Danfoss VLT FC51, Руководство по конструкции, Страница: 68 / 94

8.1.4 EMC Precautions
The following EMC precautions are recommended in order
to achieve interference-free operation of the RS-485
network.
Relevant national and local regulations, for example
regarding protective earth connection, must be observed.
Keep the RS-485 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 inches) is sufficient, but keeping the
greatest possible distance between the cables is generally
recommended, especially where cables run in parallel over
long distances. When crossing is unavoidable, the RS-485
cable must cross motor and brake resistor cables at an
angle of 90
°
.
Fieldbus cable
Brake resistor
Min.200mm
90° crossing
130BC010.10
Illustration 8.3 EMC Precautions for RS-485
8.1.5 Frequency Converter Parameter
Settings for Modbus Communication
The following parameters apply to the RS-485 interface
(FC-port):
Parameter Function
8-30 Protocol Select the application protocol to run on
the RS-485 interface
8-31 Address Set the node address.
NOTICE
The address range depends on the
protocol selected in
8-30 Protocol
8-32 Baud Rate Set the baud rate.
NOTICE
The default baud rate depends on the
protocol selected in
8-30 Protocol
8-33 Parity / Stop
Bits Set the parity and number of stop bits.
NOTICE
The default selection depends on the
protocol selected in
8-30 Protocol
8-35 Minimum
Response Delay Specify a minimum delay time between
receiving a request and transmitting a
response. This function is for overcoming
modem turnaround delays.
8-36 Maximum
Response Delay Specify a maximum delay time between
transmitting a request and receiving a
response.
Table 8.2 Parameters Related to RS-485 Interface
8.2 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-follower principle for
communications via a serial bus.
One master and a maximum of 126 followers can be
connected to the bus. The master selects the individual
followers via an address character in the telegram. A
follower itself can never transmit without first being
requested to do so, and direct message transfer between
the individual followers is not possible. Communications
occur in the half-duplex mode.
The master function cannot be transferred to another node
(single-master system).
RS-485 Installation and Set...
VLT
®
Micro Drive FC 51 Design Guide
66 MG02K302 - Rev. 2013-12-03
8 8