Sean u y v vértices no adyacentes de G. El número mínimo de vértices de un conjunto u–v separador es igual al número máximo de caminos internamente disyuntos entre u

Requirements

You must have programmed your safety program.

Rules for F-Runtime Groups of the Safety Program

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• The channels of an F-I/O can be accessed from only one F-runtime group. • Variables of the F-I/O DB in an F-I/O can only be accessed from one F-runtime

group and only from the F-runtime group from which the channels of this F-I/O are accessed (if access is made).

• An F-program block must not be used in more than one F-runtime group. • F-FBs can be used in more than one F-runtime group but they must be called

with different instance DBs.

• Instance DBs can only be accessed from the F-runtime group in which the associated F-FB is called.

• Individual parameters of F-DBs (except the F-shared DB) may be used in only one F-runtime group (however, an F-DB can be used in more than one F- runtime group).

• The F-runtime group for which you furnished the DB can read and write to a DB for F-runtime group communication, while the "receiver" F-runtime group can only read this F-DB.

• F-blocks must not be called directly in an OB; rather, they must be inserted into one or two F-runtime groups.

• For optimal use of local data, you must call the F-CALL blocks (the F-runtime groups) directly in OBs (cyclic interrupt OBs, to the extent possible); you should not declare any additional local data in these cyclic interrupt OBs.

• Within a cyclic interrupt OB, the F-CALL (the F-runtime group) should be executed before the standard user program; that is, it should be at the very beginning of the OB, so that the F-runtime is always called in fixed time intervals, regardless of the length of execution of the standard user program. • An F-CALL can only be called once. Multiple calls are illegal and can cause the

F-CPU to go to STOP mode.

• The process image of inputs and outputs of standard I/O and memory bits can be accesses from several F-runtime groups.

Procedure for Defining an F-Runtime Group

1. In the SIMATIC Manager, select the Options > Edit Safety Program menu command. The "Safety Program" dialog box will appear. Activate the "Runtime Groups..." button to open the "Edit F-runtime groups" dialog box.

2. In the "Edit F-Runtime Groups" dialog, select "New...". The "Define New F-Runtime Group" dialog is displayed.

3. From the drop-down list, select the FC that you want to define as the F-CALL for the new F-runtime group or specify another FC. This FC is automatically created as soon as you exit the "Edit F-Runtime Groups" dialog with "OK." 4. Define the F-program block of the F-runtime group by selecting the F-FB/F-FC

from the drop-down list that you want to define as the F-PB for the new F- runtime group (symbolic entry possible). Only F-FBs/F-FCs without parameters can be defined. If the assigned block is an F-block of type "FB", you must specify an instance DB (e.g., "DB10") for "I-DB for F-program block" (symbolic entry possible). This I-DB is automatically created as soon as you exit the "Edit F-Runtime Groups" dialog with "OK." The number of the I-DB must not come from the range reserved in HW Config. If you specify an existing I-DB, it must match the selected F-program block.

5. The F-CPU monitors the F-cycle time in the F-runtime group. For "Max. Cycle Time of F-Runtime Group in ms", enter the maximum permissible time between two calls of this F-runtime group (maximum of 1,020,000 ms); see Safety Engineering in SIMATIC S7 system description.

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The F-runtime group call interval is monitored for maximum value, that is, to verify whether the call is executed often enough, but not whether it is executed too often. For this reason, fail-safe timers must be implemented by means of F-application blocks from the Distributed Safety F-library (V1) and not by means of counters (OB calls).

6. If this F-runtime group is to provide data to another F-runtime group, select an F-DB for "DB for F-runtime group communication" from the drop-down list or specify another F-DB (symbolic entry possible). This F-DB is automatically created as soon as you exit the "Edit F-Runtime Groups" dialog with "OK." 7. After the "OK" button is activated, the entries in the "Edit F-Runtime Groups"

dialog undergo an internal validity check and are then applied. This dialog also displays the symbolic names of the newly created F-blocks.

8. Repeat steps 2 to 7 to create a second F-runtime group.

9. After the "OK" button is activated in the "Edit F-Runtime Groups" dialog, the entries are saved and, following a prompt, any non-existing F-blocks are automatically created.

Safety-Related Communication between F-Runtime Groups of a Safety Program

Safety-related communication can take place between the two F-runtime groups of a safety program. That is, fail-safe data that are provided by an F-runtime group in an F-DB are read in another F-runtime group.

The "DB for F-Runtime Group Communication" is created in one of the following ways:

• In the "Define New F-Runtime Group" dialog (see above)

• In the "Edit F-Runtime Groups" dialog (see "Changing F-Runtime Groups") • In the SIMATIC Manager (see "Creating a DB for F-Runtime Communication in

SIMATIC Manager")

Note

The F-runtime group for which you furnished the F-DB can read and write to a DB for F-runtime group communication, while the "receiver" F-runtime group can only read this F-DB.

Tip: You can improve performance by structuring your safety program in such a

way that as few data as possible are exchanged between the F-runtime groups.

Creating a DB for F-Runtime Group Communication in SIMATIC Manager

You can create the DB for F-runtime communication in SIMATIC Manager in the same way as other F-DBs (see Creating and Editing an F-DB).

Note the following when creating the DB for F-runtime communication in SIMATIC Manager:

Assign the "RTG_DB" identifier in the "Family" field in the "General – part 2" tab of the F-DB object properties. This identifier designates the F-DB as a DB for

F-runtime group communication. Assign a symbolic name for the DB for the F-runtime group communication.

Updating Data Read from Another F-Runtime Group

Note

The data read are as old as the point in time when the F-runtime groups that made the data available completed processing before the start of the reading F-runtime group.

Assigning Fail-Safe Values

After the startup of the F-system, the F-runtime group reading data from the DB for F-runtime group communication of another F-runtime group (for example,

F-runtime group 2), fail-safe values are made available. The values you specified in the F-runtime group communication DB of F-runtime group 1 are provided as fail- safe values (default of the F-runtime group communication DB).

F-runtime group 2 reads the fail-safe values the first time it is initiated. The second time F-runtime group 2 is called, it reads the latest data if F-runtime group 1 has completed processing between the two calls for F-runtime group 2. If F-runtime group 1 has not completed processing, F-runtime group 2 continues to read the fail-safe values until F-runtime group 1 has completed processing.

The response is illustrated in the two figures below.

Reading data from F-runtime group 1 that has a longer OB cycle and lower priority than F-runtime group 2

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Reading data from F-runtime group 1 that has a shorter OB cycle and higher priority than F-runtime group 2

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F-runtime group providing data is not processed