5 Programming HIMax System
HI 801 001 E Rev. 4.01 Page 76 of 122
During a reload, the global and local variables are assigned the values of the corresponding
variables from the previous project version. Names of local variables contain the POU
instance names.
This procedure has the following consequences, if names are changed and loaded into the
PES by performing a reload:
Renaming a variable has the same effect as deleting the variable and creating a new
one, i.e., it results in an initialization process. This is also the case for retain variables.
The variables lose their current value.
Renaming a function block instance results in initializing all variables, even retain
variables, and all function block instances.
Renaming a program results in initializing all contained variables and function block
instances.
This behavior may have unintended effects on one or multiple user programs and
therefore on the plant to be controlled!
The following factors limit the possibility to load a modified program into the controller by
performing a reload:
The changes described in Chapter "
Conditions for Using the Reload Function".
Time required to perform a reload.
The cycle takes longer due to the time required by the additional reload tasks. To prevent
that the watchdog triggers and the controller enters the error stop state, both SILworX and
the controller verify the additional time required to perform a reload. If the time required is
too long, a reload is rejected.
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Plan sufficient time reserve for the watchdog time and the target cycle time to be able to
perform the reload.
HIMA recommends the procedure in safety manual (HI 801 003 E) to evaluate the
watchdog time.
The watchdog and target cycle times can be increased for the duration of the reload, refer
to the SILworX online help for more details. This can be necessary if the defined time
reserve is too short and the reload procedure blocks in the Cleanup phase.
The online function only allows one the increase the watchdog and target cycle times, and
not to reduce them to the value set in the project.
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Take the following point into account when reloading step chains:
The reload information for step sequences does not take the current sequence status into
account. The step sequence can be accordingly changed and set to an undefined state by
performing a reload.
The user is responsible for this action.
Examples:
Deleting the active step. As a result, no step of the step chain has the active state.
Renaming the initial step while another step is active.
As a result, a step chain has two active steps!
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