Functions
5.12 Accelerating startup
PROFINET with STEP 7 V15
252 Function Manual, 12/2017, A5E03444486-AH
● Configured RT class of the IO device
Note
Startup time and RT class of the IO device
An IO device with IRT communication requires
longer than an IO device with RT
communication for the accelerated startup.
The longer startup for IRT is due to the necessity of synchronizing the IO device before
the communication can be set up.
Note
IWLAN and prioritized startup
PROFINET devices
which are connected via access points to PROFINET IO do not
support the "Prioritized startup" PROFINET function.
Prioritized startup
Definition
Prioritized startup refers to the PROFINET function for accelerating the startup of IO devices
in a PROFINET IO system with RT communication. It shortens the time that the respective
configured IO devices require in order to reach the cyclic user data exchange in the following
cases:
● After the power supply has returned
● After a station has returned
● After activation of IO devices
Data exchange despite multiple use IP addresses/device names in PROFINET IO system
To achieve higher ramp-up times, the IO controller checks the uniqueness of device name
of IP address parallel to the device ramp-up. In the case of incorrect or double assignment
of device name or IP address, a short-time data exchange is possible until the IO controller
reacts to the error. In this time the IO controller can exchange IO data with the false device.
During commissioning, ensure that no IP addresses / device names are assigned multiple
times in the PROFINET IO system.
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