There are plenty of block detection units out on the market that can control signal lights for CTC.
Question is, once the train is on a main, and approaches a red signal, how can you get that train to stop automatically? Are there any products which broadcast just a "stop" command for a block?
If I shut down the block power for the next block, and the next block is occupied, then occupancy detection won't work for the next block (for trains that exceed more than one block)
Lenz has asymetric DCC with their railcom (on Lenz Gold and Silver series decoders) These decoders will have the train automatically stop when a half power rail is found. But this isn't standardized.
Anybody have any ideas?
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
Don,
Since commands are addressed to a particular decoder, there really isn't such a thing as "a stop command for a block".
What you need is software that knows what the signal indications are and can also "remember" where a particular train is and it's direction, based on that block detection, and then issue the appropriate commands to the appropriate decoder. Of course, this requires that your DCC system (and separate signal and occupancy systems, if that's how you're set up) has an interface to the computer running that software.
I believe Railroad & Co has that ability, and I also think some folks have written JMRI scripts that will do it.
Steve
DigitalGriffinQuestion is, once the train is on a main, and approaches a red signal, how can you get that train to stop automatically?
Are there any products which broadcast just a "stop" command for a block?
1. Is this DC, DCC, DCS, Railcommand, or other.2. Any preference on type of block detectors.3. Is there a computer involved.4. What sort of budget are we dealing with.5. is this for a roundy round layout or should we consider the blocks independent and in line.6. Is there one block per signal or multiple.7. Are train cars equipped with resistors on the wheels so a "current" detector can sense them (related to #2 above).8. Do all this have to be off the shelf parts (as implied) or is there a williness to build custom circuits for oneself.
Signalling is the most complicated element of a model railroad, add automatic control and it is doubly so.
If the 'signal' for the block ahead is 'red', then you want the engine to stop before you pass the signal - correct? With DCC(and some transponding) so you can tell when the engine is - it can be done. It will take some JMRI scripts & detection equipment, or similar commercial software. Be willing to invest some $$$ in your project!
Jim Bernier
Modeling BNSF and Milwaukee Road in SW Wisconsin
>1. Is this DC, DCC, DCS, Railcommand, or other.
DCC, digitrax system.
>2. Any preference on type of block detectors.
Preferably current sensing so something like Digitrax BDL-168 block detector can be used. (This also has connection for signal heads)
>3. Is there a computer involved.
No. The point is to automate it, so the less than computer savy can replace bad "black box" components, and not have to have a programming degree, or buy transponders.
Computers fail, break down, and need changing with layout changes. Although I'm extremely computer savy, most people are not. This has to be a universal easy to use solution.
>4. What sort of budget are we dealing with.
Variable budget. But this is a whole layout conversion from an older relay based DC block based control system. So we are talking couple thousand.
>5. is this for a roundy round layout or should we consider the blocks independent and in line.
Two mainlines and a branchline.
>6. Is there one block per signal or multiple.
One block per signal
>7. Are train cars equipped with resistors on the wheels so a "current" detector can sense them (related to #2 above).
Yes. This is mandatory. Trailing car MUST have a resistance across the wheels of 1000 ohms or less.
>8. Do all this have to be off the shelf parts (as implied) or is there a williness to build custom circuits for oneself.
I can build my own circuits. It can't be anything fancy though like a PIC chip. Just diodes, transistors, rectifiers, resistors, and caps. But off the shelf is preferable.
I do know NMRA RP 9.2.4 has a fail safe mode. I can A/B relay the section. If Block 1 is occupied DCC, then switch Block 2 to DC by relay. If I a/b the section to DC, all DCC decoders are supposed to stop by decelerration. All dual mode decoders (both DC and DCC compatible) are supposed to accel/decel based on the DC voltage. The later is the kicker. QSI/Tsunami's start at 9V. Other non-sound DCC decoders start at 3V. If I broadcast a 9V across the rails, then non-sound DCC dual mode decoders will keep chugging along. If I do only ~3Volts, then the sound decoders stop dead in their tracks as the decoder shuts down. A smooth stop is preferable so things don't come grinding to a halt with possible derailments on longer trains. (Plus it's more protypical)
And there is a universal "STOP" command that stops everything. I could A/B Relay the block to a booster that is just broadcasting a "STOP" command. But I'm not so fond of this idea as seperate boosters for 36 block sections total = $$$$$$$$.
As you can tell, I'm brainstorming. This is research for converting a club from DC->DCC and it has to be bullet proof, standardized, and non proprietary (It has to work based off NMRA standards for DCC)
If anybody has any ideas, I'm more than willing to listen.
OK some good information to work with now. I'll puzzel over it for a while. In the mean time...
DigitalGriffinTwo mainlines
>7. Are train cars equipped with resistors on the wheels so a "current" detector can sense them Yes. This is mandatory. Trailing car MUST have a resistance across the wheels of 1000 ohms or less.Depending on the exact detector selected this resistance might be able to be increased to 10,000. Some of the new detectors are very sensitive. I once calculated that for our clubs main yard current draw for just cars with one 1000 ohm axle each would be something like 4.5 amps.
>7. Are train cars equipped with resistors on the wheels so a "current" detector can sense them Yes. This is mandatory. Trailing car MUST have a resistance across the wheels of 1000 ohms or less.
I do know NMRA RP 9.2.4 has a fail safe mode. And there is a universal "STOP" command that stops everything. I could A/B Relay the block to a booster that is just broadcasting a "STOP" command. But I'm not so fond of this idea as seperate boosters for 36 block sections total = $$$$$$$$.Unless I am mistaken, even the universal stop command won't work. To use the stop one would have to have separate COMMAND units on each detection block, not just separate boosters - that is more costly and makes a whole new set of syncronization issues to deal with.
I do know NMRA RP 9.2.4 has a fail safe mode. And there is a universal "STOP" command that stops everything. I could A/B Relay the block to a booster that is just broadcasting a "STOP" command. But I'm not so fond of this idea as seperate boosters for 36 block sections total = $$$$$$$$.
Just skimming through 9.2.4 ... hmmm that would be a fairly bizzare unintended way to use that feature.
DigitalGriffin...And there is a universal "STOP" command that stops everything. I could A/B Relay the block to a booster that is just broadcasting a "STOP" command. But I'm not so fond of this idea as seperate boosters for 36 block sections total = $$$$$$$$...
You are absolutely right about the universal "STOP" command, short address 0 is the broadcast adddress and sending a stop command to this address will make any NMRA compliant decoder stop, no matter what it's address is. You do not have to have a seperate booster for each block, however. You have can have one booster broadcasting the stop command and each section switches between your regular booster and the stop booster depending on the signal aspect. Take a look at some of the products available here(including a DCC broadcast stop signal generator, although you can also configure the programming outputs of a DCS100 for this) : DCC BitSwitch
I forgot to mention the brakedist.pdf that shows how to setup a brake district using a DCS100 and one additional boster.
Robert, thanks for the heads up.
The ballast bulbs look like Joe Fugate's automotive bulb solution for short detection/protection. I was wondering how they were going to keep from shorting out between blocks (when a metal wheel/truck crosses sections with different voltages)
Looks like I have two viable solutions now to present! Either DC or DCC braking section via DCS100 + additional booster.