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ID : 5550
System Configuration and Configurators
This section describes the network system configuration and configurators in DeviceNet.
System Configuration Sample
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Nodes
A DeviceNet network has two kinds of nodes: slaves to which external I/Os are connected, and a master that controls these slaves. Note that their addresses are just network settings, so the master and slaves can be freely arranged on physical sites.
- Up to 63 slaves can be connected.
Trunk Lines and Drop Lines
The trunk line is a cable whose both ends are terminated with resistors. A drop line is a cable that branches off the trunk line. The trunk line and drop lines can be constructed using DeviceNet thick cables, DeviceNet thin cables, or both.
- Thick cables are used for long-distance trunk lines, strong trunk lines, and drop lines.
- Thin cables are used for trunk lines and drop lines, and for easy termination processing.
Trunk Line Length
The permissible total length of a trunk line used in a DeviceNet network will differ depending upon the data transmission speed and the type of cables used (thick cable or thin cable).
Communications speed |
Maximum cable length |
Maximum cable length |
|---|---|---|
125 Kbps |
500 m |
100 m |
250 Kbps |
250 m |
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500 Kbps |
100 m |
A DeviceNet network may be constructed with thick and thin cables together. In such a case, the permissible total lengths of thin and thick cables can be obtained according to the calculation formulae below.
“L (thick)” indicates the length of thick cables.
“L (thin)” indicates the length of thin cables.
Communications speed |
Maximum network length |
|---|---|
125 Kbps |
L (thick) + 5 * L (thin) ≤ 500 m |
250 Kbps |
L (thick) + 2.5 * L (thin) ≤ 250 m |
500 Kbps |
L (thick) + L (thin) ≤ 100 m |
Drop Line Length
The drop line length is cable distance between the trunk line tap and the farthest node on the drop line. The permissible overall length of drop lines throughout the network ("total length") depends on the communications speed, and must be within the lengths listed in the table below.
Communications speed |
Drop line length |
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|---|---|---|
Maximum length |
Overall length |
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125 Kbps |
6 m |
156 m |
250 Kbps |
78 m |
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500 Kbps |
39 m |
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Terminating Resistors
Terminating resistors must be connected at both ends of the trunk line in a DeviceNet system. The specifications of the terminating resistors are listed below.
- 121Ω
- Metal film resistor with resistance error of less than 1%
- 1/4W
Never connect a terminating resistor to a node. This may result in a failure.
Communication Power Supply
To operate a DeviceNet network, a communication power must be supplied to each node through DeviceNet cables. The communication power supply, internal circuit power supply, and I/O power supply should be supplied separately.
DeviceNet Connection Style
As shown below, a variety of connection styles are available for DeviceNet. They include multidrop, star connection, T-ports, daisy chain, and drop line branching.
DeviceNet connection style
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ID : 5550