Electrical installation
Wiring of system bus (CAN)
5
94
EDBCSXA064 EN 3.2
Example: Selection help
Specifications
l Cable cross−section: 0.5 mm
2
(according to cable specifications 91)
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
l Cable cross−section: 0.5 mm
2
l Number of nodes: 28
l Cable length: 450 m
Procedure Cable length See
1. Total cable length at 125 kbps: 630 m Tab. 5−1
2. Segment cable length for 28 bus nodes and a cable cross−section of
0.5 mm
2
:
360 m Tab. 5−2
3. Comparison: The value under point 2 is smaller than the required cable length of 450 m.
Conclusion
l It is not possible to use a cable length of 450 m without using a repeater.
l After 360 m (point 2) a repeater must be installed.
Result
l The Lenze repeater type 2176 is used (cable reduction: 30 m)
l 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.