INVT Goodrive390L Series User Manual page 67

Goodrive390L Series Lift-Dedicated VFD
Figure 7-4 Practical chrysanthemum connection application
Shield twisted pair
RS232–RS485
Converter
Max. cable length:
GND
PC
Figure 7-5 shows the start connection diagram. When this connection mode is adopted,
each of the two devices that are farthest away from each other on the line must be
configured with a terminal resistor (in this figure, the two devices are devices 1# and 15#).
Use shielded cables, if possible, in multi-device connection. The baud rates, data bit
check settings, and other basic parameters of all the devices on the RS485 line must be
set consistently, and addresses cannot be repeated.
7.1.1.2 RTU mode
7.1.1.2.1 RTU communication frame structure
When a controller is set to use the RTU communication mode on a Modbus network,
every byte (8 bits) in the message includes 2 hexadecimal characters (each includes 4
bits). Compared with the ASCII mode, the RTU mode can transmit more data with the
same baud rate.
Code system
• 1 start bit
• 7 or 8 data bits; the minimum valid bit is transmitted first. Each frame domain of 8 bits
includes 2 hexadecimal characters (0–9, A–F).
202403 (V1.0）
485 +
485 -
Ground
VFD
15m
Address 1
Figure 7-5 Star connection
1#
32#
485 +
485 -
Ground
VFD
Address 2
15#
Communication protocol
485 +
485 -
Ground
120Ω
terminal
resistor
VFD
n
Address
59