Goodrive3000 series medium voltage VFD
Moudbus protocol
-193-
interfaces, so you need to convert an RS232 or USB interface of a PC to an RS485 interface through an adapter. Connect
end A of the RS485 interface to the 485+ port on the terminal block of the VFD, and connect end B to the 485- port. It is
recommended that you use shielded twisted pairs. When an RS232-RS485 adapter is used, the cable used to connect the
RS232 interface of the PC and the adapter cannot be longer than 15m. Use a short cable when possible. It is
recommended that you insert the adapter directly into the PC. Similarly, when a USB-RS485 adapter is used, use a short
cable when possible.
When the wiring is completed, select the correct port (for example, COM1 to connect to the RS232-RS485 adapter) for the
upper computer of the PC, and keep the settings of basic parameters such as communication baud rate and data check
bit consistent with those of the VFD.
VFD
Computer
Shielded twisted pair
485+
485-
Ground
B
A
Ground
B
A
RS485 line
RS232-RS485 converter
Figure 8-1 Wiring of RS485 applied to one VFD
8.3.1.2 Application to multiple VFDs
In pratical application to multiple VFDs, chrysanthemum connection and star connection are commonly used.
According to the requirements of the RS485 industrial bus standards, all the devices need to be connected in
chrysanthemum mode with one 120 Ω terminal resistor on each end, as shown in Figure 8-2. Figure 8-3 is the simplified
wiring diagram, and Figure 8-4 is the practical application diagram.
1#
2#
3#
4#
32#
120
Ω
120
Ω
Figure 8-2 On-site chrysanthemum link connection diagram
1#
2#
3#
31#
Master
A+
B-
A+
B-
Figure 8-3 Simplified chrysanthemum connection diagram
