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Section
III
outputted
in the
following
format:
(Example
listing:
NDCfXXXXXXE-Y).
Status
Code Alpha*
N Normal
Operation
OL Overload
R
Ratio Mode
S Sample/Hold Mode
RS
Ratio
and Sample/Hold Mode
Function
Code*
AC
AC Volts
DC DC Volts
KO Kilohms
T Test
*Status
and Function
are two-character codes. lf
only one
character is required,
a
blank space will
be
left
so
that
the total
output
format
will always
be the same
length.
Polarity
+
Positive
Input
or Positive
Ratio
-
Negative
Input
or Negative
Ratio
Model
3490A
3-127.
Service
Request.
The
3490A
is
capable
of re-
questing
service on the
bus
and responding
to
serial
polling
for identification
and
status.
If
either
mode of
operation
which
specifies interrupt with output
(M5
or
M7)
is
programmed
and
34904 is
not programmed
to
talk,
it will
pull
the
Service
Request
(LSRQ)
line
LOW
after each
reading.
3-128.
For serial
polling, the controller must
pull
the
Multiple
Response
Enable
(MRE)
line LOW and send
both the
Status
Poll
Enable
(SPE)
command and the
3490A
talk address.
The
SPE
command is octal code
030,
binary code
00
011 000.
If the 3490A has
pulled
SRQ LOW, when
it
receives SPE
and its
talk
address
it
will transmit the ASCII character
xlxxxxxx. The sev-
enth bit
being a
"l "
signifies that the 3490A did request
service. The
other
bits do not convey any
information
concerning the status. After
it
receives
the
Status
Poll
Dsable
(SPD)
command
(octal
code
031, binary code
00
0ll
001),
the 3490A will output
the reading
data,
since
it is still
addressed
to talk. After outputting
the
data,
it
will
return
the
Service
Request line
to
HIGH.
If
it is
unaddressed to talk before
the
SPD
command is sent, it
will keep the
SRQ
line LOW and
wait
for
its
talk addres
to output or its listen address
to
be
reprogrammed. It
will set SRQ
HIGH
if it is reprogrammed.
3-129. lf the 34904
is in operating mode
M5 or
M7
and
receives
the
SPE
command and
its talk
address before a
reading is completed,
it will
respond with
the
character
x0xxxxxx. The
seventh bit being a
"0"
indicates that it
did not request
service,
and
the other bits
have
no
significance conceming status. This code
(seventh
bit
"0")
is
also
transmitted if the
3490A is
in any of
the
other
modes
of operation
(M0,
Ut, M2,M3, M4, or M6)
and
it
receives
the
SPE
command and
its talk
address.
Data
xX)c()ü
E
Y
CR
LF
J-t -
Six digits,
most significant
digit first
Exponent
Identifier
Polarity
of Exponent
Exponent (Range
Digit)
Carriage
Return
Line Feed
MRE
Data Lines
LDAV
HRFD
Printer and 3490A
will accept
data
390A and
printer
will not
accept data
349OA
and
printer
will
accept
data
34904
and
printer
finished
processing
data
3490A
and
printer
will
not
accept data
Printer
will not
accept data
Printer
and
34904
processing
data
34904
and
printer
processing
data
Printer
and
34904
finished
processing
data
Figure 3-9. Timing
Diagram,3490A
Addressed to
Talk.