HP 54501A - Tree Traversal Rules; Examples

Tree Traversal
Rules
Command
headers
are
created
by
traversing
down
the
command
tree.
A
legal
command
header
from
the
command tree
in
figure
4-1 would
be
":CHANNEL1:RANGE".
This
is
referred
to as
a
compound header.
A
compound
header
is
a
header
made
of
two
or more
mnemonics separated
by
colons.
The
mnemonic
created
contains
no spaces.
The
following
rules
apply
to
traversing
the
tree:
•
A
leading
colon
or
a
<
program
message
terminator
> (either
a
<
NL
>
or
EOI
true
on
the
last
byte)
places
the
parser
at
the
root
of
the
command
tree.
A
leading
colon
is
a
colon
that
is
the
first
character
of
a
program
header.
• Executing
a subsystem
command
places
you
in
that
subsystem
(until
a
leading
colon
or
a
<
program
message
terminator
> is
found).
In
the
Command
Tree,
figure
4-1,
use
the
last
mnemonic
in
the
compound
header
as
a
reference
point
(for
example,
RANGE).
Then
find the
last
colon
above
that
mnemonic
(CHANNELl:),
and
that
is
where
the
parser
will
be.
Any command
below
that
point
can
be
sent
within the
current
program
message
without
sending
the
mnemonic(s)
which
appear
above
them (OFFSET).
Examples
The OUTPUT
statements
are
written
using
HP BASIC
4.0
on
a
HP
9000
Series
200/300
Controller.
The
quoted
string
is
placed
on
the
bus,
followed
by
a
carriage
return
and
linefeed (CRLF).
Example
1:
OUTPUT 707;":CHANNEL1:RANGE
0.5
;OFFSET
0"
Comments:
The
colon
between CHANNELl
and
RANGE
is
necessary,
CHANNEL1:RANGE
is
a compound
command.
The
semicolon between
the
RANGE
command
and
the
OFFSET
command
is
the
required
<
program
message
unit
separator
>.
The OFFSET
command
does
not
need
CHANNELl
preceding it,
since
the CHANNEL1:RANGE
command
set
the
parser to
the
CHANNELl node
in
the
tree.
HP
54501A
Programming
Programming
and
Documentation
Conventions
4-5