Comparison Of Rt And Irt; Configuring Profinet Io With Irt - Siemens SIMATIC PROFINET Function Manual

Functions
5.5 Real-time communication
5.5.4

Comparison of RT and IRT

The most important differences between RT and IRT
Table 5- 2 Comparison between RT and IRT
Property
Transmission method
Determinism
Hardware support through special
Ethernet controllers is required
Isochronous application
Starting time of the isochronous
application
5.5.5

Configuring PROFINET IO with IRT

Introduction
If you want to configure a PROFINET IO system with IRT, you have to configure the
PROFINET IO devices. These PROFINET devices must support IRT. Set which device acts
as the sync master and synchronizes the other devices. This is done by configuring a sync
domain with a sync master and at least one sync slave.
Requirement
● There is an IO system with an IO controller and at least one IO device.
● You have configured the topology for the IO system.
● The devices support IRT.
162
RT
Prioritizing the RT frames through Ethernet
priority (VLAN tag)
Variance of the duration of transmission by
the shared use of the transmission band-
width with other protocols (e.g., TCP/IP)
Not required
-
-
IRT
Path-based switching on the basis of a
communication path plan; no transmis-
sion of TCP/IP frames in the time range
with IRT communication.
Exact, planned transmission, transmis-
sion and reception times are guaranteed
for all topologies.
Required
Yes
The point in time for the reception of the
data is planned exactly. Application can
be started synchronized to the cycle.
PROFINET with STEP 7 V14
Function Manual, 09/2016, A5E03444486-AG