116 Epsilon EP-P Drive Reference Manualï€
www.controltechniques.com Revision: A4
If the user wishes to operate two programs simultaneously, the two programs must be assigned to two different tasks. Multiple programs can
be assigned to the same task if desired, but that means that the two programs can not be run at the same time. If a given program calls another
program, then calling and the called programs must be on the same task. All programs default to task zero and therefore will not run
simultaneously unless specified to do so.
Timing Diagrams
In Figure 125 the update rate is set to 1600 microseconds (Found on the Setup View). The first routine to be processed in the update rate is
the control loop update. Next, all messages will be handled. If no message has been sent from a Modbus master and no faults are active, then
this step is skipped. After all messages are processed, then execution switches to the user programs. The user programs are assigned to
tasks, and the tasks are handled in ascending order starting with task 0. If a task has been assigned, but not initiated, then that task can be
skipped. After 1600 microseconds has passed, the task is stopped, and the process is repeated using the next available task. Once each task
has been processed (depends on how many have been assigned by the user), the whole process starts over at the first task. This process is
accurate as long as no program is blocked. The following figure shows examples of user programs and task numbers and how the drive
processes them.
Figure 126: Diagram of User Programs with Multiple Tasks
T0
T0 T0 T0 T0
Control Loop
User Program
T0
Update Rate
Control Loop + User Program on one Task
T0
T1 T0 T1 T0
Control Loop
User Program
T1
Update Rate
Control Loop + User Programs on two Tasks
T0
T1 T2 T0 T1
Control Loop
User Program
T2
Update Rate
Control Loop + User Programs on three Tasks
T0
T0
T0 T1 T1
Control Loop
User Program
T0
Update Rate
Control Loop + User Programs on two large Tasks
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