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M o d e l DRC-93C
Section
IV
DRC-93C
from interrupting the
B U S
that only new s t a t u s reports w i l l
CONTROLLER.
However, the
BUS CON-
be
registered
by
the
DRC-93C.
TROLLER
can still read the Status
Executing the
Q
command (Section
R e g i s t e r t o determine appropriate
4.11.3)
a l s o
resets
the
Status
instrument conditions.
Register t o a l l zeros.
Reading the
Status Register resets a l l of i t s
4.11.1
The
Service
Request
b i t s
t o zero.
T h e
Service
Request
Message
is
4.11.2.1
Status
Reports 0 and 1
-
independent of a l l other
IEEE-488
Display
and Control
Data Ready.
a c t i v i t y and is s e n t on a s i n g l e
B i t 0
of the Status Register is set
l i n e called the
SRQ
l i n e .
When the
when a v a l i d Display data reading
Service Request is sent and more
is available.
B i t 1
of the Status
than one instrument on
t h e
Bus has
Register is set when a v a l i d Control
the c a p a b i l i t y t o send thismessage,
data reading is available.
I f the
the
BUS
CONTROLLER
must
decide
Service Request is enabled, either
which
instrument
is sending the
one of these being set w i l l cause
request.
T h i s
is done by conducting
the
DRC-93C
t o p u l l the
SRQ
manage-
a "Serial
Poll"
of the instruments
ment low t o signal t h e
BUS CON-
on
t h e
Bus.
The
instrument polled
TROLLER.
These
b i t ( s )
are reset t o
responds by sending a Status Regis-
zero upon reading the Status Register
ter.
The
Status R e g i s t e r indicates
on response t o a serial p o l l o r
i f
whether
the
device
has
requested
the
reading is no longer valid.
service and
i f
so, f o r w h a t reason.
These
functions can
be
inhibited by
Once
t h e
reading on a given channel
turning their corresponding
b i t s
i n
becomes stable (or v a l i d ) , a service
the Status Register mask o f f .
request is issued by the
DRC-93C
provided that
B i t 6
i n the Status
4.11.2.2
Status
Report
2
-
T h e
Register
Mask
is set (See
4.11.2.5)
.
Control
Channel L i m i t .
When the
W i t h
the
SRQ
b i t
of
the Status
control sensor reading gets w i t h i n
Register
m a s k
disabled,
no
SRQ
the chosen
l i m i t from
t h e
set point,
i n t e r r u p t by t h e
DRC-93C
w i l l
be
b i t
2
is set i n
the Status Register.
generated,
however,
the
BUS CON-
I f
the Service Request
is enabled
TROLLER
can still read
t h e
Status
this
b i t
being set w i l l cause the
Register t o determine appropriate
DRC-93C
t o p u l l
the
SRQ
management
instrument conditions.
low t o signal the
BUS
CONTROLLER.
As w i t h a l l of the Status Reports,
4.11.2
The
Status
Register
and
this b i t
is reset t o zero upon
S t a t u s
R e p o r t s
reading
t h e
Status Register.
T h e
b i t
w i l l
not r e v e r t t o zero
i f
the
T h e
DRC-93C
Status Register is a
control sensor difference from the
s i n g l e byte of data from the
DRC-93C
set point l a t e r exceeds the l i m i t
containing
f i v e
b i t s
called the
selected.
Status Reportswhich give information
indicating which process is complete,
The
control channel l i m i t is entered
whether the channel w a s changed, o r
using the
Q
command.
(See
Section
a l i m i t , overload or error encounter-
4.11.3.2).
ed
.
This
function can
be
inhibited by
The Status Register can
be
read a t
turning off b i t
2
i n the Status
any t i m e by means of a Serial
P o l l
Register mask.
Enable
command.
Reading
the
Status Register resets
4.11.2.3
Status
Report 3
-
Display
the Status
R e g i s t e r t o a l l zeros
so
B i t 3
of the
Sensor Channel
Change.
COPYRIGHT
3/88 LSCI
4-19
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