Rockwell Automation 57C415 24V AC/DC Input Module - Manual (Page 16)

4Ć2
4.3.1 Ladder Logic Task Example
1050
LIGHT STARTPB run
run
The symbolic names LIGHT and STARTPB reference the input
modules. 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. 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. The
symbolic name MOMENTARY@ is local to the control block task and
does not have I/O associated with it.
4.4 Restrictions
This section describes limitations and restrictions on the use of this
module.
The 24V AĆC/DĆC Input Module is a read only module. Attempts to
write to it will cause a bus error (severe system error). The following
are examples from programs that write to the module and should
therefore be avoided:
a. Referencing the module from a coil in a ladder logic task.
b. Referencing the module on the left side of an equal sign in a LET
statement in a control block or BASIC task.
c. Referencing the module as an output in a control block function.