LCC, For Real

Well, it didn’t take long. The first useful commercial products based on the LCC standards are out, and I have a set. While I may have some reservations about the state of the standards themselves (see my earlier series of posts), I’m very excited to see real products, and at fairly reasonable prices. Well, somewhat reasonable; I’ll have some comments on that.

New Plans for a New Year

I'm going to usher in the new year with a new project, and try to get back to doing more frequent but smaller posts than I've done of late. I'm not quite back to railroading yet, although this is ultimately in support of that. But for the moment, I'm still playing with microelectronics. And today's post is just a summary of where I'm going and what I've done so far, which doesn't amount to much when you put it down in words.

I'm still thinking about and planning the next layout. Control systems are a big part of that, because I was never happy with the DCC-throttle control of turnouts I used on Sumida Crossing, and my attempt at a single big computer-driven system never got off the ground, and would have had some of the same issues if it did.

As you may have noticed, I've spent a lot of time looking at control bus systems over the last two years. I'm still on the fence about what to use, as I don't particularly like any of the current systems. LCC has promise, but so far that's all it has, and I'm not expecting much from it in the next couple of years; it's too new.

LCC III - Messaging

Back in October I started what I thought would be a relatively easy, if perhaps a bit long, post on messaging in LCC. I was trying to cover it in detail, explaining how the ideal LCC had to be adapted on CAN Bus. That proved distracting and I put that material aside to just focus on the basic messaging capabilities of LCC rather than the implementation on CAN Bus, at least to the extent I could.

In the process of doing this, I've managed to chase myself in circles more than a few times. The LCC standards are very confusing, even by NMRA standards. We're talking about documents written by volunteers rather than professional standards-writers, and generally without a whole lot of editing. I've been reading NMRA standards for more than 25 years and I'm used to having to work at it to puzzle out the actual meaning. But still, the lack of clarity in the LCC documents is exceptional.

I'll detail problem areas throughout this post, but it basically boils down to things either being omitted entirely from the documents or being covered in one of the other technical notes than the one you’d expect. And there's a fair bit of using two different names for the same thing and, conversely, using similar names for two different things.

The revised post is about messaging in LCC and what you can do with it now, and additionally I'm coming at this as a review of the LCC standards, not anything external to them. The OpenLCB team has written a lot of words about OpenLCB, and that’s often helpful, but what matters in a standard is what's actually incorporated in it, either directly or by reference to or citation of an external document.


LCC II - How It Works - Physical

This is the second in a series of posts on the NMRA's new Layout Command Control (LCC) standards. The first post covered the reasons why a control bus, and specifically LCC, were important, as well as providing a fairly high-level view of how LCC works. Today we'll get into some very specific details regarding the physical aspects of the network, specifically the CAN Bus wiring and usage. Next time, I'll cover the actual messaging on the network (i.e., what you can do with it).

LCC I - Layout Command Control

Three years ago, in 2012, the NMRA published their first standard related to a layout control bus, at the time known as NMRAnet. This was standard S-9.7.1 NMRAnet: CAN Physical Layer, which defined the electrical characteristics of the bus (e.g., details of the wire, connectors, bit rate, and voltage levels). Several companies were producing useful circuit boards based on the standard, although their functioning depended on capabilities not adopted at that time.

This standard, and the not-yet-adopted parts used to make the first implementations, were based on something called OpenLCB, which stands for Open Local Control Bus (not "Layout Control Bus"). Open LCB was one of several competing proposals for NMRAnet. The OpenLCB team demonstrated how this would work at the 2010 NMRA convention, and has a page of videos and other information from then. Over the subsequent two years it came out on top as the solution of choice. However, some of the potential demonstrated there does not seem to be fully fleshed-out in even the current standards. We're not done with the development of LCC by any means.

But we have had significant progress this year. Back in February the NMRA adopted 21 additional documents, 10 more Standards and 11 clarifying Technical Notes. They also renumbered them slightly, and changed the name to Layout Command Control, or LCC. These were formally adopted with a six-month comment period that ended on September first. Updates based on those comments are still possible, so the standards aren't quite done yet, but they're probably very close to their final form.