Advanced Consist lighting control when using NCE Advanced Consisting with TCS decoders.
Definition of Advanced consisting: Advanced consisting is the use of CV19, CV21, and CV22 to control motor and light functions when locomotives are run together in multiple unit lash ups. If advanced consisting is not used then the command station uses the base address of all the units in the consist to send the speed and lighting information to each unit in the consist. Some modelers are puzzled how to get full control of all light functions in all the units making up an advanced consist. In particular the question is this. When running a consist forward how do you get the lead locomotive headlight to be on and the rear light off while on the trailing locomotive the lights are off. And visa verse when running in reverse direction. The solution to set up for expected directional control of lights in an advanced consist is to manually program CV19, CV21, and CV22 and send commands to the consist address as if it were a regular locomotive. If you do it in this way you will maintain the benefits and versatility of advanced consisting. You will be able to have proper directional control the lead locomotive headlight and rear locomotive light. For more explanation as to why to do this manually continue reading. How is this supposed to be done according to NMRA recommended practices ? From NMRA Recommended practices RP 9.2.1 page 4 of 10. paragraphs 155, 160, 165: Functions 0-12 will continue to respond to the decoders baseline address. Functions 0-12 also respond to the consist address if the appropriate bits in CVs #21, 22 have been activated. (edited slightly for the purpose of being understandable) BEFORE performing any programing, make sure you turn all the lights on the engine off. We believe that there are two ways of interpreting the use of the word also in the above statement from the NMRA recommended practice (RP9.2.1) NCE seems to be conforming to the second interpretation, listed below while we subscribe to the first interpretation. Two interpretations: 1) (TCS interpretation) F0-12 will continue to respond to the decoders base address even though the motor responds to consist address. If the appropriate bits are set in CVs #21, 22 then F0-12 will respond to the consist address and no longer respond to the base address. (The also in the RP9.2.1 statement would refer to the previous paragraph regarding motor control. ie. The lights will now also respond to the consist address even as the motor does.)
2) (NCE interpretation) F0-12 will continue to respond to the decoders base address. If the proper bits are set in CVs #21, 22 then F0-12 will respond to the consist address as well as to the base address.
Advanced Consisting Explained further explained. Consisting is when more than one locomotive is coupled together to run a train. When doing this, one would want all locomotives in the consist (in that train) to be running on the same DCC address. Historically there were two ways of doing this, by either programming all of the locomotives in the consist to the same address using CV1, which required individually moving each locomotive to the programming track and programming its address, or by doing Universal consisting. Universal consisting was done by the command station and simply sent out commands to the locomotive addresses of each locomotive in the consist. (For example, if locomotive 3, 4, and 5 were in a consist that had was assigned the address of 10. When you send commands to address 10 the command station will relay those commands to addresses 3, 4, and 5.) The problem with this method of consisting was that it limited the versatility of functions for each locomotive in the consist. Lighting commands were only sent to the lead unit, which was better than when every locomotive had the same address so all of them had the same lighting commands, but Universal consisting still didn't give full control of each locomotive in the consist. Then along came advanced consisting. Someone came up with the brilliant idea that the decoder could have another address CV that would not clear its base address (CV 1) and would be programmable on the main track. This CV became CV 19. So consisting took on a whole new twist, because you could simply program the consist address to CV 19 on the main and never worry about losing the base address of the locomotive, so that when you wanted to break the consist you could simply program a value of 0 back into CV 19 and the locomotive would be exactly as it started. The next question, however, was what to do about the lights. If the lights were controlled by the consist address, then every unit in the consist would have its lights on all the time, which is not realistic. So originally the speed and direction commands were sent to the CV 19 address and lighting commands were sent to the CV 1 address. This was tedious, so two more new CVs were employed. It was decided that CV 21 and 22 would be used to select whether the lights were controlled by the consist address OR by the base address. Ok, time for an example.
If you have 2 locomotives in a consist, one with CV1 set to a value of 5 and the other with CV1 set to a value of 27, but you want the consist to run on address 12, you would program CV 19 in both locomotives to a value of 12 and now they will both respond to speed and direction commands together. (One other variable, if you want to run one of the locomotives in reverse in the consist, then you simply add a value of 128 to the address that you want and put that into CV19. In the previous example, if locomotive # 27 was supposed to be the trailing unit and it will be running in reverse, then it will receive a value of 140 in CV19 and will now respond to speed and direction commands from address 12, but it will run backwards from locomotive #5.) Now, lets say that locomotive 5 is the leading unit and locomotive 27 is the trailing unit, and they are both running forward in the consist. This means that the when the consist is running in forward you want the forward headlight of locomotive 5 turned on and no other lights on, when the locomotive is running in reverse you want the reverse light of locomotive 27 turned on and no other lights turned on in the consist. This is where CV 22 comes into play. If you program a value of 1 into CV22 it will make the forward headlight for that locomotive active on its consist address. If you program a value of 2 into CV22 it will make the reverse light for that locomotive active on its consist address. So, for this application you would program a value of 1 into CV22 for locomotive 5 (If programming in OPS mode you will still use the locomotive's base address for programming NOT its consist address.) Then you would program a value of 2 into CV22 for locomotive 27. This would give you the most forward light of the consist on in forward and the most rear light of the consist on in reverse. If, however, you wanted both forward lights on in forward, but only the most rear light on in reverse, you would program a value of 3 into CV22 for locomotive 27 (the value of 3 is simply 1 (forward light) + 2(reverse light) = 3(both forward and reverse light). Now the trailing unit's forward and reverse lights will be controlled by the consist address, and the lights will respond as desired. This is a rather long explanation, but advanced consisting is very easy to use once you have tried it. The nice thing is that you have full versatility with your lights and can do all of the programming on the main track.