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A very low error bit rate over CAN can only be achieved with a suitable wiring scheme, so the following points should be observed:
HThe
H The bus must be terminated at both ends only (not at intermediate | JP1 |
points) with resistors of a nominal value of 120Ω. This is to reduce |
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reflections of the electrical signals on the bus, which helps a node to |
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interpret the bus voltage levels correctly. If the NextMove ES is at the |
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end of the network then ensure that jumper JP1, located just behind |
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the status display, is in position. This will connect an internal |
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terminating resistor. |
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HAll cables and connectors should have a nominal impedance of 120Ω. Cables should have a length related resistance of 70mΩ/m and a
nominal line delay of 5ns/m. A range of suitable CAN cables are available from Baldor, with catalog numbers beginning
HThe maximum bus length depends on the
(1)CAN baud rate not supported on Baldor CAN.
(2)For bus lengths greater than about 1000m, bridge or repeater devices may be needed.
CAN |
| Maximum |
| ||
Baud Rate |
| Bus Length |
|
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|
1Mbit/s |
| 25m |
500Kbit/s |
| 100m |
250Kbit/s |
| 250m |
125Kbit/s |
| 500m |
100Kbit/s (1) |
| 600m |
50Kbit/s |
| 1000m |
20Kbit/s |
| 2500m(2) |
10Kbit/s |
| 5000m(2) |
|
HThe compromise between bus length and CAN baud rate must be determined for each application. The CAN baud rate can be set using the BUSBAUD keyword. It is essential that all nodes on the network are configured to run at the same baud rate.
HThe wiring topology of a CAN network should be as close as possible to a single line/bus structure. However, stub lines are allowed provided they are kept to a minimum (<0.3m at 1Mbit/s).
HThe 0V connection of all of the nodes on the network must be tied together through the CAN cabling. This ensures that the CAN signal levels transmitted by NextMove ES or CAN peripheral devices are within the common mode range of the receiver circuitry of other nodes on the network.
On the NextMove ES, the CAN channel is
MN1928 | Input / Output |