3
vacon • 8 Modbus technical data
Local contacts: http://drives.danfoss.com/danfoss-drives/local-contacts/
3. MODBUS TECHNICAL DATA
3.1 Modbus RTU protocol
Table 2.
3.2 Modbus TCP protocol
Table 3.
3.3 Modbus UDP vs TCP
In addition to TCP, the VACON
®
100 family AC drive supports also UDP starting from following firm-
ware versions:
•VACON
®
100 INDUSTRIAL and VACON
®
100 X: FW0072V025
•VACON
®
100 FLOW: FW0159V016
•VACON
®
100 HVAC: FW0065V035
It is recommended that UDP is used when reading and writing rapidly and repetitively (cyclically)
the same data as in case of process data. TCP must be used for single operations, like service data
(e.g. reading or writing parameter values).
The key difference between UDP and TCP is that when using TCP, each and every Modbus frame
needs to be acknowledged by the receiver (see the figure below). This adds extra traffic to the net-
work and more load to the system (PLC and drives) because software needs to keep track of sent
frames to make sure that they have reached their destination.
Connections and
communications
Interface RS-485
Data transfer method RS-485 MS/TP, half-duplex
Transfer cable
STP (Shielded Twisted Pair), type Belden
9841 or similar
Connector
2.5 mm
2
Electrical isolation Functional
Modbus RTU
As described in “Modicon Modbus Proto-
col Reference Guide”
Bitrate
300, 600, 1200, 2400, 4800, 9600, 19200,
38400, 57600, 76800, 115200 and 230400
bits/s
Addresses 1 to 247
Connections and
communications
Interface 100BaseTX, IEEE 802.3 compatible
Data transfer method Ethernet half/full -duplex
Data transfer speed 10/100 MBit/s, autosensing
Protocol Modbus TCP
Connector Shielded RJ45 connector
Cable type CAT5e STP
Modbus TCP
As described in Modbus Messaging
Implementation Guide
Default IP Selectable: Fixed or DHCP (AutoIP)
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