Rs485: Fc Protocol Overview - Danfoss VLT AutomationDrive FC 361 Series Design Manual

Appendix
11.3.1 EMC Precautions
To achieve interference-free operation of the RS485
network, the following EMC precautions are recommended.
Relevant national and local regulations regarding
protective ground connection, for example, must be
observed. The RS485 communication cable must be kept
away from motor and brake resistor cables to avoid
coupling of high-frequency noise from 1 cable to another.
Normally a distance of 200 mm (8 in) is sufficient. However,
in situations where cables run in parallel over long
distances, keeping the greatest possible distance between
cables is recommended. When crossing is unavoidable, the
RS485 cable must cross motor and brake resistor cables at
an angle of 90°.
Fieldbus cable
11 11
Minimum
(2000 mm (78.7 in))
90° crossing
Illustration 11.4 EMC Precautions
78
VLT® AutomationDrive FC 361

11.4 RS485: FC Protocol Overview

11.4.1 FC Protocol Overview
The FC protocol, also referred to as FC bus or standard bus,
is the Danfoss standard fieldbus. It defines an access
technique according to the master/slave principle for
communications via a field 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 telegram. The 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 RS485, thus utilizing the RS485 port
built into the drive. The FC protocol supports different
telegram formats:
•
•
•
11.4.2 Drive Set-up
Set the following parameters to enable the FC protocol for
the drive.
Parameter number
Parameter 8-30 Protocol
Parameter 8-31 Address
Parameter 8-32 FC Port
Baud Rate
Parameter 8-33 Parity /
Stop Bits
Table 11.3 FC Protocol Parameters
Danfoss A/S © 03/2019 All rights reserved.
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.
Setting
FC
1–126
2400–115200
Even parity, 1 stop bit (default)
MG06K102