Main types of cable:
Round
- Thick
- Mid
- Thin
Each variety can be used as a trunk or drop line. The smaller a variety is, the smaller its bend radius can be. This allows the cable to fit in more complex places. Smaller round line can limit throughput, though.
Flat
- Unshielded Drop
Flat cable is the recommended cable for a DeviceNet trunk line. It is comprised of a line of wires rather than a bundle. The insulating plastic is also formed to fit specific connectors, making flat cable a great solution for a fully compatible network with fewer custom components.
Unshielded drop cable is not actually flat cable, but is made to work with flat cable specifically. Unshielded drop cable is made solely for drop lines and is made up of 4 unshielded conductors.
Maximum Trunk Line Length:
- Distance between two furthest points.
- May not be the actual trunk line length.
- Maximum allowable length is determined by data rate and cable.
To determine the network’s maximum trunk line length, you must measure the distance between the two furthest points. If the distance from the terminating resistor to the last drop line on one side is greater than the length of the last drop line, measure to the terminal resistor. If the distance between terminal resistor and drop line is less than the drop line itself, measure to the device at the end of the drop line. This comparison must be made at both ends of the trunk line.
