Tektronix 2221 - GPIB Parameter Selection; PRIMARY ADDRESS and Status Indicators

Options and
Accessories -
2221
Operators
П
П
П
GPIB
Parameter
Selection
•
LISTEN
ONLY
mode
permits the
instrument to
receive data over the GPIB .
C
The
correct
selection
of
GPIB
parameters (
primary
address
,
message terminator , and talk
/ listen mode )
must
be made
before
power
on .
That is
when the
GPIB
PARAMETERS
Switch
is
read to
determine what the
address and
other settings of
the
switch are .
See
Table 7-6 (
shown
previously ) to
determine the
specific
parameters switch
settings
.
• TALK / LISTEN mode ( both TON and LON modes
unselected ) allows the instrument to both send and
receive data over the GPIB .
OFF
BUS mode (
both
TON
and
LON
modes
selected
)
switches the
instrument off
the bus
(
same as
setting
address to
31 ) .
П
1
PRIMARY
ADDRESS .
The
selected
GPIB
address
establishes
the
talk
and
listen
address for
the
oscilloscope .
It can be set
to any value
between and 31 ,
inclusive
.
Address 31
is "
OFF LINE . "
With
an
address of
31 , the
instrument still
presents an
active
load
, but it
neither
responds to nor interferes with any bus traffic .
To select
a
different Talk /
Listen mode ,
see the GPIB
PARAMETERS
switch
settings in Table 7-7
. The new
set
tings must be made before power on to be in effect .
Option 10 interface Status Indicators
SECONDARY
ADDRESS
-
Not
implemented in
the
2200
Family of
digital
storage
oscilloscopes
.
INPUT
END
- OF -
MESSAGE
TERMINATOR — The
end
of - message terminator can be selected to be either
the End - or -
Identify
( EOI )
interface signal or the
Line - Feed
( LF )
character
.
Three
indicators appear in
the CRT
readout
to
indicate
the
status
of
the
GPIB
communication
option
.
The
indicators
are
labeled
SRQ (
service
request
pending )
,
ADDR (
addressed
to
talk ) , and
PLOT ( output
data to the
plotter ) on the
CRT bezel .
The active
indication
is seen
as
an
intensified line in
the CRT
display
just
below
the
associ
ated label .
Refer to
Figure
7-2
for the
location
of
the
communications
interface status
indicators
.
When EOI (
normal
mode ) is
selected as
the
terminator ,
the instrument will :
•
accept only
EOI as
the end - of
-
message
terminator ,
and Tektronix
DIGITAL
STORAGE
OSCILLOSCOPE
$ ng
4DOR PLOT
•
assert EOI
concurrently with
the last
byte of
a message .
selected as
the
When
LF is
instrument
will :
terminator ,
the
Л
П
n
1
7
1
П
П
Л
П
П
П
accept
either
LF
or EOI
as the end
- of -
message
termi
nator
,
and
send Carriage Return ( CR ) followed by LF at the end
of every
message
, with EOI
asserted
concurrently
with the LF .
MODE - Four
talk / listen
modes
TALK / LISTEN
are
selectable
:
PLOT
SRQ
(
SERVICE
REQUEST )
ADDR
( TALK OR
LISTEN )
6530-27
•
TALK
ONLY
mode
allows the
instrument to
send
data over
the GPIB .
Figure 7-2 . SAQ , ADDR , and PLOT indicators .
C
7-7