Emerson SI-DeviceNet, Руководство пользователя

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SI-DeviceNet User Guide
15
Issue Number: 2
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4.6 DeviceNet ground point
The DeviceNet cable shield must be grounded AT ONE POINT only, usually near the
centre point of the cable run. This is to prevent the cable shield from becoming live in
the event of catastrophic failure of another device on the DeviceNet network.
4.7 Maximum network length
The maximum number of nodes that can be connected to a single DeviceNet network
segment is 64. The maximum length of network cable for a DeviceNet network is
specified by the
Open DeviceNet Vendors Association and depends on the data rate to
be used.
4.8 Spurs
Control Techniques do not recommend the use of spurs on a DeviceNet network.
4.9 Minimum node to node cable length
The DeviceNet specification does not specify a minimum node to node distance,
however, Control Techniques advises a minimum distance of 1 m between nodes to
prevent excessive bend radii and to reduce network reflections.
Table 4.3 DeviceNet maximum segment lengths
Data rate (bits/sec) Maximum network length (m)
1 M 30
800 k 50
500 k 100
250 k 250
125 k 500
100 k 700
50 k 1000
20 k 2500
10 k 5000