IMO iDrive2 XKL Instruction Manual page 72

iDrive2 inverters
It is recommended to use shield cables and make the shield layer as the grounding wires during RS485 remote
communication.
In the cases with less devices and shorter distance, it is recommended to use 120Ω terminal resistor as the
performance will be weakened if the distance increase even though the network can perform well without load
resistor.
7.2.1.1 Single application
Figure 1 is the site Modbus connection figure of single inverter and PC. Generally, the computer does not have
RS485 interface, the RS232 or USB interface of the computer should be converted into RS485 by converter.
Connect the A terminal of RS485 to the 485+ terminal of the inverter and B to the 485- terminal. It is recommended
to use the shield twisted pairs. When applying RS232-RS485 converter, if the RS232 interface of the computer is
connected to the RS232 interface of the converter, the wire length should be as short as possible within the length
of 15m. It is recommended to connect the RS232-RS485 converter to the computer directly. If using USB-RS485
converter, the wire should be as short as possible, too.
Select a right interface to the upper monitor of the computer (select the interface of RS232-RS485 converter, such
as COM1) after the wiring and set the basic parameters such as communication baud rate and digital check bit to
the same as the inverter.
7.2.1.2 Multi-application In the real multi-application, the Daisy-chain connection and star connection are
commonly used.
Daisy-chain connection is required in the RS485 industrial fieldbus standards. The two ends are connected to
terminal resistors of 120Ω which is shown as figure 2. Figure 3 is the simply connection figure and figure 4 is the
real application figure.
Figure 3 is the star connection. Terminal resistor should be connected to the two devices which have the longest
distance. (1# and 15#device)
It is recommended to use shield cables in multiple connection. The basic parameter of the devices, such as baud
Figure 1 RS485 physical connection in single application
Figure 2 Daisy-chain connection applications
Figure 3 star connection
72
Communication protocol