Configuring Hardware and Communication Connections STEP 7.pdf

Configuring PROFINET IO Devices
4.1.6 Setting a Specific Update Time for an IO-Device
Procedure
Tip
With STEP 7 V5.3, Service Pack 1, you can set an update time that applies to all
IO devices in a PROFINET IO system. In this case, the slowest IO device will
determine the update time, even if shorter update times would be possible for
individual IO devices.
As of STEP 7 V5.3, Service Pack 2, you have the option of setting separate update
times for individual IO devices. This option is called "Set a specific update time for
an IO device". The option of setting a uniform update time for all IO devices is still
available. This option is called "Set update time for all IO systems".
1. Double-click the IO system (the "railroad track").
2. Select the "Update Time" tab.
- If, in addition to PROFINET IO, other cyclical services (i.e. from
Component-based Automation, CBA) have to be taken into consideration:
Go to the "Communication Component (PROFINET IO)" field and select a
percentage that should be reserved for PROFINET IO.
If at least one IO device is configured, then the default setting is 100%.
If no IO device is configured, then the default setting is 0%.
- Select the "Set a specific update time for an IO device" (if it is not already
selected by default).
- The IO devices are listed in the field below. STEP 7 has already calculated
an optimal update time for each IO device.
The update times for IO devices that do not exchange user data (e.g. a
switch) are identified with an asterisk (*). As a rule, the update times for
these PROFINET devices are higher than those for the remaining IO
devices.
- If necessary, sort the information displayed in a column by clicking the
column header. To display the information in the opposite sequence, click
the column header again
- To change the update time, double-click the row with the desired device
number.
To set the update time at once for several IO devices, select the IO devices
concerned (multiple selection) and click the "Edit" button". To select multiple
devices, you can select each one in sequence while holding the CTRL key down.
Optimizing the update times for individual IO devices
Based on the configuration, STEP 7 calculates the optimized (the shortest
possible) update times. However, by increasing the update times for individual IO
devices that supply data that do not have to be absolutely available at a definite
time (not time-critical), you can expand the leeway available in order to allow
shorter update times for other IO devices.
Configuring Hardware and Communication Connections with STEP 7
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