Daisy-Chaining Devicemaster 4-Port Units - Comtrol DeviceMaster MOD Series Hardware Installation And Configuration Manual

Troubleshooting and Technical Support

Daisy-Chaining DeviceMaster 4-Port Units

88 - Troubleshooting and Technical Support
The DeviceMaster 4-port (panel mount) models with external power supplies
follow the IEEE specifications for standard Ethernet 10/100BASE-TX topologies.
Note: If the serial number of your product is above xxxx-030000, the UP and
DOWN Ethernet ports are interchangeable.
When using the UP and DOWN ports, the DeviceMaster 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 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 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. Note
that standards and URLs do occasionally change.
• Ethernet 10BASE-T Rules
- The maximum number of repeater hops is four.
- 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.
Additional information may be found by searching the web.
DeviceMaster MOD | UP Hardware Installation and Configuration Guide: 2000630 Rev. B