System Manual Modular Systems
6 User Program
HI 800 191 E Rev. 2.02
Page 41 of 114
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In the examples illustrating the multitasking modes, input and output processing are
represented as empty spaces at the beginning and the end of each CPU cycle.
6.3
Reload - with CPU 03
If user programs were modified, the changes can be transferred to the PES during operation.
The operating system checks and activates the modified user program which then assumes the
control task.
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Take the following points 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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Take the following points into account when reloading actions:
During the reload, actions are loaded with their corresponding data. All potential consequences
must be carefully analyzed prior to performing a reload.
Examples:
If a timer action qualifier is deleted due to the reload, the timer expires immediately.
Depending on the remaining settings, the
Q
outputs can therefore be set to TRUE.
If the status action qualifier (e.g., the
S
action qualifier) is deleted for a set element, the
element remains set.
Deleting a
P0
action qualifier set to TRUE actuates the trigger function.
Prior to performing a reload, the operating system checks if the required additional tasks would
increase the cycle time of the current user programs to such an extent that the defined
watchdog time is exceeded. In this case, the reload process is aborted with an error message
and the controller continues operation with the previous project configuration.
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The controller can interrupt a running reload process.
A successful reload is ensured by planning a sufficient reserve for the reload when determining
the watchdog time or temporarily increasing the controller watchdog time by a reserve.
Any temporary increases in the watchdog time must be agreed upon with the responsible test
authority.
Also exceeding the target cycle time can result in a reload interruption.
The reload can only be performed if the
Reload Allowed
system parameter is set to ON and the
Reload Deactivation
system variable is set to OFF.
