Daisy-chaining devicemaster up 2e/4-port units – Comtrol Modbus TCP Quick Start User Manual
Page 77
DeviceMaster UP EtherNet/IP Quick Start: 2000478 Rev. D
Troubleshooting and Technical Support - 77
Troubleshooting and Technical Support
Daisy-Chaining DeviceMaster UP 2E/4-Port Units
The DeviceMaster UP 2E/4-port models with external power supplies follow the IEEE specifications for
standard Ethernet topologies.
When using the UP and DOWN ports, the DeviceMaster UP 2E/4 is classified as a switch. When using the UP
port only, it is a simple end node device.
The maximum number of daisy-chained DeviceMaster UP 2E/4 units, and the maximum distance between
units is based on the Ethernet standards and will be determined by your own environment and the conformity
of your network to these standards.
Comtrol has tested with seven DeviceMaster UP 2E/4 units daisy-chained together using 10 foot CAT5 cables,
but this is not the theoretical limit. You may experience a performance hit on the devices at the end of the
chain, so it is recommended that you overload and test for performance in your environment. The OS and the
application may also limit the total number of ports that may be installed.
Following are some quick guidelines and URLs of additional information. Please note that standards and
URLs do change.
•
Ethernet 10BASE-T Rules
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The maximum number of repeater hops is four.
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You can use Category 3 or 5 twisted-pair 10BASE-T cables.
-
The maximum length of each cable is 100m (328ft).
Note: Category 3 or 5 twisted pair cables look the same as telephone cables but they are not the same.
The network will not work if telephone cables are used to connect the equipment.
•
Fast Ethernet 100BASE-TX rules
-
The maximum number of repeater hops is two (for a Class II hub). A Class II hub can be connected
directly to one other Class II Fast Ethernet hub. A Class I hub cannot be connected directly to another
Fast Ethernet hub.
-
You must use Category 5 twisted-pair 100BASE-TX cables.
-
The maximum length of each twisted-pair cable is 100m (328ft).
-
The total length of twisted-pair cabling (across directly connected hubs) must not exceed 205m (672ft).
Note: Category 5 twisted pair cables look the same as telephone cables but they are not the same. The
network will not work if telephone cables are used to connect the equipment.
•
IEEE 802.3 specification: A network using repeaters between communicating stations (PCs) is subject to
the “5-4-3” rule of repeater placement on the network:
-
Five segments connected on the network.
-
Four repeaters.
-
Three segments of the 5 segments can have stations connected. The other two segments must be inter-
repeater link segments with no stations connected.
for more specific information.
Additional information may be found
by
searching the web.