Telegram Structure; Frequency Converter Address (Adr); Data Control Byte (Bcc) - Danfoss VLT DriveMotor FCP 106 Programming Manual

RS485 Installation and Set-...

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).
3. A byte denoting the frequency converter address
(ADR).
Several data bytes (variable, depending on the type of
telegram) follow.
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
Telegrams containing texts
Table 3.4 Length of Telegrams
1) The 10 is 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 slave 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.
MG03N202
Programming Guide
DATA BCC
LGE=4+1+1=6 bytes
LGE=12+1+1=14 bytes
1)
10 +n bytes
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