Rtu Mode - Kruger Ecowatt Drive K120 Series Operation Manual

Ecowatt ® Drive K120 series
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)
Start bit BIT1
10-bit character frame (Bits 1 to 7 are data bits)
Start bit BIT1
32 #
Figure 7-3 Star connection
BIT2 BIT3 BIT4
BIT2 BIT3
1 #
15 #
BIT5 BIT6
BIT4 BIT5 BIT6
-127-
Communication protocol
Main
control
device
BIT7 BIT8 Check bit Stop bit
BIT7 Check bit Stop bit