West Control Solutions KS 800 CANopen Interface Manual User Manual
Page 44
KS 800 CAN-Interface
11.2
Bit rates and bus lengths:
The maximum useful bus length in a CAN network is determined by a variety of physical effects,
in particular:
The delay time of the connected bus nodes (with/without opto-couplers) and the delay
time of the bus cable (propagation delays),
various scanning times within a CAN bit cell due to the oscillator tolerances of bus nodes,
signal amplitude attenuation due to the DC resistance of the bus cable and the input
resistances of bus nodes.
When using ISO 11898-2-compliant transceivers, the bus mentioned below can be reached with
standard bus cables.
Nevertheless, the bus lengths may be considerably shorter with the high bit rates
(1 Mbit / 800 kbit) due to the number/speed of any opto-couplers (galvanic isolation)!
11.3
Practical bus lengths
CAN-Profil(s)
Baud-rate
Bus-length
Nominal
Bit-Time
CANopen
1 MBd
30 m
1
µ
s
CANopen
800 kBd
50 m
1,25
µ
s
CANopen/DeviceNet
500 kBd
100 m
2
µ
s
CANopen/DeviceNet
250 kBd
200 m
4
µ
s
CANopen/DeviceNet
125 kBd
500 m
8
µ
s
CANopen
50 kBd
1000 m
*
)
20
µ
s
CANopen
20 kBd
2500 m
*
)
50
µ
s
CANopen
10 kBd
5000 m
*
)
100
µ
s
*
) With very long cables, using galvanic isolation and repeaters is indispensable.
For further information on bus lengths, see also standards CiA _DS-102_ (CANopen) or ODVA
_DeviceNet Specifications Volume I, Release 2.0_, in particular, Appendix A and B.
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