Emerson Epsilon EP Drive 400518-01 Manual de instalación descargar pdf (Pagina 129)

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Programming

Program Multi-Tasking

Many applications require the operation of a background task that operates outside of the main program loop, but must be

consistently processed. For instance, a background task that performs calculations for values sent to an operator interface or

a background task that monitors parameters for fault detection.

The FM-4 and Epsilon EP-P processor has the ability to execute multiple tasks. Because only one task can be processed at a

time, a process called time slicing must be used. Time Slicing is simply splitting the total processing time between multiple

tasks. The processor stops all tasks and updates the control loop every 800 microseconds (default, update time may be set by

user). Inside the control loop update, the device updates the motion trajectory, captured data, digital inputs and outputs, and

other control parameters. Between each control loop update, the device processes messages (i.e. Modbus, Keypad, LCD,

Faults, etc.) and then runs as much of the user programs as possible until the next control loop update begins. Each update, a

different task is processed, and therefore how long it takes a given user program to complete depends how many tasks have

been created.

The task assignment is done on the program view. The diagram below shows the program view with the Task Number

parameter. Use the up and down arrows next to the Task Number to change the value. To create a new Task, simply click on

the up arrow until PowerTools Pro asks if you wish to create a new Task.

Figure 93: Program View with Task Number Detail

The FM-4 module and Epsilon drive allows up to four different tasks in a single application.

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.

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Emerson Epsilon EP Drive 400518-01 Manual de instalación Pagina 129