches
control the
operating
modes
of the
interface
and
the
BAUD
rate.
The modes
selected
by
the
switches are
shown
in
Table 606-1 and Table
606-2.
The
selection of
Odd
or
Even
parity
with switch
8
is
applicable
only
if
the parity feature has been
selected
using
the
jumpers
described below.
606-16.
The
interface
is
shipped configured
for
an
eight
bit
character without
parity.
Selection of parity
and
five,
six
or seven
bit
characters
can be accomplished by
installing
jumpers
into the
PCB
as
shown
in
Table 606-3.
606-2