Network Configuration; Fc Protocol Message Framing Structure - Danfoss VLT HVAC Drive FC 100 Series Design Manual

7. RS-485 Installation and Set-up

7.3. Network Configuration

7.3.1. Frequency Converter Set-up
Set the following parameters to enable the FC protocol for the frequency
converter.
Parameter Number
8-30
8-31
8-32
8-33

7.4. FC Protocol Message Framing Structure

7.4.1. Content of a Character (byte)
7
Each character transferred begins with a start bit. Then 8 data bits are transferred, corresponding to a byte. Each character is secured via a parity bit,
which is set at "1" when it reaches parity (i.e. when there is an equal number of 1's in the 8 data bits and the parity bit in total). A character is completed
by a stop bit, thus consisting of 11 bits in all.
7.4.2. Telegram Structure
Each telegram begins with a start character (STX)=02 Hex, followed by a byte denoting the telegram length (LGE) and a byte denoting the frequency
converter address (ADR). A number of data bytes (variable, depending on the type of telegram) follows. The telegram is completed by a data control
byte (BCC).
7.4.3. Telegram Length (LGE)
The telegram length is the number of data bytes plus the address byte ADR and the data control byte BCC.
The length of telegrams with 4 data bytes is
The length of telegrams with 12 data bytes is
The length of telegrams containing texts is
1) The 10 represents the fixed characters, while the "n'" is variable (depending on the length of the text).
130
Parameter Name Setting
Protocol FC
Address 1 - 126
Baud Rate 2400 - 115200
Parity/Stop bits Even parity, 1 stop bit (default)
MG.11.B7.02 - VLT ® is a registered Danfoss trademark
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VLT HVAC Drive Design Guide
LGE = 4 + 1 + 1 = 6 bytes
LGE = 12 + 1 + 1 = 14 bytes
10 1) +n bytes