'Tasks and Events' Editor (Safety PLC)
The following information refers to a specific, typical device type. Your screen may differ.
This help topic describes the 'Tasks and Events' editor of the 'Safety PLC' PLANT node.
| Note
To be able to edit safety-related data, you have to be logged on to the Safety-related Area. Refer to the topic "Safety-Related Area with Password Protection" for details. |
In contrast to the standard controller, the Safety PLC executes exactly one task in which exactly one program is instantiated which is always the safety-related program named S_Main. Both the safety-related task and the program instance are created automatically on insertion of a controller with a Safety PLC in the PLANT. The program instance can neither be deleted nor edited and only the task properties 'Interval (ms)' and 'Watchdog (ms)' can be modified.
| Further Info
Further details and information can be found in the topic "Safety PLC Runtime Configuration". |
This topic contains the following sections:
Toolbar of the editor
| Toolbar button | Description |
|---|---|
 | The icon is inactive as only one task is allowed and cannot be moved. |
 | The icon is inactive as only one task is allowed and cannot be moved. |
 | Opens the toolbar for local find and replace operations. |
Description of the task editor table
The 'Tasks and Events' editor contains a hierarchically structured table where tasks and events can be specified and program instances can be assigned.
Entries in the table can be expanded and collapsed by clicking the appropriate icons 
and 
| Column | Description | |
|---|---|---|
| Name | Name of the table entry. Depending on the hierarchical position, this can be:
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| Task type | The task type specifies the condition which starts the execution of the task.For the Safety PLC only the type 'cyclic' is allowed and can not be edited. | |
| Event name | Event that triggers the execution of the task. This is not allowed and therefore not editable for the Safety PLC. | |
| Program type | Program that is assigned to the task (type of the instance).The Safety PLC executes exactly one program which is always the safety-related program named S_Main. This program instance is created automatically on insertion of a controller with a Safety PLC in the PLANT. It can neither be edited nor deleted.Further safety-related programs can be created in the COMPONENTS area but they cannot be instantiated and are therefore not executed by the Safety PLC. | |
| Interval (ms) | Time interval in ms in which the cyclic SafetyTask is executed (integer or floating point value).The time value should be a multiple of the timer resolution of the Safety PLC.
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| Priority | Priority for calling the task. The SafetyTask has always the highest priority 0 which cannot be edited. | |
| Watchdog (ms) | Maximum time a task is allowed to run for one cycle (call). If the watchdog time exceeds, a watchdog error is generated. This way, the watchdog monitors the execution and completion of a task within the defined time. The watchdog is executed during each system cycle.The watchdog time normally should be shorter than the Safety PLC cycle time.Observe the hazard message below this table.The valid value range depends on the Safety PLC. Please refer to the PLCnext Info Center and the device manual for minimum and maximum watchdog settings.
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| Comment | User-defined comment. |
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WARNING
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Non-conformance to safety function requirements
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