Rockwell Automation 57C400-1 115V AC/DC Input Module - Manual (Page 16)

4Ć2
The frequency with which tasks read their inputs and write their
outputs depends on the language being used. Ladder logic and
control block tasks read inputs once at the beginning of each scan
and write outputs once at the end of scan. BASIC tasks read an input
and write an output for each reference throughout the scan.
4.3.1 Ladder Logic Task Example
STARTPB LIGHT
1050
run
run
The symbolic names LIGHT and STARTPB reference the input
modules that were defined in the configuration. The trailing at symbol
@" is not used in ladder logic tasks. The symbolic name run" is
local to the ladder logic task and does not have I/O associated with it.
4.3.2 BASIC Task Example
1000 COMMON LIGHT@ \!Fault light
1010 COMMON STARTPB@ \!Start PushĆbutton
2000 LOCAL RUN@ \!Line run
3000 !
4000 !
5000 RUN@ = NOT LIGHT@ AND ( STARTPB@ OR RUN@)
5500 !
6000 END
The symbolic names LIGHT@ and STARTPB@ reference the input
modules that were defined in the configuration. The symbolic name
RUN@ is local to the BASIC task and does not have I/O associated
with it.
4.3.3 Control Block Task Example
2400 COMMON STARTPB@ \!Start pushĆbutton
2500 LOCAL MOMENTARY@ \!Momentary output
3000 !
5000 CALL TRANSITION( INPUT=STARTPB@,
OUTPUT=MOMENTARY@)
5500 !
6000 END
The symbolic name STARTPB@ references the input module that
was defined in the configuration. The symbolic name
MOMENTARY@ is local to the control block task and does not have
I/O associated with it.