Network Configuration; Fc Protocol Message Framing Structure; Content Of A Character (Byte); Telegram Structure - Danfoss VLT DriveMotor FCP 106 Programming Manual

RS-485 Installation and Set...
•
Reset after a fault trip
•
Run at various preset speeds
•
Run in reverse
•
Change of the active set-up
•
Control of the 2 relays built into the frequency
converter
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. This permits a
range of control options, including controlling the setpoint
of the frequency converter when its internal PI controller is
used.

3.3 Network Configuration

3.3.1 Frequency Converter Set-up
Set the following parameters to enable the FC protocol for
the frequency converter.
Parameter Setting
8-30 Protocol FC
Parameter 8-31 Address 1-126
Parameter 8-32 Baud 2400-115200
Rate
Parameter 8-33 Parity / Even parity, 1 stop bit (default)
Stop Bits
Table 3.3 Network Configuration Parameters

3.4 FC Protocol Message Framing Structure

3.4.1 Content of a Character (byte)

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. This bit is set at "1"
when it reaches parity. Parity is when there is an equal
number of 1s in the 8 data bits and the parity bit in total.
A stop bit completes a character, thus consisting of 11 bits
in all.
Start 0 1 2 3 4
bit
Illustration 3.5 Content of a Character

3.4.2 Telegram Structure

Each telegram has the following structure:
1. Start character (STX)=02 hex
2. A byte denoting the telegram length (LGE)
®
VLT DriveMotor FCP 106 and FCM 106 Programming Guide
5 6 7 Even Stop
Parity bit
MG03N102 - Rev. 2013-12-02
3. A byte denoting the frequency converter address
(ADR)
A number of data bytes (variable, depending on the type
of telegram) follows.
A data control byte (BCC) completes the telegram.
STX LGE ADR
Illustration 3.6 Telegram Structure

3.4.3 Telegram Length (LGE)

The telegram length is the number of data bytes plus the
address byte ADR and the data control byte BCC.
4 data bytes
12 data bytes
Telegramscontaining texts
Table 3.4 Length of Telegrams
1)
The 10 represents the fixed characters, while the "n'" is variable
(depending on the length of the text).

3.4.4 Frequency Converter Address (ADR)

Address format 1-126
Bit 7=1 (address format 1-126 active)
Bit 0-6=frequency converter address 1-126
Bit 0-6=0 Broadcast
The follower returns the address byte unchanged to the
master in the response telegram.

3.4.5 Data Control Byte (BCC)

The checksum is calculated as an XOR-function. Before the
first byte in the telegram is received, the calculated
checksum is 0.
DATA BCC
LGE=4+1+1=6 bytes
LGE=12+1+1=14 bytes
1)
10 +n bytes
19
3 3