Circular Queue Mode; Loops - Scanlab RTC 5 PC Interface Board Installation And Operation Manual

6.5.4 Circular Queue Mode

®
The RTC 5 does not support the circular queue mode
that could be activated on the RTC
set_list_mode. But the RTC
emulate this operational mode via an alternating list
change and the command
load_list ( 3, 0 ) ensures that – as in the
® ®
RTC 3/RTC 4's circular queue mode – new
commands will be loaded only into an already
processed list (that isn't BUSY), without needing to
explicitly supply the number of the list. And
continuous processing of list commands is not
hindered by the simultaneous loading of new
commands (also see "Alternating List Changes", page
75 and "Loading with Protection", page
Users who only want to assign the list memory's full
capacity to a single list – as realized in the
® ®
RTC 3/RTC 4's circular queue mode – can accom-
plish this very simply via config_list (page

6.5.5 Loops

Although list jumps (see page
jumps (see page 213) let you repeat any number of
list commands limitlessly or under external control,
precisely specifying the number of executions isn't
always reliably possible. But this can be achieved with
the command pair list_repeat
command sequence between these two short list
commands will execute exactly as often as specified
with the list_until command's parameter, but at least
once. Here, nesting up to 8 loops deep is allowed.
The commands list_repeat
always be used in pairs. Unpaired or superfluous
commands (list_until without an associated
list_repeat, as well as list_repeat
to a nesting depth greater than 8) will be ignored.
Empty loops (e.g. list_repeat
list_until) will terminate immediately and not be
repeated.
You can place such command pairs not only within
lists, but also within subroutines.
In subroutines, list_until performs a
the address directly after the associated list_repeat.
Loops won't function beyond the bounds of a
subroutine, because list jumps into or out of subrou-
tines aren't permitted (see
®
RTC 5 PC Interface Board
Rev. 1.9 e
6 Developing User Applications
® ®
3/RTC 4 via
®
5 can effectively
load_list (page 336).
72).
243).
81) and conditional
and list_until. The
and list_until must
commands leading
directly followed by
list_jump_rel to
page 81).
Within lists, however, list_until
list_jump_pos (to the address directly after the asso-
ciated list_repeat). Here, list_repeat
can even reside in two different lists, provided that
list changing is ensured via either an explicit list jump
or an automatic list change. If, on the other hand, a
list actually terminates (e.g. when using
auto_change_pos), then the
get automatically deleted and the started loop can no
longer be ended because the next
has its associated list_repeat.
set_end_of_list will delete the entire loop
management if no automatic list change exists, but
list_return will not.
Explicit list jumps to a list_repeat/list_until
body or from inside a loop to a loop-external location
are permissible, but can't be monitored. Careless use
could therefore compromise loop management
integrity so severely that started loops won't execute
as expected (but subroutine calls from inside a loop
are always reliably possible as long as the subroutine
itself contains no unpaired
commands).
executes a
and list_until
list_repeat stack will
list_until no longer
loop's
list_repeat/list_until
82