NVF5 Series User Manual Appendix A RS485-MODBUS
Communication Instructions
Appendix A RS485-MODBUS Communication
Instructions
A.1 Networking Mode
NVF5 inverter provides RS485 communication interface and adopts the international
standard Modbus communication protocol for Master-Slave communication. Users can
achieve centralized control (set the control command and running frequency of inverter,
modification of the related parameters, monitoring of inverter status and fault information
etc.) through PC/PLC, host computer monitoring software etc., to adapt to the specific
application requirements.
As shown in figure A-1-1
，
the networking modes of NVF5 (as the slave station) include
single master/ multiple slaves mode and single master/ single slave mode.
Inverter
Host
（
PLC
）
Host
（
PC
）
Host
（
PLC
）
Adapter
RS232/RS485
RS232
Adapter
RS232/RS485
RS232
Inverter
Inverter
Inverter
Inverter
Inverter
Inverter
Host
（
PC
）
RS485
RS485
RS485
...
Figure A-1-1 Networking Mode Diagram
A.2 Interface Mode
RS485 interface: Asynchronous, half-duplex. Default: 1-8-N-2
（
Bit 1-start bit; bit
8-data bit, no check, bit 2-stop bit, 9600bps, RTU, slave address: 0x01. For parameter
setting, see description of Parameter List Group Fb .
A.3 Communication Mode
1
．
Inverter communication protocol is Modbus protocol, and supports RTU and ASCII
protocols.
2
．
The inverter is the slave and adopts master-slave point-to-point communication.
When the master send commands using the Broadcast mode, the slave will not respond.
3
．
In the case of multi-machine communication or long-distance, connecting
Termination resistors of (100 to 120) ohm on the positive and negative terminals of the
signal line of master station communication which can improve the communication
immunity.
4
．
The inverter only provides one RS485 interface. If the communication port for
peripheral equipment is RS232, RS232/RS485 conversion equipment should be added.
- 101 -
