Siemens SIMATIC ET 200AL, System Manual

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Open User Communication
6.2 Protocols for Open User Communication
Communication
Function Manual, 05/2021, A5E03735815-AJ
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6.2 Protocols for Open User Communication
Protocols for Open User Communication
The following protocols are available for open communication:
Table 6- 1 Transport protocols for open communication
Transport protocol Via interface
TCP according to RFC 793 PROFINET/Industrial Ethernet
ISO-on-TCP according to RFC 1006 (Class 4) PROFINET/Industrial Ethernet
ISO according to ISO/IEC 8073 Industrial Ethernet (only CP 1543-1)
UDP according to RFC 768 PROFINET/Industrial Ethernet
FDL PROFIBUS
Table 6- 2 Application protocols for open communication
Application protocol Used transport protocol
Modbus TCP TCP according to RFC 793
E-mail TCP according to RFC 793
FTP TCP according to RFC 793
TCP, ISO-on-TCP, ISO, UDP
Prior to data transfer, these protocols (except UDP) establish a transport connection to the
communications partner. Connection-oriented protocols are used when potential loss of data
needs to be avoided.
The following is possible with UDP:
•
Unicast to one device or broadcast to all devices on PROFINET via the PROFINET interface
of the CPU or the Industrial Ethernet interface of the CP 1543-1
• Multicast to all recipients of a multicast group via the PROFINET interface of the CPU* or
the PROFINET / Industrial Ethernet interface of the CP 1543-1
* As of firmware version V2.0, the PROFINET interface of the CPU supports a maximum of
5 multicast groups
Maximum user data length: You can find the maximum user data lengths supported in the
technical specifications of the respective device manuals.