TR-Electronic LA-46-K - 3.4 PROFINET IO - Services; 3.5 PROFINET IO

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04/23/2020 TR - ELA - BA - DGB - 0015 - 13 Page 61 of 92

3.4 PROFINET IO – Services

 Cyclic data exchange of process data

– RT communication within a network, no use of UDP/IP

– RT communication over UDP/IP (RT over UDP),

not supported at present

– IRT communication for deterministic and clock-synchronized data

transmission

– Multicast Communication Relation,

with RT- and IRT-communication based on the Provider/Consumer model,

not supported at present

 Acyclic data exchange of record data (read- / write services)

– Parameterization of the measuring system during system boot, writing of

preset value

– Reading of diagnostic information

– Reading of identification information according to the

„Identification and Maintenance (I&M) Functions“

– Reading of I/O data

3.5 PROFINET IO – Protocols

 DCP, Discovery and Control Program:

Assignment of IP addresses and device names over Ethernet

 LLDP, Link Layer Discovery Protocol: For topology identification

 SNMP, Simple Network Management Protocol: For network diagnostics

 MRP, Media Redundancy Protocol: For the ring topology check

and others

3.6 Distributed clocks

When spatially distributed processes require simultaneous actions, exact synchronization

of the subscribers in the network is necessary. For example in the case of applications in

which several servo axes must execute simultaneously coordinated sequences.

For this purpose the "Distributed clocks" function in accordance with standard IEEE 1588

is available in PROFINET IRT-Mode.

The master clock can exactly determine the runtime offset to the individual slave clocks,

and also vice-versa. The distributed clocks can be readjusted across the network on the

basis of this determined value. The jitter of this time base is below 1µs.

Distributed clocks can also be used efficiently for position detection, as they provide exact

information at a local time point of the data acquisition. Through the system, the accuracy

of a speed calculation no longer depends on the jitter of the communication system.

TR-Electronic LA-46-K - 3.4 PROFINET IO - Services; 3.5 PROFINET IO - Protocols; 3.6 Distributed clocks