Model 5340A
Installation and Remote Programming
READY
FOR
DATA
(RFD)
LOW
HIGH
One
or
more
All
5340A’s
5340A’s
not
are
ready
ready
for for
data
data
When the controller sets ATN low, all 5340As will set DAC to its valid state within 200
nsec. When the controller sets ATN high, the
5340A’s that have not been addressed to
listen will not drive DAC, those addressed to listen will set DAC to its valid state within
200 nsec.
DATA ACCEPTED
(DAC)
LOW
HIGH
One or
more
All
5340A‘S
5340As
has
have
not accepted accepted
the
data
the
data
The listener must not set DAC low until
it
senses DAV is high.
It
may do
so
before or
at
the same time that it sets RFD high. It must not return DAC high until
it
senses DAV
is
low and may do
so
after
or
at
the same time that
it
sets RFD low.
h. DATA VALID (DAV)
DAV
is
the handshake line that indicates the validity of information on the data lines. Its
relationship to the other handshake lines and ATN
is
shown in Figure 2
-
1 and Table 2
-
1.
It is driven by TALKERS: the controller when ATN
is
low and by the instrument
addressed
to
talk when ATN
is
high.
It
is
sensed by LISTENERS: all, 5340A’s if ATN
is low and by the instruments addressed to listen when ATN
is
high.
When DAV is low, the states of data lines
DIOl through D107
are
unconditionally valid
and may be accepted by all listeners
at
their own time. To allow for cable rise time,
ringing, etc., the
5340A, when addressed to TALK, does not set DAV low until 2 ysec
after
it
has placed valid data
at
its
output connector.
It
assumes that the controller has
taken similar precautions. DAV can only be driven low if RFD and
IFC
are high. When
DAV
is
high, the information on the data lines is not valid. DAV cannot be set high
unless DAC is high and RFD
is
low.
Table 2
-
1. Relation of ATN and the Handshake Lines (RFD, DAC, DAV)
STATE
OF
ATTENTION
LINE (ATN)
L
ADDRESS
0
MODE
W
n
DATA
I
MODE
G
H
(1)
Driven
by
all
5340As
(2)
Sensed
by
controller
(3)
5340A’s
drives
to
its
valid state
within
200
ns
of
ATN
going
low
have
accepted
for
data accepted
data
the
data
(1)
Driven
by
ALLNstruments addressed
to
LISTEN
(2)
Sensed
by
thp
instrument
addressed
to
TALK
(3)
All
instrqments not addressed
w
ill not drive
LOW
HIGH
Controller Controller’s
has
valid
data
not
data on
valid
lines
(1)
Driven
by
controller
(2)
Sensed
by
5340A’s
The
addressed
The
addressed
TALKER has TALKERS
valid
data data
not
on
lines
valid
(1)
Driven
by
the
instruments
(2)
Sensed
by
ALL instruments
addressed
to
TALK
addressed
to LISTEN
2
-
5
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