IoDrvEtherCAT.FrameAtTaskStart (PROP)

PROPERTY FrameAtTaskStart : BOOL

TRUE: The frame for the slave is transferred at the beginning of the task (before the IEC task), which ensures minimum jitter. This command is used to achieve jerk-free movements of servo drives. If this flag is set to TRUE, the frame of the output buffer is written in the next cycle (see diagram below).

Default: FALSE (TRUE when using CODESYS SoftMotion)

Timing with FrameAtTaskStart set to false:

../_images/Buszyklus.png

Timing with FrameAtTaskStart set to true:

../_images/FrameAtTaskStart.png

(1) Read inputs from input buffer

(2) IEC task

(3) Writing outputs to output buffer

(4) Bus cycle

(5) Input buffer

(6) Output buffer

(7) Copy data to/from bus

(9) Bus cycle task, priority 1, 1 ms

(10) Cyclic task, priority 5

(11) Cyclic task, priority 10, interrupted by task 5