5
Communication
5.1
Modbus slave interface
The PLC can communicate with a control system using the RS-232 Modbus slave interface. To-
gether with the suitable process visualization software and communication software, a com-
plete control system can be implemented.
The following interface settings are possible:
–
Operation with a dial-up modem on the RS-232 Modbus slave interface
Basically, communication is only established automatically when the application has been con-
figured to dial when a fault occurs. The controller works autonomously. Nevertheless, the mo-
dem can dial up to the controller at any time to read data from it or change settings, if neces-
sary. The use of the modem connecting cable (1400-7139) is recommended.
–
Operation with a leased line modem on the RS-232 Modbus slave interface
Communication is established over a permanent connection between two leased line modems.
This setup is applied for long-distance transmissions or when different signal level converters
are used. The connection between the controller and the modem can also be established over
the modem connecting cable (1400-7139).
–
Operation on a four-wire bus
To link the controller and the bus line, the signal level needs to be converted by an appropriate
converter (SAMSON cable converter 1400-7308).
18
EB 5571 EN
Communication
Fig. 1 · Network structure
Summary of Contents for TROVIS 5571
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