Specifications
of the frequency converter when its internal PI controller is
used.
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 Setting
8-30 Protocol FC
8-31 Address 1 - 126
8-32 Baud Rate 2400 - 115200
8-33 Parity / Stop
Bits
Even parity, 1 stop bit (default)
7.4 FC Protocol Message Framing Structure
7.4.1 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.
0 1 32 4 5 6 7
195NA036.10
Start
bit
Even Stop
Parity bit
7.4.2 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)
A number of data bytes (variable, depending on the type
of telegram) follows.
A data control byte (BCC) completes the telegram.
STX LGE ADR DATA BCC
195NA099.10
7.4.3
Length (LGE)
The 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 LGE = 4 + 1 + 1 = 6 bytes
The length of telegrams with 12 data bytes is LGE = 12 + 1 + 1 = 14 bytes
The length of telegrams containing texts is 10
1)
+n bytes
1)
The 10 represents the fixed characters, while the “n’” is variable (depending on the length of the text).
7.4.4 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.
7.4.5 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.
7.4.6 The Data Field
The structure of data blocks depends on the type of . There are three types, and the type applies for both control telegrams
(master=>slave) and response telegrams (slave=>master).
RS-485 Installation and Set... VLT HVAC Basic Drive Design Guide
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