User`s manual

Western Reserve Controls WRC-CANR-DF-DN User’s Manual

PUB 14.1

5. Operation

CANR-DF receives and stores messages received at either network connection and actively re-

transmits the message while providing 2500V isolation between the two sections of the nework. The two bus

connections for each CANR-DF are referred to as Network A (copper wire), and Network B (fiber optic

cable), but they are the same logical network with isolation between them. To extend the maximum

distance that a network.

This inclusion of the fiber network section into your CAN-Bus system requires that the the CANR-

DF units be used in pairs. And each pair consist of one Type 1 CANR-DF and one Type 2.

The CAN Bus is connected to the A Side of the CANR-DF and receives its power from the Bus.

Whenever a message is transmitted on the Bus to which the CANR-DF pair is connected, one

CANR-DF receives the message on the side where it was initiated and performs a store-and-forward of the

message to the other side. This action is performed for any valid CAN message independent of who

generated it or to whom it is intended.

There is approximately a 75 µsec propagation delay of the message through the CANR-DF.

The CANR-DF is not addressed as a specific device on the Bus and cannot be interrogated by other

nodes. It is transparent to all other nodes on the bus.

5.1. Application Notes

NOTE: CANR-DF’S ARE ALWAYS USED IN PAIRS!

To help insure ease of installation and reliable operation of your system, the following guidelines

should be followed CANR-DF installation in your CAN network.

1. Make sure the pair consists of a Type 1 and a Type 2.

2. For Autobaud versions, the baud rate each device selects will be defined by the first valid

message received from either the CAN-Bus or via the fiber connection from the other device.

3. Use only one CANR-DF pair in any network section. That is, only use one CANR-DF pair per

trunk line or drop line.

4. CANR-DF is not a grounded device and the Bus shield is not connected electrically to the

device. Therefore, follow appropriate wiring practices to eliminate noise and other problems.

Examples of valid configurations are shown in the following figures.

Figure 5-1 CANR-DF on a drop line