14.3.7 Communication Networking
Networking
The communication network is shown in figure below, with a PC, a PLC or an ex-
ternal computer as the master and all frequency converters as slaves, which are
connected by shielded twisted pair cables. The slave at the end of the network
needs a termination resistor with recommended value of 120 Ω, 0.25 W.
Fig. 14-1: Communication networking
●
The maximum length of the communication cable is 300 m.
●
The maximum length of the communication cable is 80 m if the
number of slaves is less than 5.
●
If the Modbus network cannot work successfully, check if a bias
resistor has been installed for the master device and make sure
that its resistance is not more than 1.5 kΩ.
WARNING
Cables may only be connected when the frequency converters are switched off!
Recommendations on networking
●
Use shielded twisted pair cable to connect RS485 links.
●
Modbus cable should be adequately away from power cables (minimum 30
cm).
●
Avoid crossing of Modbus cables and power cables and use orthogonal cross-
ing if crossing must be used.
●
The shielding layer of cables should be connected to protected ground or to
equipment ground if the equipment ground has already been connected to
protected ground. Do not directly ground any point of the RS485 network.
●
In no circumstance should ground cables constitute a loop.
Bosch Rexroth AG
Communication
EFC x610 Series
274/389
DOK-RCON03-EFC-X610***-IT05-EN-P
