One of the advantages of of the MERGER DMX is the available backup mode, which can be edited via dip-switches. Many users ignore this function but it is very useful: it allows sending DMX frame even if there is a failure in the main line.
The signal that comes from the console goes to a DMX splitter which double the signal and send it to the two inputs of MERGER DMX. When the backup mode is activated, the signal of the A input directly goes to the DMX output. In the meanwhile, the signal of the B input is in standby mode (see part 1 of the diagram).
If the signal is lost in the A input line, the B input is automatically activated to ensure that the show goes on (see part 2 of the diagram).