Siemens SIMATIC NET Especificações descarregar pdf (Página 34)

24 Siemens Simatic S7 Driver Online Help

Choosing Poll Rates

Make the datablock’s poll rate faster than the scan time. For example, if you have a

database block with a 5-second scan time, set the poll rate of the datablock it accesses

to 2 or 3 seconds.

Keep in mind that if you set datablock poll rates to values that are faster than needed,

you impose unnecessary stress on your system.

Zero and Subsecond Poll Rates

You can set the poll rate to zero or to a subsecond value from 0.1 and 0.9. For

example, you could set the poll rate to 0.5. Setting the poll rate to zero or a subsecond

value disables overruns. Entering a zero poll rate also forces the driver to run at its

maximum rate. In general, you should set the poll rate to less than 1, if it is more

important to run the driver at a fast speed than to detect overruns. If you plan to use a

poll rate less than 1, make sure your process hardware supports subsecond values.

See Also

Understanding Datablock Timing Properties: Rate, Phase, and Access Time | Using

Primary and Secondary Poll Rates with Access Time

Eliminating Excess Datablocks

If you enabled the Auto Create option in your driver configuration and created new

datablocks from Database Manager, you may have excess datablocks that you want to

remove. Use the following procedure to eliminate any incorrectly configured or

unused (excess) datablocks.

Using the Auto Create option also adds datablocks with default values. If you have

modified the poll rate or access time of one or more datablocks, use the procedure at

the end of this topic.

NOTE: You may not be able to delete datablocks from the driver configuration

because another computer may start accessing them.

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Siemens SIMATIC NET Especificações Página 34