Danfoss VLT AQUA Drive FC 202 Design Guide

the RS485 communication cable away from motor and
brake resistor cables to avoid coupling of high frequency
noise from one cable to another. Normally a distance of
200 mm (8 in) is sucient, but keeping the greatest
possible distance between the cables is recommended,
especially where cables run in parallel over long distances.
When crossing is unavoidable, the RS485 cable must cross
motor and brake resistor cables at an angle of 90°.
Fieldbus cable
Min. 200 mm
90° crossing
Brake resistor
130BD507.11
Figure 3.44 Cable Routing
3.8.5
FC Protocol Overview
The FC protocol, also referred to as FC bus or standard bus,
is the Danfoss standard serial communication bus. It
denes 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 master selects the individual
slaves via an address character in the message. A slave
itself can never transmit without rst 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 RS485, thus utilizing the RS485 port
built into the adjustable frequency drive. The FC protocol
supports
dierent message 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.
3.8.6 Network Conguration
Set the following parameters to enable the FC protocol for
the adjustable frequency drive:
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 3.26 FC Protocol Parameters
3.8.7
FC Protocol Message Framing
Structure
3.8.7.1 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.
Figure 3.45 Content of a Character
3.8.7.2 Message Structure
Each message has the following structure:
•
Start character (STX)=02 hex.
•
A byte denoting the message length (LGE).
•
A byte denoting the adjustable frequency drive
address (ADR).
A number of data bytes (variable, depending on the type
of message) follows.
System Integration
VLT
®
AQUA Drive FC 202
82 Danfoss A/S © 09/2014 All rights reserved. MG20N622
33

Danfoss VLT AQUA Drive FC 202 Specifications

General

Brand	Danfoss
Model	VLT AQUA Drive FC 202
Category	DC Drives
Language	English