8
Configuration and startup of Modbus/TCP
Project planning examples
Manual – MOVIPRO
®
with EtherNet/IP™ or Modbus/TCP Fieldbus Interface
95
8.4.2 Data exchange via Modbus/TCP
As there are many fieldbus master systems and software solutions available for Mod-
bus/TCP for standard PCs, there is not "one reference controller" the examples are
based on. This chapter gives detailed examples regarding the telegram structure.
INFORMATION
The telegram structure from the examples can be used for troubleshooting in case of
errors in the telegram structure in your own applications. There are simple tools for
recording telegrams via the Ethernet network, e.g. Wireshark, Packetizer etc. These
freeware tools are available on the Internet.
Tracing all Ethernet telegrams in a single network is possible only with a tab, hub or a
switch with a port mirror function. Telegrams that are sent from and to the recording
PC can always be written.
The following figure provides an example of how setpoints are written (FC16) to the
Modbus/TCP slave with IP address 10.3.71.119. The 3 process data words are loc-
ated from offset 4 (reference number) and are addressed via device ID 255.
9007201560597131
All the other examples merely describe the Modbus/TCP part of the telegram. The
TCP/IP part of the telegram, as well as establishing and dropping a TCP/IP connection
are not explained in detail.
16998413/EN – 12/2016
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