Your Source for RV-C Information.

There are just two steps to designing an RV-C compliant RV. First, the coach must be properly wired. And second, the components must be checked, and if necessary properly configured, for proper interoperation. The following section will consider those “software” issues. This section will describe the wiring required.

RV-C wiring is an example of a “bus topology”. The jargon simply means that RV-C uses one of the simplest possible methods of connecting multiple nodes. A “trunk” line is run through the RV, terminated on each end by a small (120 Ohm) resistor across the pair. Wherever necessary, “drops” are made using the same kind of cable to each node. The cable itself is a twisted pair, and the drop meets the trunk in an simple tee. The “high” line is connected to the “high” line, and the “low” to the “low”.

The bus topology offers several advantages over alternatives like “star” and “daisy chain” systems. Unplugging any node has no effect on the rest of the network. Troubleshooting the wiring is easy with ordinary tools – the “high” line at each node should have continuity with the “high” line at every other node, and the same is true for the “low” line. The resistance between the high and low lines should read sixty ohms.

There are a few limitations on the length and type of wiring. The RV-C specification allows for a variety of wire types, but for a variety of reasons SilverLeaf recommends using Raychem 2019E0309, a 20 gage cable that will support a total network length of over 250 meters.

Regardless of the cable chosen, the drops are limited to no more than six feet in length. Thus the trunk must be routed fairly near every RV-C component. Putting two components on the same drop is also prohibited.

There is no standard connector for RV-C components. However, one item that is standardized is the diagnostic port. This is a drop to a connector located in or near the service bay of the RV. It is used by service technicians, who will plug their laptop service tools into it to get diagnostic and configuration information. The plug is a nine-pin connector from the Amp Circular Plastic Connector Series. (The typical part number is 206705-1, but variants are available to allow different mounting methods.) A dust cap should be placed on this connector when not in use.