Wiring
Operating instructions PMCprimo C
1002242-EN-03
30
6.6.2
CANopen, PROFIBUS DP
Depending on the unit type, socket X42 is assigned to
}
A combined CANopen/PROFIBUS DP interface
}
Two CANopen interfaces
6.6.2.1
Wiring guidelines for the CANopen interface
The CAN network is designed in a linear structure.
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The overall line length and the length of the stub lines depend on the transmission rate
and on the cable properties (cable resistance and cable capacitance).
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The signal lines must be terminated with resistors on the first and last subscriber.
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A characteristic impedance of 120 Ohm is acceptable for bus lengths up to 40 m.
Node 1
Node 2
Node n-1
Node n
RT [
W
]
l
a
Node 3
A
A
RT [
W
]
Fig.: Overall length and length of the stub lines on a CAN network.
Legend:
}
Node: CANopen subscriber
}
a: Length of stub line
}
A: Branch
}
R
T
: Terminating resistor
Relationship between transmission rate, bus length and length of stub lines:
Transmission rate
[kBit/s]
Bus length l [m]
Length of stub line
a [m]
Overall length of all
stub lines [m]
1000
10
1.5
7.5
500
70
5.5
27.5
250
115
11
55
The following table provides an approximate overview of the size of the terminating resistor
R
T
with different cable lengths. In each specific case, details of the characteristic imped-
ance can be found in the cable specification.