Bridge message passthrough

Hi

I have set up two bridges on a small test network and have set the connect application to "ALL APPLICATIONS" and checked the message destination to "adjacent networks" for all network bridges.
Messages transfer OK from the local to the adjoining network or from the last network to its adjoining network. However I have a problem in sending messages from the last network to the local network or from the local to the last network?

For some reason the messages are not transfered over the connecting bridges?

Any help would be most appreciated.

 

Can you please give a bit more information about your set-up? A drawing of how you've got things connected, the messages you're sending as well as the settings for the options in the PCI?

 

If I'm understanding you correctly, you've got 3 networks connected in a line, A - B - C, and you've got C-Bus devices on all 3 networks. All Applications is specified in Application 1 on all the Bridges and the Send to Adjacent Network flag checked. You're pressing buttons on the input units on network A and network B gets them but network C doesn't? Likewise, pressing buttons on the input units on network C get sent to network B but not back to network A?

For your configuration, this is the correct behaviour.

When C-Bus messages are sent across a bridge, the network routing information is included to specify the destination network and the path to get there. The network bridge will put this information into local network messages as they pass through. From that point onwards, the network routing history remains in the message so that the reverse path can be identified. When the message reaches the target network it stops and the relevant units do their stuff, but the reverse path is still in the message.

In your situation, the message from the unit on the local network is being seen by the A-B bridge, the network path to the adjacent network B is being inserted, and then it's flicked out the other side onto network B. When the message lands on network B, the BC bridge sees the message, but it ignores it because it already has network routing in it. As far as the B-C bridge is concerned, that message has reached it's destination and has no need to go any further.

The reason C-Bus works this way is to prevent race conditions from occurring on the network. If messages could be sent everywhere, and they looked the same a locally-generated messages, then they could be forwarded to another network, and another network, and another network... the potential for the whole system to go down as it clogs up with redundant messages is very real.

To solve this problem, you need to turn on the other Message Destination option in the Bridge UI for the local side of the A-B bridge. Check the box that says "Send to other remote network" and select network C. You need to also do the reverse in the B-C bridge, sending to other remote network A.

Note that these are the rules for messages that are generated locally on the network. Messages that are sent by a PC or a C-Touch-like device can be explicitly routed to any network in an installation, regardless of the configuration of the bridges.

For further reading, there is a C-Bus Networks Application Note on the CIS website that goes into some of this in more detail.

 

thanks Newman

Have now setup bridges as you say and your "spot on" !