Electrical installation
Wiring of system bus (CAN)
85
EDBCSXS064 EN 4.0
Example: Selection help
Specifications
l
Cable cross−section:
0.5 mm
2
(according to cable specifications
l
Number of nodes:
63
l
Repeater:
Lenze−repeater, type 2176 (cable reduction: 30 m)
For the max. number of nodes (63), the following cable lengths / number of repeaters from
the specifications must be observed:
Baud rate
[kbit/s]
50
120
250
500
1000
Max. cable length
[m]
1500
630
290
120
25
Segment cable length
[m]
310
310
290
120
25
Number of repeaters
5
2
−
−
−
Check repeater application
Given:
l
Baud rate:
125 kbps
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Cable cross−section:
0.5 mm
2
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Number of nodes:
28
l
Cable length:
450 m
Procedure
Cable length
See
1. Total cable length at 125 kbps:
630 m
2. Segment cable length for 28 bus nodes and a cable cross−section of
0.5 mm
2
:
360 m
3. Comparison: The value under point 2 is smaller than the required cable length of 450 m.
Conclusion
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It is not possible to use a cable length of 450 m without using a repeater.
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After 360 m (point 2) a repeater must be installed.
Result
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The Lenze repeater type 2176 is used (cable reduction: 30 m)
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Calculation of the maximum cable length:
First segment: 360 m
Second segment: 360 m (according to Tab. 5−1)
minus
30 m (cable reduction when a repeater is used)
à
Maximum possible cable length with repeater: 690 m.
à
Now it is possible to use the required cable length.
Note!
Repeaters are recommended as a
ƒ
Service interface
Advantage:
Trouble−free connecting during bus operation is possible.
ƒ
Calibration interface
Advantage:
Calibration/programming unit remains electrically isolated.