The DL251 has 3 x AES50 Ports labelled 1, 2 and 3. As standard, on power up, if all three connections are made;
- Port 1 normally transmits the master clock, control data, and digital audio for input channels 1 - 24 and output channels 1 - 16
- Port 2 normally transmits control data and digital audio for input channels 25 - 48
- Port 3 is normally the redundant
If during operation, either Port 1 or Port 2 were to drop, then the redundant Port 3 would immediately take over this role. The only exception to this would be if one of the pins on the RJ45 was bent and bouncing (due to vibration). In this case, the Port would come back up so quickly that the redundant would not have time to take over. Normally, this would not be noticed due to the forward error correction of the system. If the pin were to be disconnected for long enough, then the redundant would start to take over. However, if the original Port came back up again before the redundant had fully taken over, then it would recover its role and the redundant would drop. A very small loss of audio would be heard on those particular channels
If the following scenario arose that the redundant is already being used, and then Port 1 (for example) were to fail, the other active Port would take over the role of Port 1 and input channels 1 - 24 and outputs 1 - 16 would still be operational. Port 1 would always be the last active Port.