3-2
Section
Limitations on the Network Configuration
26
3-2-4 Total Drop Line Length
This is the total sum length of all the drop lines. Even when the length of each
individual drop line is 6 m or less, be sure not to exceed the maximum total drop
line length. The maximum total drop line length varies with the baud rate as
shown in the following table.
Baud rate
Total drop line length
500 kbps
39 m max.
250 kbps
78 m max.
125 kbps
156 m max.
Configuration Example
Terminating
Resistor
Node
Node
2 m
Node
1 m
Node
2 m
Node
Node
Terminating
Resistor
2 m
3 m
Node
Node
6 m
2 m
2 m
1 m
1 m
Node
Node
Node
6 m
6 m
6 m
In the configuration example, the length of each drop line is 6 m or less as de-
manded but the total sum length of all the drop lines is 40 m. Set the baud rate at
250 kbps or 125 kbps because the total maximum length of drop lines at
500 kbps must not exceed 39 m.
3-2-5 Locating Terminating Resistors
Be sure to connect the Terminating Resistors at both ends of the trunk line to
reduce signal reflection and stabilize communications.
When there is a T-branch Tap 6 meters or less from the end of the trunk line (or
the node):
A Terminating Resistor attached to a T-branch Tap can easily be mounted
without taking up much space.
When there is not a T-branch Tap 6 meters or less from the end of the trunk line
(or the node):
A Terminating Resistor must be connected before that point. Either a T-
branch Tap mounted to a Terminating Resistor or a Terminating-block Termi-
nating Resistor can be used. In this case, be sure to make the cable length
1 m or less from the node to the Terminating Resistor.
Node at end of trunk line
Truck line
Node
T-branch Tap mounted to a Terminating Resistor
or a Terminating-block Terminating Resistor