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67
Each
PMU
within the
message
is
made
up
of
a
PMU
Header
(a
mnemonic
of
ASCII
characters),
a
Header
separator
(a
white space
character),
Data and Data
separators
(,).
A PMU
is
constructed as
follows:
HEADER
[
]
DATA
,
DATA
,
DATA
,
DATA
,
DATA
;
NOTE:
In
this
example
the
white
space character
is
represented
by
square brackets
[
].
Text
spaces
shown
in the
preceding
and
following
examples
are included
for clarity only,
no
spaces in
messages
are
to
be used
except
where
indicated
by
the
square
brackets.
This device
accepts
Program
Messages
into
a
buffer that
can hold 10
string
characters
or
20 numerical
characters.
Response Messages
68
Response messages
are constructed
in
a similar
manner
to
program
messages.
Response
messages
consist of
Response Message
Units
(RMUs),
RMU
Separators
(;)
and
a
Response
Message Terminator (RMT).
The
RMT
is
always
the
NL
(orLF)
character
with
END.
A
response
message
is
constructed as
follows:
RMU
;
RMU
;
RMU
;
RMU
;
RMU RMT
69
This device
can
store,
in
the
Output
Queue,
five
Response Message
Units.
71
Each
RMU
within the
message
is
made
up
of
a
RMU
Header
(a
mnemonic
of
ASCII
characters),
a
Header
separator
(a
white space
character),
Response Data and Response
Data
separators
(,).
A
RMU
is
constructed
as
follows:
HEADER
[
]
RESPONSE DATA
,
RESPONSE
DATA
,
RESPONSE DATA
;
NOTE:
In this
example
the
white
space character
is
represented
by
square brackets
f
].
White Space Character
71
The
white space character
may
be any
ASCII
encoded
byte
in
the
ranges
of
0
to
9
and
11
to
32
inclusive.
The most commonly
used white
space character
is
the space character
(ASCII encoded byte
32)
as
generated by
a
QWERTY
keyboard
space
bar.
OVERLAPPED/SEQUENTIAL
COMMANDS
72
Every
device-dependent
command
is
defined as either sequential
or
overlapped.
73
A
sequential
command
is
started
and
completed
before the
succeeding
command
is
executed.
74
An
overlapped
command
is
started
but not
necessarily
completed
before the
succeeding
command
is
started.
75
The
synchronization
commands [*WAI
(Ref.
A6),
*OPC
(Ref.
A4),
*OPC?
(Ref.
A5)]
can be
used
to
either control or indicate
when
the
commands
have been
completed.
2151
OPS
A
15
7
1/DA
4-23
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