Eaton Cutler Hammer MN05001002E Installation Manual

Intelligent Technologies QCPort System Install ManualNovember 2005MN05001002E For more information visit www.eatonelectrical.com Page 14Planning a QCPort TopologyQCPort is a RS485 based system and allows only two topologies; they are daisy chainand trunk drop. Connecting QCPort in a star is not allowed since it will produceunreliable communication.Daisy ChainA daisy chain topology consists of a single wire that connects devices. This single wireenters and exits the device at one point (two connectors). Devices that can be connectedin this topology have two QCPort connectors on them and/or a QCPort backplaneconnector. The two QCPort connectors are in parallel with each other so the connectionis virtually one wire between devices.When designing a system using daisy chain, there are two rules to be aware of. First, thecomplete QCPort system cannot be greater than 100 feet [30 meters], and second, thelongest wire distance between devices, using the pre-manufactured QCPort InterconnectCables, is 10 feet [3 meters]. When distances longer than 10 feet [3 meters] are requiredbetween devices, there are other methods that include using a long run cable andconnectors.Methods of connection include using QCPort Interconnect Cable, QCPort Backplane,Long Run, or any combination of the three. For more information on connectionmethods, see “Device Connection in a QCPort System on page 11.Figure 9: Daisy Chain TopologyTrunk DropA trunk drop topology consists of a single wire, the trunk, with multiple drops coming offthe trunk. The trunk can be the Backplane or long run cable where the drops are thenconnected to the trunk. When the trunk is a Backplane, the drops will connect usingQCPort Interconnect cables from the devices on the Backplane. When the trunk is a longrun cable, a D77E-QPLR (biasing resistor and power tap) is used to change the long runinto either a Backplane or QCPort Interconnect cable connection. The biasing resistorportion of the D77E-QPLR is capable of being switched on or off. When used as a droppoint in a long run cable application, the biasing resistor will most likely be switched off.The rules to be aware of when designing a Trunk Drop system are that the maximumdrop cannot exceed 1 foot [0.3 meter], and that the sum of the drops cannot exceed 20feet [6 meters].