Siemens SIMATIC S7-1500 Function Manual page 68

Protocol for communication via PROFIBUS: FDL
Data transfer via an FDL connection (Fieldbus Data Link) is suitable for the transfer of
related blocks of data to a communications partner on PROFIBUS that supports the sending
and receiving of data according to the FDL service SDA (Send Data with Acknowledge)
according to EN 50170, Vol 2. Both partners have the same rights; in other words, each
partner can initiate sending and receiving event-driven.
In keeping with the FDL service SDN (Send Data with No Acknowledge) according to
EN 50170, Vol 2, the following is possible with FDL:
● Broadcast to all devices on PROFIBUS via the PROFIBUS interface of the CM 1542-5
● Multicast to all recipients of a multicast group via the PROFIBUS interface of the
CM 1542-5
Modbus TCP
The Modbus protocol is a communication protocol with linear topology based on a
master/slave architecture. In the Modbus TCP (Transmission Control Protocol), the data is
transmitted as TCP/IP packets.
Communication is controlled solely by suitable instructions in the user program.
E-mail and FTP
You can use email to send for example, data block contents (e.g. process data) as an
attachment.
You can use the FTP connection (FTP = File Transfer Protocol) to transmit files to and from
S7 devices.
The communication is controlled by instructions in the user program at the client end.
Application example: MQTT Publisher for the SIMATIC S7-1500 CPU
The "Message Queue Telemetry Transport" (MQTT) is a simple protocol on the TCP/IP
level. It is suitable for the exchange of messages between devices with lower functionality
and for the transfer via unreliable networks.
The application example provides a function block with which you can implement the MQTT
protocol into the SIMATIC S7-1500.
You can find the application example on the Internet
(https://support.industry.siemens.com/cs/ww/en/view/109748872).
Communication
Function Manual, 11/2019, A5E03735815-AH
Open User Communication
6.2 Protocols for Open User Communication
67