Airwire consisting

Overview

This is not intended to be negative, but newcomers to the hobby and DCC don't always understand the nuances of the various types of consisting and their impact to operation / what you can do.

Again, DCC was designed as s system, where a central controller "knows" all the users and locomotives on the layout. Conflict is basically impossible.

Also, there are severe limitations in this system as compared to a "real" DCC system, and I do wish to point this out since many people do not realize this and later find out much to their chagrin.

The bottom line is to remember that AirWire is NOT a "DCC system", in fact it is neither true DCC (according to the NMRA definition) and it is NOT a system, i.e. where all the components work together.

To try to make sure there is no misunderstanding, one throttle and loco have no idea what another loco or throttle is doing. There is no "central intelligence" or control that is necessary in a system. So things like a universal stop all locos command, or shared knowledge of consisted locos, or the ability to control the "taking control" of a locomotive from one throttle to another are impossible.

This system is best suited to a situation where throttles and locos are not shared, i.e. where the operator stays with "his" locomotive, or if it is to be handed off, the throttle is physically passed to the new owner. Consisting of trains is severely limited, and there are many occasions where locos must have their radio frequency changed. The limited number of frequencies also limits the number of throttles, users, and locomotives in operation.

Consisting basics

One of the most often asked questions is about consisting.

Though 99% of you just say "give me the answer", in DCC systems, it's important to know about the 3 different ways to create a consist. Here are tthe definitions of the 3 kinds of consisting: (assume we have a consist of F units, "X" "Y" "Z" where "X" and "Z" are "A" units on the ends, "Y" is a "B" unit. Note that "Z" is running backwards. This simple example exercises the capability of the system, and points out advantages and weaknesses in the chosen system implementation

1. Basic consisting
All the locos in the consist have the same address, sending commands to loco "X" sends it to "Y" and "Z" too. Notice right off that for our example you have an immediate problem, you cannot run loco "Z" backwards without re-defining "forwards" in that loco. Also notice that honking the horn will honk on all 3 units, and the headlights in loco "Y" are on all the time.

2. universal consisting
The "system" is told which locos are in the consist, and in advanced systems, which direction the loco is facing, and what location in the consist the loco occupies. Depending on the level of support of the system this can be really effective. The downside is that you cannot take a consist to another layout and have it work (usually not a big deal) and the system sends separate commands to every loco every time, which on large systems could be an issue (like a club layout). Again this is not normally an issue in G scale.

3. advanced consisting
This gives the locomotives are given an additional address, a "consist address" (this feature is in the decoder itself) and all locos will respond to this address/single command from the throttle, basically you have a "common address" for all locos, like in #1 but you do not have to reprogram the locos to take them in and out of the consist. There are also sophisticated features regarding what functions get sent to which locos, so it is easy to have the consist itself have only the horn and bell come from the lead loco, and headlights out in the "center" locos. Also there is no limit to the number of locos in the consist. In addition, since the definition of the consist resides within the locos themselves, you can take the consist to ANY DCC layout.

Basically the advantages in terms of speed, capability, etc. increase from 1 to 3.

In Airwire, #1 is accomplished by reprogramming the address for each loco. This is a pretty lousy way to do this, even if you always run these locos as a consist... the headlights of all locos will be on in forwards, not just the lead loco. Likewise the horn and whistle will come from all locos. Yes, you can reprogram all the locos so that the lights work properly, and you can silence the other loco bell and whistle, but still will be wrong in reverse. This is the method used 20 years ago when there was no alternative.

In Airwire, method #2 is available, where the throttle sends commands for every loco in the consist are sent out every time. Depending on the throttle, you have up to 4 locos in each consist, and up to 4 consists. Unfortunately, as the consist grows, the overhead of sending the same command to multiple locos gets to be a problem. AirWire has addressed this issue by only allowing a maximum of 4 consists with a maximum of 4 locos each. (the original limit was ONE consist). This feature is back in the dark ages of DCC. To make it worse, all locos need to be on the same frequency.

Even though the AirWire system can program CVs you could program the consist address, I believe that the addressing/control for an advanced consist is different than a short address packet, so I do not think that method #3 is available with AirWire, if anyone know about it, let me know. To be clear, it should be possible to set up the addresses for advanced consists in the CV's in the locos, but I don't know if the consist address could be transmitted, I believe it is a different command than the normal loco address.