User manual

Publication LOGIX-AP010B-EN-P - May 2010 33
Software Conversions - Program Structure Chapter 2
Periodic Task
Step 5 and RSLogix 5000 software allow tasks to be programmed that will
execute at defined intervals. In the S5 PLC, the number of tasks and the
permitted time intervals is dependent on the model of controller used. For
example, in the S5-135U PLC Series, there are up to nine periodic tasks that
can be executed. These programs reside in Organization Blocks OB10 to
OB18 with each OB being executed, predefined-time intervals from 10 msec
to 5 sec.
In RSLogix 5000 software, the equivalent to the S5 Periodic Task is indicated
in an RSLogix 5000 project as follows:
By right-clicking on this icon and choosing Properties, the following
configuration menu for the periodic task is displayed. From this menu, the
executed task can be configured including task priority where tasks with lower
numbers indicate a higher priority.