Network Configuration; Fc Protocol Message Framing Structure - Fc - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide
The FC protocol, also referred to as FC bus or Standard bus, is the Danfoss Drives standard field-
bus. It defines an access technique according to the master-slave principle for communications
via a serial bus.
One master and a maximum of 126 slaves can be connected to the bus. The individual slaves are
selected by the master via an address character in the telegram. A slave itself can never transmit
without first being requested to do so, and direct message transfer between the individual slaves
is not possible. Communications occur in the half-duplex mode.
The master function cannot be transferred to another node (single-master system).
The physical layer is RS-485, thus utilizing 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, and
a long format of 16 bytes that also includes a parameter channel. A third telegram format is used
for texts.

9.3. Network Configuration

9.3.1. FC 300 Frequency Converter Set-up
Set the following parameters to enable the FC protocol for the FC 300.
Parameter
ber
8-30
8-31
8-32
8-33

9.4. FC Protocol Message Framing Structure - FC 300

9.4.1. 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, 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.
Num- Parameter name
Protocol
Address
Baud Rate
Parity/Stop bits
MG.33.B9.02 - VLT ® is a registered Danfoss trademark
9. RS-485 Installation and Set-up
Setting
FC
1 - 126
2400 - 115200
Even parity, 1 stop bit (default)
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