Goodrive30 Series VFD Communication protocol
-125-
1 #
15#
32 #
6
#
Main
control
device
Figure 7-3 Star connection
Use shielded cables, if possible, in multi-VFD 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.
7.2.2 RTU mode
7.2.2.1 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 help to send more data at the same baud
rate.
Code system
• 1 start bit
• 7 or 8 data bits; the minimum valid bit is sent first. Each frame domain of 8 bits includes 2
hexadecimal characters (0–9, A–F).
• 1 odd/even check bit; this bit is not provided if no check is needed.
• 1 stop bit (with check performed), or 2 bits (without check)
Error detection domain
• Cyclic redundancy check (CRC)
The following table describes the data format.
11-bit character frame (Bits 1 to 8 are data bits)
10-bit character frame (Bits 1 to 7 are data bits)
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