The following methods can be used to change the control of the on-going FB.
• Retrigger (Inputting Execute again)
• Continuous update (ContinuousUpdate)
With a retrigger/continuous update of the FB, input variables can be imported again to the FB instance in execution without
The fetch cycle of each input variable depends on the longest cycle in the following lists.
• Execution cycle of POU (abbreviation for Program Organization Unit) that calls the FB
• Buffer memory refresh cycle (Only when using the FB in the CPU module side)
• Operation cycle
To change input variables when Execute turns FALSE→TRUE and when ContinuousUpdate turns TRUE, be sure to secure
time longer than the cycle.
Also, when a retrigger/continuous update is performed to an instruction being buffered by multiple start of the motion control
FB, the change will be reflected at the FB switching.
• A retrigger/continuous update which is immediately after execution and immediately before termination of
the FB may be ignored.
• Even if a retrigger/continuous update is performed to an instruction being buffered, it may affect on the
control in operation.
In an FB whose start condition is Execute, a retrigger can be executed by the re-rising edge of Execute.
For input variables that can be changed by a retrigger, refer to each FB specification.
If ContinuousUpdate is TRUE when Execute turns FALSE→TRUE, input variables will be continuously imported.
For input variables that can be imported, refer to each FB specification.
4 START AND STOP
4.2 Retrigger/Continuous Update