Salut Jean-Paul,
j'aurais dû dire "risque" au lieu de "va" puisqu'on n'est pas obligé de mettre une adresse.
Que des centrales et softs le permettent, c'est une chose. Mais c'est risqué:
Je te laisse lire la norme NMRA qui explique pourquoi:
https://www.nmra.org/sites/default/files/standards/sandrp/pdf/S-9.2.3_2012_07.pdfUn résumé intéressant:
Operations Mode - Addressed commands that go to a one specific loco. Normal operations commands control functions such as throttle, lights, horn, etc. Operations Mode programming (aka POM) must also be an addressed command to change the value of CVs. The decoder must support ops mode programming. The intent was to allow for changing things that make sense to change when the loco is on the main track like sound profiles, speed tables, speed matching, momentum, etc. It would be tedious to adjust motor settings by putting them on PROG, changing them, moving them to MAIN, testing it, and then repeating the process. Instead, the loco could be on the track, other locos could also be on the same track, and you can adjust your settings via blind writes to CV locations and see the results of the change in real time. There is no acknowledgement from the decoder, therefore there is no way to read CVs. When an addressed command is received by a decoder, it bypasses its internal ACK mechanism. Since the loco could be in motion, and the ack pulse is usually created by sending a current pulse to the motor when it is idle, this would make no sense. In addition multiple locos and any number of accessory decoders and things that affect current could also be on the track.
Service Mode (AKA Program Mode) - Broadcast commands that are received by any decoder on that track and should be sent ONLY to an isolated track separate from the main (ops) track. This mode is designed primarily to program ONE decoder at a time, though you could set CVs for all decoders to a specific value with the understanding that you can't use an ACK to sense if the value was written correctly. Some software will fail because it is written to look for the ack. But even in the absence of the acknowledgement, the CV value will still be changed. However, service mode on an isolated piece of track is the only specified method for reading CVs and the proper place for changing most CV settings such as the loco address, CV29, etc. Changing the address of a loco to which you are sending an addressed command to that very address, also makes no sense.