The master function cannot be transferred to another node
(single-master system).
The physical layer is RS-485, thus utilising the RS-485 port
built into the frequency converter. The FC protocol
supports different telegram formats:
•
A short format of 8 bytes for process data
•
A long format of 16 bytes that also includes a
parameter channel
•
A format used for texts
12.6 Network Configuration
12.6.1 Frequency Converter Set-up
Set the following parameters to enable the FC protocol for
the frequency converter.
Parameter Number
Setting
8-30 Protocol
FC
8-31 Address
1-126
8-32 FC Port Baud Rate
2400-115200
8-33 Parity / Stop Bits
Even parity, 1 stop bit (default)
Table 12.2 FC Protocol Parameters
12.7 FC Protocol Message Framing
Structure
12.7.1 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
3
2
4
5
6
7
195NA036.10
Start
bit
Even Stop
Parity bit
Illustration 12.5 Content of a Character
12.7.2 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
Illustration 12.6 Telegram Structure
12.7.3 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
LGE=4+1+1=6 bytes
12 data bytes
LGE=12+1+1=14 bytes
Telegramscontaining texts
10
1)
+n bytes
Table 12.3 Length of Telegrams
1) The 10 represents the fixed characters, while the “n’” is variable
(depending on the length of the text).
12.7.4 Frequency Converter Address (ADR)
2 different address formats are used.
The address range of the frequency converter is either 1-31
or 1-126.
1. Address format 1-31:
Bit 7 = 0 (address format 1-31 active)
Bit 6 is not used
Bit 5 = 1: Broadcast, address bits (0-4) are not
used
Bit 5 = 0: No Broadcast
Bit 0-4 = frequency converter address 1-31
2. 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.
12.7.5 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.
RS-485 Installation and Set...
VLT
®
AutomationDrive FC 301/FC 302 Design Guide, 0.25-75 kW
178
MG33BF02 - Rev. 2013-12-20
12
12