Devicenet Network Installation; Baud Rate; Address In The Devicenet Network; Termination Resistor - WEG DeviceNet CFW500 User Manual

3 DEVICENET NETWORK INSTALLATION

The DeviceNet network, such as several industrial communication networks, for being many times applied in
aggressive environments with high exposure to electromagnetic interference, requires that certain precautions
be taken in order to guarantee a low communication error rate during its operation. Recommendations to
perform the connection of the product in this network are presented next.
3.1

BAUD RATE

Equipments with DeviceNet interface generally allow the configuration of the desired baud rate, ranging from
125Kbit/s to 500Kbit/s. The
in the installation. The next table shows the baud rates and the maximum cable length that can be used in the
installation, according to the ODVA recommendation
All network equipment must be programmed to use the same communication baud rate. At the CFW500
frequency converter the baud rate configuration is done through the parameter P0702.
3.2

ADDRESS IN THE DEVICENET NETWORK

Each DeviceNet network device must have an address or MAC ID, and may range from 0 to 63. This address
must be unique for each equipment. For CFW500 frequency converter the address configuration is done
through the parameter P0701.
3.3

TERMINATION RESISTOR

The CAN bus line must be terminated with resistors to avoid line reflection, which can impair the signal and
cause communication errors. The extremes of the CAN bus must have a termination resistor with a 121Ω /
0.25W value, connecting the CAN_H and CAN_L signals.
3.4

CABLE

The connection of CAN_L and CAN_H signals must done with shielded twisted pair cable. The following table
shows the recommended characteristics for the cable.
It is necessary to use a twisted pair cable to provide additional 24Vdc power supply to equipments that need
this signal. It is recommended to use a certified DeviceNet cable.
3.5

CONNECTION IN THE NETWORK

In order to interconnect the several network nodes, it is recommended to connect the equipment directly to the
main line without using derivations. During the cable installation the passage near to power cables must be
avoided, because, due to electromagnetic interference, this makes the occurrence of transmission errors
possible. In order to avoid problems with current circulation caused by difference of potential among ground
connections, it is necessary that all the devices be connected to the same ground point.
5 Different products may have different maximum allowed cable length for installation.
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baud rate that can be used by equipment depends on the length of the cable used
Table 3.1: Supported baud rates and installation size
Baud Rate
500 Kbit/s
250 Kbit/s
125 Kbit/s
Table 3.2: DeviceNet cable characteristics
Cable length Resistance per
(m) meter (mOhm/m)
0 ... 40 70
40 ... 300 <60
300 ... 600 <40
600 ... 1000 <26
.
5
Cable Length
100 m
250 m
500 m
Conductor cross
section (mm2)
0.25 ... 0.34
0.34 ... 0.60
0.50 ... 0.60
0.75 ... 0.80