Technische Alternative UVR1611K-N, Руководство по установке

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Electrical connection
56
Cable selection and network topology
Screened
twisted pairs
have proven useful in CANopen networks. These are cables with twisted
pairs of conductors and a shared external screen. Such cables are relatively resistant to EMC inter-
ference and can still carry 50 kbit/s for up to 1000 m. The CANopen recommendations (CiA DR 303-
1) for cable cross-sections are given in the table below.
BUS length
[m]
Resistance in terms of
length [m Ω /m]
Cross-section
[mm²]
0…40 70 0.25…0.34
40…300 < 60 0.34…0.60
300…600 < 40 0.50…0.60
600…1000 < 26 0.75…0.80
The maximum cable length also depends on the number of nodes [n] linked with the BUS cable and
the cable cross-section [mm²].
Cable cross-section
[mm²]
Maximum length [m]
n=32 n=63
0.25 200 170
0.50 360 310
0.75 550 470
Recommendations
A 2x2-pole, screened twisted pair (twist CAN-L with CAN-H or +12 V with GND) with a cable cross-
section of at least 0.5 mm² and a conductor-to-conductor capacity of no more than 60 pF/m and a
nominal impedance of 120 ohms. The standard BUS speed of the UVR16x2 is 50 kbit/s. This recom-
mendation corresponds, for example, to cable type
Unitronic
®
- BUS CAN 2x2x0.5
supplied by
Lapp
Kabel
for permanent installation
in buildings or conduits.
Theoretically this would enable a BUS
length of approx. 500 m to guarantee reliable transmission.
For
direct
routing
underground
, earth cable
2x2x0.5
mm² supplied by
HELUKABEL
, part no.
804269, or earth cable
2x2x0.75
mm² supplied by
Faber Kabel
, part no. 101465, would be suitable.
Wiring
A CAN BUS network should never have a
star topology
. Rather, the correct topology is a line from
the first device (with terminator) to the second, third and so forth. The last bus device has the termina-
tion jumper again.
INCORRECT CORRECT