Rtu Mode - INVT Goodrive100 Series Instruction Manual

Goodrive100 inverters

7.3 RTU mode

7.2.2.1 RTU communication frame format
If the controller is set to communicate by RTU mode in Modbus network every 8bit byte in the message
includes two 4Bit hex characters. Compared with ACSII mode, this mode can send more data at the same
baud rate.
Code system
· 1 start bit
· 7 or 8 digital bit, the minimum valid bit can be sent firstly. Every 8 bit frame includes two hex characters
(0...9, A...F)
· 1 even/odd check bit . If there is no checkout, the even/odd check bit is inexistent.
· 1 end bit (with checkout), 2 Bit(no checkout)
Error detection field
· CRC
The data format is illustrated as below:
11-bit character frame (BIT1~BIT8 are the digital bits)
Start bit BIT1
10-bit character frame (BIT1~BIT7 are the digital bits)
Start bit BIT1
In one character frame, the digital bit takes effect. The start bit, check bit and end bit is used to send the
BIT2 BIT3 BIT4
BIT2 BIT3
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Communication protocol
BIT5 BIT6
BIT4 BIT5 BIT6
Check
BIT7 BIT8
bit
Check
BIT7
bit
End bit
End bit