Epson RC620 Manual page 27

Drop Line Length
Drop line length is the distance from a branch on the trunk line to the end of that branch.
Node 1
In the figure above, each drop line length is as follows:
Drop Line to Node 1: 4 m
Drop Line to Node 2: 6 m
Drop Line to Node 3: 6 m
One drop line length should be 6m or less.
Total Drop Line Length
Total drop line length is the total distance of all drop lines in one network.
Terminating
Resistor
In the figure above, the total drop line length is 17 m.
The maximum total drop line length is restricted by baud rate as shown in the table below.
The cable thickness is not related to the restriction.
Cable Current Capacity
Current-carrying capacity of the DeviceNet network cable is restricted as below:
Current Capacity
Following figures illustrate examples of power supply configuration.
When an external power supply is installed in the network as shown in the figure below,
the current capacity is 11A and it exceeds the permissible current of the cable.
Terminating
Resistor
External Power
Supply 24 V DC
RC620 Option Fieldbus I/O Rev.8
Trunk Line
2 m
1 m
4 m
1 m 3 m
Node 3
Node 2
2 m
2 m
1 m
4 m
3 m
1 m
Baud Rate
500 kbps
250 kbps
125 kbps
Thick Cable
8A
Power Supply Tap
1A
1A 1A
Trunk Line
4 m
Max. Total Drop Line Length
39 m
78 m
156 m
Trunk Line
Thin Cable
3A
Trunk Line
2A 2A
2A
2. Installation
Terminating
Resistor
Drop Line (Unit: A)
4.57 / Drop Line Length (m) ≤ 3A
Terminating
Resistor
2A
17