•
•
-
-
-
-
•
•
•
•
•
•
•
•
•
Start.
Various stops:
Coast stop.
Quick stop.
DC brake stop.
Normal (ramp) stop.
Reset after a fault trip.
Run at various preset speeds.
Run in reverse.
Change the active set-up.
Control built-in relay of the drive.
The bus reference is commonly used for speed control. It is also possible to access the parameters, read their values, and, where
possible, write values to them. Accessing the parameters offers a range of control options, including controlling the setpoint of the
drive when its internal PI controller is used.
8.7 Network Configuration
To enable Modbus RTU on the drive, set the following parameters:
Table 59: Network Configuration
Parameter
Setting
Parameter 8-30 Protocol
Modbus RTU
Parameter 8-31 Address
1–247
Parameter 8-32 Baud Rate
2400–115200
Parameter 8-33 Parity/Stop Bits
Even parity, 1 stop bit (default)
8.8 Modbus RTU Message Framing Structure
8.8.1 Modbus RTU Message Byte Format
The controllers are set up to communicate on the Modbus network using RTU (remote terminal unit) mode, with each byte in a
telegram containing 2 4-bit hexadecimal characters. The format for each byte is shown in the following tables.
Table 60: Format for Each Byte
Start bit
Data byte
Stop/ parity
Stop
Table 61: Byte Details
Coding system
8-bit binary, hexadecimal 0–9, A–F.
2 hexadecimal characters contained in each 8-bit field of the telegram.
Bits per byte
1 start bit.
8 data bits, least significant bit sent first.
1 bit for even/odd parity; no bit for no parity.
1 stop bit if parity is used; 2 bits if no parity.
Error check field
Cyclic redundancy check (CRC).
AJ363928382091en-000101 / 130R0983
112 | Danfoss A/S © 2021.04
RS485 Installation and Set-up
VLT® Flow Drive FC 111
Design Guide