There seems to be very few Plc control systems in model railroading, probably due to cost. I am in the Plc business and have these systems laying around. The lighting, signaling and train location on my 8'x12' DC HO layout is totally controlled by an Allen Bradley Plc 5-30 in a 16 slot chassis, with a 8 slot chassis for the freight yard. All the houses on my layout have the floors divided and the second floor divided in two, each house has three lights in it with it,s own timer. The Plc controls the time the lights are on in each section of the house, making it appear that the house is occupied. I have magnetic reed switches installed between the rails, and small magnets under each engine. All of the traffic lights are Plc controlled. As a train approaches a grade crossing with a traffic intersection adjacent to it, the traffic lights turn red crossing the tracks and blink yellow paralleling the tracks. All train signals are Plc controlled. I use three voltages for lighting, 14 vac for area lighting, (incandescent), 10vdc for signaling (LED), and 9vac for residential interior lighting. When using a Plc, the possibilities are endless. I use Lionel 1033 units for for all ac power requirements an 1033 with full an half wave rectifiers for dc power. What I don't have is a lot of wall warts and circuit boards for grade crossings and traffic lights and other requirements. Even the welder in my roundhouse is just 2 LEDs with the Plc randomly firing them. What I do have is a whole lot of wiring and a couple hundred terminal boards. I am not yet controlling the motion of the trains, that is the next step.
Hi!
It took me awhile to realize this, but sometimes what we perceive as a dumb" question - and everybody knows the answer but me - is really not the case. Soooo, I have learned not to be embarrassed and just go ahead and ask the "dumb" question......................
With that being said, "What in the heck is a Plc control system?"
ENJOY !
Mobilman44
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
PLC, programmable logic controller, is a computer, designed for industrial applications. They range in size, from small 8-16 I/o (inputs and outputs) to large systems that can support unlimited I/o, both digital and analog. The advantage of this system is, you don't have to purchase the electronics to operate most devices on your layout. The disadvantage is cost. Cost can go from less than a hundred buck. To several thousand dollars. The software, alone, to program my Plc is 5 grand a copy. The Plc that I am using is way over kill for this application an would cost between 20 and 35 thousand, but I had all of the necessary hardware and software in stock . There are cheaper and more user friendly systems out there to be considered for model railroading.
ccg
Most of what we try to do with layout controls is just consumer-grade scaled-down versions of industrial controls. Based on that, I'm often amazed that what is sold for home layouts works as well as it does, especially with the varying degrees of electrical prowess that model railroaders (as a population) have.
In the late 1990s, I was working for a company that manufactured industrial PCs. To demonstrate a new line of control software that subsidiary ArborCoast Software was releasing, they chose to commission a custom-built HO layout to demonstrate their flowchart-based control software and the parent company's then-new touchscreen industrial mini-PCs.
The layout was five feet wide by 18 feet long, with three loops of trains crossing each other at grade at various locations, and a point-to-point trolley line that crossed all of them. Off-the-shelf optical sensors and various types of proximity detectors sensed trains at the crossings and prevented collisions by cutting power as needed. They used a couple of brands of PLC to demonstrate that the PCs could interface to them.
At one end of the trolley line, they had a multiple-horsepower industrial spindle motor turning one of the old IHC spinning chair amusement park rides. When the trolley would arrive, it would turn the ride slowly, stopping it every few degrees to simulate loading, then spin it up to ride speed. After a minute, it would slow down, go through the unloading process, then stop as the trolley pulled away.
Throwing turnouts to route trains, and control of various small accessories around the edge of the layout were handled using a number touchscreen PCs mounted around the edge of the layout.
It was a huge hit at the trade shows it visited for about a year.
One of the model railroaders in town built the layout portion, then helped install the industrial controls. He learned enough about industrial control components from this project that he was able to get a job with Siemens, working on their mail-transport and sorting systems for the US Post Office.
I seem to recall that they had over $10,000 into benchwork (including labor), track and equipment before they applied over $30,000 worth of control hardware to it. And this was without anything that looked like scenery as we know it. It did have a hard marble-like paint finish that was very difficult to spike track into.
If anyone thinks that DCC accessory decoders and block detection are expensive, they've never priced it out using industrial controls...
-Fritz Milhaupt, Publications Editor, Pere Marquette Historical Society, Inc.http://www.pmhistsoc.org
However, there are some good reason why the industrial stuff costs so much. Robustness is just the start - a model motor, even Large Scale, needs a fraction of the power of a machine tool spindle motor or even the axis drive servos. Then there's the whole safety issue - if your DCC controller fails to stop your loco heading towards a drop through an opened lift bridge, the worst that happens is you damage a few hundred dollars of brass locomotive. If the industrial control fails, you can seriously injure or kill the operator, or it it's controlling something more than a single machine tool, you could potentially threaten an entire city.
Kinda goes along with what I said, it's certainly neat stuff, and as my first job out of college involved working in a CNC machine shop, all that sort of stuff really does interest me. But unless you have a source of equipment for free or blow out cost, it's far too expensive for model railroad use. But then, I don't think anyone was suggesting to go out and buy brand new industrial controllers and interfaces to run their trains. If you can get or have one, and want to apply it to model railroad use, absolutely nothing wrong with that, and it would result in some pretty cool possibilities. I know I can't wait to see the amusement park modules I mentioned up and running.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
ccgThere seems to be very few Plc control systems in model railroading, probably due to cost. I am in the Plc business and have these systems laying around. The lighting, signaling and train location on my 8'x12' DC HO layout is totally controlled by an Allen Bradley Plc 5-30 in a 16 slot chassis, with a 8 slot chassis for the freight yard.
pic micro-controllers are around a $1 and the programmers seem to be around $10 on ebay. I was able to download an assembler years ago for free. They include PWM outputs. Do you think pic processors would be a less expensive and more flexible alternative than using PLCs?
greg
greg - Philadelphia & Reading / Reading
rrinker If the industrial control fails, you can seriously injure or kill the operator, or it it's controlling something more than a single machine tool, you could potentially threaten an entire city. --Randy
If the industrial control fails, you can seriously injure or kill the operator, or it it's controlling something more than a single machine tool, you could potentially threaten an entire city.
Way back in the early 1980's when PLC's were a new idea, I designed, programed and supervised the installation of some of the first ones to be used in the Baltimore waste water treatment system.
Four Cutler Hammer PLC racks, that each held 10 cards IIRC, replaced about 120 control relays in one of the city's most critical sewage pumping stations. They controlled three 700 HP, 2400 Volt, variable speed motors connected to three sewage pumps with impellers about 12' in diameter and about 4 feet high.
To my knowledge those PLC's might still be running that station.
As a long time designer of industrial control circuits, I have often considered the use of PLC's for model train applications - but the cost is crazy.
So, I'm still using relays for the trains, signal system and turnout controls. 24 volt ice cubes I can buy in bulk for $3 apiece or less. And they work just fine. Cheaper than PLC's, cheaper than DCC, cheaper than PC software and interfaces for signaling.
Sheldon
gregc ccgThere seems to be very few Plc control systems in model railroading, probably due to cost. I am in the Plc business and have these systems laying around. The lighting, signaling and train location on my 8'x12' DC HO layout is totally controlled by an Allen Bradley Plc 5-30 in a 16 slot chassis, with a 8 slot chassis for the freight yard. pic micro-controllers are around a $1 and the programmers seem to be around $10 on ebay. I was able to download an assembler years ago for free. They include PWM outputs. Do you think pic processors would be a less expensive and more flexible alternative than using PLCs? greg
The problem with most model train applications is the need for lots of inputs and outputs, but the application of relatively simple programs. I/O counts drive up hardware costs with PLC's.
Consider signaling - and output for each light in each signal.
I don't even know any current pricing, but at 1980 prices it would outrageous.
Most certainly using PICs would be cheaper than an industrial PLC. PIC chips can be had with insane numbers of I/O pins, and if you're willing to make the code slightly more complex, you can easily multiplex them to get many many more, all from an inexpensive chip plus a couple of inexpensive decoder ships.
Look, for example, at the Digitrax SE8C - it's a board that sells for ~$100 and controls 32 signal heads, each with 3 lights. Plus it has 8 inputs for block detectors, 8 outputs for Tortoises or similar, and 8 more inputs for buttons to manually operate the Tortoises.
Regardless of the DCC system you use, strining a Loconet (does NOT need any Digitrax command stations) is probably the most cost effective option out there, AND has the most variety of I/O options, from multiple vendors AND a ton of DIY stuff.