LocoNet
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.
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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.
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Occupancy Detection Yet Again
About fifteen months ago work on adding occupancy detection to Sumida Crossing stalled. That was in part because I’d planned to use the BDL168 detectors to also do transponding, and a few months earlier had abandoned that plan since I was unable to get that aspect to work reliably, even on a simple test track. The number of solder joints on the BDL was also a nuisance that caused me to put off further work.
Recently I’ve been rethinking my approach. The BDL168 is an amazingly cost-effective solution. Ignoring the transponding part, you get 16 detectors on a board that includes a LocoNet bus interface for US$120 (street price). That’s $7.50 per detector (if you can use all 16). That’s really hard to beat for a bus-connected detector. I’d originally planned to install one per table on the layout, and my cost would have worked out to around $10 to $15 per detector on average.
On the other hand, I’m thinking that I might want to move to either a OpenLCB/NMRAnet bus (if I want a feature-rich bus for the future) or a really dumb serial bus (like S88 or C/MRI). The latter is attractive since I can potentially interface to it with an Arduino, opening up some room for home-brew devices. Of course I could do that with NMRAnet, but today that requires a US$45 shield to add to the Arduino (or one with it built in), which kind of takes away from the appeal of using $10 Arduinos to do things like drive signal masts.
While thinking about this, I went off and started researching what was available commercially or as home-brew circuitry and software libraries for these busses and for doing occupancy detection with them, as the latter would be a good way to get my feet wet and solve my “don’t want to solder those #$@! BDL168s any more” problem.
But in the past week I’ve been sidetracked into looking at homebrew inductive-coil detection circuits.
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Recently I’ve been rethinking my approach. The BDL168 is an amazingly cost-effective solution. Ignoring the transponding part, you get 16 detectors on a board that includes a LocoNet bus interface for US$120 (street price). That’s $7.50 per detector (if you can use all 16). That’s really hard to beat for a bus-connected detector. I’d originally planned to install one per table on the layout, and my cost would have worked out to around $10 to $15 per detector on average.
On the other hand, I’m thinking that I might want to move to either a OpenLCB/NMRAnet bus (if I want a feature-rich bus for the future) or a really dumb serial bus (like S88 or C/MRI). The latter is attractive since I can potentially interface to it with an Arduino, opening up some room for home-brew devices. Of course I could do that with NMRAnet, but today that requires a US$45 shield to add to the Arduino (or one with it built in), which kind of takes away from the appeal of using $10 Arduinos to do things like drive signal masts.
While thinking about this, I went off and started researching what was available commercially or as home-brew circuitry and software libraries for these busses and for doing occupancy detection with them, as the latter would be a good way to get my feet wet and solve my “don’t want to solder those #$@! BDL168s any more” problem.
But in the past week I’ve been sidetracked into looking at homebrew inductive-coil detection circuits.
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Computer Support
A computer is part of my model railroad. Why, and how do I use it? Well, the answer to the last question is “not very much”, so far, but I have plans. I recently had to re-do the monitor support attached to the layout, and I thought I’d discuss the reason it’s there, as well as the work on the support itself.
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NMRAnet - Why You Should Care
In August, the NMRA adopted standard S-9.7.1, NMRAnet Physical Layer, and a short article about it appears in the November issue of the member's magazine. What is this, and why should you care about it?
Well, if you care about Digital Command Control (DCC) for controlling a model railroad, it's an important addition to model railroading that will enhance that. And if you don't care about DCC, it's compatible with other control systems, and you may still want to use it. Read More...
Well, if you care about Digital Command Control (DCC) for controlling a model railroad, it's an important addition to model railroading that will enhance that. And if you don't care about DCC, it's compatible with other control systems, and you may still want to use it. Read More...
Bus Wiring and November 2011 Status
DCC is often said to simplify a model railroad because it requires “only two wires”. While that’s true to an extent, most real model railroads will require quite a bit more. Or maybe I just like to over-complicate things.
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Fun with JMRI
Some weeks I don’t get much done. Well, that’s not quite true, I did a lot of work on the website this week, but the railroading time suffered. I did find some time to play with the test track I’d set up last week though, configuring JMRI to report block status based on the BDL168 outputs.
If you’re not familiar with JMRI it’s a free software package that allows a computer to interact with any of several DCC command stations that support computer interfaces, including Digitrax. It’s also available for Windows, Linux and Macs. And while not the most Mac-like program, it works, even on the ten-year-old iMac I’m using for the layout controller.
So what I have is a test track that’s an oval divided into two electrical blocks, each connected to an output of the BDL168. I named them, creatively enough, “One” and “Two”. And I used the Layout Panel editor to draw a schematic of the track. When displayed, red shows occupied (it’s configurable) and green shows clear. Even on my old computer, the change is nearly instantaneous once the locomotive crosses the insulated rail joiners from one block to the other.
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If you’re not familiar with JMRI it’s a free software package that allows a computer to interact with any of several DCC command stations that support computer interfaces, including Digitrax. It’s also available for Windows, Linux and Macs. And while not the most Mac-like program, it works, even on the ten-year-old iMac I’m using for the layout controller.
So what I have is a test track that’s an oval divided into two electrical blocks, each connected to an output of the BDL168. I named them, creatively enough, “One” and “Two”. And I used the Layout Panel editor to draw a schematic of the track. When displayed, red shows occupied (it’s configurable) and green shows clear. Even on my old computer, the change is nearly instantaneous once the locomotive crosses the insulated rail joiners from one block to the other.
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DCC Power I
After assembling the first of my DCC protection and Occupancy Detection boards, I decided I wanted to test it and get some experience with using it. So I set up my loop of test track with insulated rail joiners separating it into two halves, and connected the feeder to outputs 1 and 2 of the BDL168, which correspond to RX4 A, detectors A & B. All of these are powered by PM42 section 1. For DCC, I used my Zephyr, and for the DC supply I used the 2 Amp, 12 Volt supply I plan to use for these systems (it’s the black box just above the Zephyr in the photo above). Powering it up, nothing went “Zap!”, which I count as a success.
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A Matter of Time
Railroads have always been concerned with time. Early ones used timetables alone to keep trains on the same track from colliding. This didn’t work very well, particularly given the accuracy of mid-1800‘s pocket watches and the lack of synchronized time sources, and many lives were lost. Signaling systems and other protection methods were gradually developed. But timetables continued to be important for all trains in scheduling the use of tracks even with other systems used for protection, and timetables were required for passenger trains, as trains from different places needed to coordinate their arrival and departure at interconnection points, so passengers could move smoothly from one to the next as part of a longer journey. Railroads gradually developed standards for time-keeping (and they’re responsible for the adoption of the standard time zones used in the U.S.), and also influenced the development of clocks and watches to provide accurate and synchronized time sources.
Japanese passenger trains today are famed for their obsessive adherence to schedules, with deviations measured in seconds, not minutes. So it only seems reasonable that a model railroad of a Japanese passenger line should operate to timetable (well, eventually,I need a yard/staging tracks before that will be much fun).
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Japanese passenger trains today are famed for their obsessive adherence to schedules, with deviations measured in seconds, not minutes. So it only seems reasonable that a model railroad of a Japanese passenger line should operate to timetable (well, eventually,I need a yard/staging tracks before that will be much fun).
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LocoNet: A DCC Control Bus
DCC is really about getting power and control information to the track. But there’s another side to it: how do the commands from the throttle (the controls) get to the DCC system, and how do different parts of the DCC system communicate with each other? The first part isn’t covered by the NMRA’s DCC standards, so each manufacturer does the throttle-to-command-station link in their own proprietary manner. The second part is partially standardized, as the NMRA has Recommended Practice RP-9.1.2 Power Station Interface to describe how a command station sends commands to booster stations, but they don’t say anything about how devices like stationary decoders or occupancy detectors report their status, although there’s a draft of a standard for an “NMRAnet” control bus being developed which will probably fill this gap, someday.
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More Electrical Work
Rather than turning my attention immediately to the Riverside Station scene, I decided to get the electrical systems ready for the eventual use of the two “ground level” loops, which will require DCC. And that meant I needed to finalize my plans. And although most of them had been worked out last year, and revised (in my head if nowhere else) over the winter, there was still a bit of planning needed before I was ready to start cutting wire. This had to encompass the DCC systems (both power and the LocoNet control bus) as well as the various power strips to supply them, and some additional power supplies for eventual LED lighting. I’d started thinking more intensely about this while I was working on the wiring recently, but needed to bring that to conclusion and write down the results.
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