Design Guide | VLT® AutomationDrive FC 360
Table 30: Modbus Communication Parameter Settings (continued)
Parameter Function
Parameter 8-33 Parity/Stop Bits Set the parity and number of stop bits.
NOTICE
The default selection depends on the protocol selected in
parameter 8-30 Protocol.
Parameter 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.
Parameter 8-36 Maximum Response Delay Specify a maximum delay time between transmitting a request
and receiving a response.
Parameter 8-37 Maximum Inter-char delay If transmission is interrupted, specify a maximum delay time be-
tween 2 received bytes to ensure timeout.
NOTICE
The default selection depends on the protocol selected in
parameter 8-30 Protocol.
9.1.5 EMC Precautions
To achieve interference-free operation of the RS485 network, Danfoss recommends the following EMC precautions.
NOTICE
Observe relevant national and local regulations, for example, regarding protective ground connection. To avoid coupling of high
frequency noise between the cables, keep the RS485 communication cable away from motor and brake resistor cables. Normally,
a distance of 200 mm (8 in) is sufficient. Maintain the greatest possible distance between the cables, 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°.
9.2 FC Protocol
9.2.1 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 fieldbus.
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 telegram 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).
The physical layer is RS485, thus utilizing the RS485 port built into the drive. The FC protocol supports different telegram formats:
l A short format of 8 bytes for process data.
l A long format of 16 bytes that also includes a parameter channel.
Danfoss A/S © 2024.01 AJ435824192086en-000101 / 130R1295 | 91
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