The adjustable frequency drive protocol, also referred to as adjustable frequency drive bus or standard bus, is the Danfoss standard serial communication
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
message. 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 adjustable frequency drive. The adjustable frequency protocol supports different
message 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 message
format is used for texts.
7.3 Network Configuration
7.3.1 FC 300 Adjustable Frequency Drive Set-up
Set the following parameters to enable the Adjustable Frequency protocol for the adjustable frequency drive.
Parameter Number
Setting
Par. 8-30
Protocol
FC
Par. 8-31
Address
1 - 126
Par. 8-32
FC Port Baud Rate
2400 - 115200
Par. 8-33
Parity / Stop Bits
Even parity, 1 stop bit (default)
7 RS-485 Installation and Set-up
VLT HVAC Low Harmonic Drive Instruction
Manual
7-4
MG.16.A1.22 - VLT
®
is a registered Danfoss trademark
7
