Siemens SINAUT ST7 System Manual page 65

Note
Since the SINAUT modems MD2, MD3 and MD4 do not have an S7-300 backplane bus, an
S7-300 SM, FM or CP module that communicates with the CPU over this backplane bus
must not be inserted to the right of the modem!
Note
In all of the sample configurations of the S7-300, it is assumed that a 24 V power supply is
available for the CPU, the TIMs and the other modules.
Note
Direct connection of a TIM 3V-IE variant to the PROFINET interface of an S7-300-CPU is not
possible!
S7-300 with access to a classic WAN
To implement classic WAN access for an S7-300, you can use either a TIM 3V-IE or a
TIM 3V-IE Advanced. The following figure shows such a configuration.
Figure 3-11
Other modems with an RS-232 interface can also be used, for example wireless devices or
the MODEM MD720.
SINAUT ST7 - Volume 1
System Manual, 11/2018, C79000-G8976-C178-12
Network structures, configuration examples, installation guidelines
SIMATIC S7-300 with TIM 3V-IE with 1 connection to classic WAN over an external
modem.
3.3 Installation guidelines and compatible CPUs
65