10Mbit Hub Example

Ethernet design rules apply for the maximum distance between workstation A and workstation B (the furthest points) when four repeaters are in series that are connected by twisted pair link segments for the 10Mbit networks shown in Figure G-58. Each port on each hub can have a 100 meter (328 feet) maximum length twisted pair cable attached. This allows a total network diameter of 500 meters (1640.5 feet) end to end. This configuration can be implemented at installations having several wiring closets or rack rooms configured within a single building with stable environmental conditions and a common ground.

The 3Com mini-hubs in Figure: 10Mbit Copper with 8 Port Hub have the following specifications:

8 port non-stackable
table top or wall mount
external wall plug power supply
no upgrade options for Fiber-Optic Transceivers

Note

Make a ground connection to the mini-hub chassis with a 12 AWG wire for the twisted pair cable shield ground.

In the following figure any port on any hub can be used for DeltaV Workstation, Controller, and Application Station connections. However, port 8 on each hub is a special port used for the hub to hub connections. The hub to hub connection through these special ports allows the use of a standard straight-through twisted pair cable. A push button next to these ports is for the crossover function. When the crossover function is not used, the port can be used for regular workstation and controller connections.

Figure: 10Mbit Copper with 8 Port Hub

Callout	Description
	100 m (max) straight-through cable. To prevent ground loops, build this cable assembly with a shielded, metal-enclosed RJ45 connector on one end and an isolated, plastic-enclosed RJ45 connector on the other end. The metal connector end of this cable assembly/link can be placed on either hub.
	100 m (max) straight-through cable. The shield on the controller's RJ45 connector connects only to a Faraday cage in the controller; not to the controller's DC ground. Therefore, the RJ45 connectors are floating and the single point of ground is made at the hub or switch to which the controller is connected. Build this cable assembly with a shielded, metal-enclosed RJ45 connector on both ends .
	100 m (max) straight-through cable. To prevent ground loops, build this cable assembly with a shielded, metal-enclosed RJ45 connector on one end and an isolated, plastic-enclosed RJ45 connector on the other end. The metal connector end of this cable assembly/link must be placed on the switch and hub but not on the PC.