Omron SmartController EX, Руководство пользователя

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Chapter 6: DeviceNet
NOTE: This hot-pluggable feature requires the configuration of the controller to
match the configuration of the physical network. The default configuration auto-
matically recognizes and maps the first 64 bits of Mac ID 1 and 2. If the con-
figuration needs to be changed, use ACE Configuration Tools.
The power distribution on the network / bus does not need to be in one place. The distribution
of power supplies needs to be well-planned because there are certain constraints on the power
supply. In general, power supplies can be placed at any point in the network. The maximum
current rating of a trunk line is 8 amps. DeviceNet allows opto-isolated, externally powered
devices (e.g., AC drive starters and solenoid valves) to operate on the same bus cable. For
detailed information, see the DeviceNet Technical Specifications.
Table 6-3. Features of a DeviceNet Network
Network Size A maximum of 64 nodes [0 - 63]
Network Length Selectable, end-to-end network distance varies with speed
Data Packets 0-8 bytes
Bus Topology Linear (trunk line / drop line); power and signal on the same network
cable
Bus Addressing Multi-Master and Master / Slave special case; polled
The baud rate of the system depends on the length of the network (end-to-end) and the type of
cable. The following table shows how cable selection and trunk line length affect the max-
imum data rate on the network. The figure DeviceNet Thick Cable on page 64 shows a thick
cable, and the figure DeviceNet Thin Cable on page 65 shows a thin cable.
Table 6-4. DeviceNet Data Rates Relative to Cable Type and Length
Data Rates 125 Kbps 250 Kbps 500 Kbps
Thick Trunk Length 500 m
(1,640 ft) 250 m
(820 ft) 100 m
(328 ft)
Thin Trunk Length 100 m
(328 ft) 100 m
(328 ft) 100 m
(328 ft)
Maximum Drop Length 6 m
(20 ft) 6 m
(20 ft) 6 m
(20 ft)
Cumulative Drop Length 156 m
(512 ft) 78 m
(256 ft) 39 m
(128 ft)
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