Video 15: Using iTrain Tutorial Series - Deadlocks and Critical Blocks

[@Rule1ModelRailways]

My head hurts! Great video!

[@bobfuller]

LOL - I'll put a health warning in the tutorials in the future!! :)

[@Haymarket47]

Wow, this would have undoubtedly led to many hours of head scratching/problem solving - indeed it might still do😂. Thanks again sir for your excellent tutorial.

[@bobfuller]

You're welcome!

[@Julian-zc4ik]

Thanks Bob, brilliant video. Definitely one to go back to a few times

[@bobfuller]

Yes, a good one for exercising the brain, but if you replay it a few times it will hopefully fall into place.

[@MissedrBones]

Very well explained once again. Thank you.

[@bobfuller]

Glad it was helpful!

[@johnwybourn9239]

Thank you so much for the time you are putting into these presenations. I think the quality of your deivery is absolutely top draw! And as other people have commented so much better than reading the manual. You must do this professionally to be so good at it! And if you dont you should. John

[@bobfuller]

Thanks for the kind comments, John. Much appreciated. The videos are hopefully a good aid to gaining a better understanding of the manual, but the manual is still the bible and should be read to get the most out of iTrain.

[@AndreasSchumann-m1e]

Very interesting problem solving. Thank you for explaining it. I never would have gotten that by just reading the manual. There is to remarks from my side, however: 1. Moving DB_POL from D8 to D1 while moving DB_IC from D1 to D9 and DB_CAR to D8 only works, if D4 is set to critical in both directions, next and previous. If D4 is set to critical only in the next direction, it is reserved by DB_CAR because it is performing a shunting operation and switching directions when arriving in D4. The video suggests otherwise, and in my view this should be corrected in order to no longer confuse future viewers. It took me a full day to make that work. 2. I wonder whether it is possible for itrain to cope with two required direction shifts. For example, moving DB_POL D8to D1 and moving DB_IC from D1 to D8. This causes a deadlock because it would require DB_POL to enter D10, switch directions, let DB_IC pass by, move to D4, switch directions again and then finish the journey to D1. Any comments on that one?

[@RonArmes]

Another big thank you Bob. I look forward to seeing your new tutorials, but as you say, I will have to play this one back a few times to get my head around it. Great stuff!

[@bobfuller]

Have fun!

[@flinthillsmodelrailway]

excellent video again Bob - learnt so much about deadlocks and critical routes . i've not had to add any of these to my layout however its got me now checking if i should !! i think i should have also paid attention at chess

[@bobfuller]

LOL. Glad it was helpful, Geoff.

[@susangeorginagraves854]

Thanks for this video. However, I have a question which you did not cover. If a train is in d8, and is not selected to move, so it is stationary. You select train in d10 to goto d8, what you have said would not prevent a deadlock, as the train would be allowed to proceed in your d4 critical status, as d5, d6, d7 will be free, so it would allow the train to proceed all the way down to d7 before hitting the deadlock. So would you have to declare d7, d6, d5 as critical block status in both directions ( previous & next ) in order to prevent this?

[@bobfuller]

Good question, Susan. Bare with me. I'm working on something at the moment and will provide a reply in a day or so. It requires more than a yes/no reply.

[@bobfuller]

Hi Susan, Thanks again for the great question. There's a few things that I should try to clarify here. The example I have shown of a single track with multiple blocks (D5, D6, D7) leading to a single terminating point at D8 is not really prototypical. Usually, there would be passing loops between the blocks, or there would be multiple sidings at the end of the track to move into. So it was perhaps not a good example to show. However, the example does help to highlight how iTrain makes certain decisions in certain circumstances. The thing that makes the difference is the direction that the train in D8 is pointing. If the train in block D8 is facing to the left (so pointing in the same direction as the train that we are routing from D10), then the blocks (D7, D6, D5) can be reserved to the left as they are moving in the same direction. This way a single track (that continues to the west after D8, if there was one) has a higher capacity, because it can allow multiple trains in the same direction. If the train in block D8 is facing to the right (so pointing against the direction of the train that we are routing from D10), all the blocks (D7, D6, D5) cannot be reserved in the other direction. Try changing the direction of the train in D8 and then try the route again and you will see what I mean. Blocks D4, D5-D7 will now not be reserved, and the train in D8 can be moved out to make room. Once the train is clear, the train in D10 will then automatically route to D8. But, of course, you are right that in this case it is not what you want as D8 is a dead end and not followed by a turnout and a station with multiple tracks as I would expect on a single track divided in multiple blocks. The work around, if you did have a section of track as shown in my example, would be to make D4-D7 all critical blocks, or make it all a single block. So it is not the position, but the direction that makes the difference.

[@bobfuller]

Hi Susan. Some even better news. In version 5.0.6 there will be improvements in the way that iTrain handles terminated track, which will address this sort of scenario.

[@kite7214]

Thanks a lot for this Bob. Perhaps next time you could use 3 dissimilar trains eg D6510, DB Car and A.N.Other to make the viewing clearer. But a good job overall. Thanks again. Keith

[@goodisonroadmodelrailway6798]

Great Stuff! Keep up the good work! Cheers JC

[@bobfuller]

Thanks, will do!

[@rogerstonham3631]

Bob. Am starting to plan a new layout which will be automated. Looking at options of itrains or traincontroller. Have watched all the videos over the last week and they are extreemly helpful. Will start to use put my planned layout into itrains to get some ideas. It will have three crossovers and would be interested to know how to deal with these. Again thanks for a great series of videos.

[@bobfuller]

Hi Roger, glad you are finding the tutorials useful. Is there something specifically about the crossovers that you need help with? Page 95 of the manual gives a pretty good description of how they operate. I had not planned to do a specific tutorial on them.

[@rogerstonham3631]

@@bobfuller my only concern is switching their polarity - the answer seems to be treat it as a 4 way slip which is a bit of a cop out.

[@bobfuller]

Not sure why it is a cop out. Treating a standard cross over as a 4 way slip gives you so much more flexibility. You just enable the two straight states and disable the two branched states. Then you can double click on the output columns to configure the state as you wish. Exactly what type of cross over do you have (e.g. brand and model)? The polarity switching is normally handled by your auto-reverser or two frog juicers depending on what you are using, isn't it?

[@damenfeld]

Do you mean a crossover, single or double slip? A crossover only requires to be named in iTrain to ensure that iTrain will reserve it when on a route to stop another train trying to crossover at the same time. A single slip and a double slip require to be named and have addresses input for the number of motors that you have driving the slips. Some singles and doubles only need one address, some double slips need 2 addresses. ITrain doesn’t consider polarity switching of the track on turnouts or reverse loops and this must be handled by the design of the crossover, slip or reverse loop. Commonly the polarity switching is undertaken by the turnout motors though you can use electronic autoswitchers which rely on short circuit detection.

[@rogerstonham3631]

@@damenfeld I understand about polarity switching as for everything I would do it via the tortoise point motor. However I do need to switch polarity on a crossover. Ideally I would want itrains to implement the crossover as a point so that I could trigger a relay to do the change. However the manual says configure it as a slip which would work just a bit 'mickey mouse'.

[@ryteker]

Bob, yet another great video, I have programmed the same demo to run/test it, but I'm not getting the same results as your tutorial shows. I suspect its because I'm not fully understanding the correct use of the Stop Positions in the Direction Previous and Direction Next. I appreciate that they are for allowing the loco/train to stop at a given position, but not sure of if they should be positive of negative values, I've tried to fathom it out from the manual, but could not find anything that explained it clearly (probably me not seeing wood for trees !) Is is possible to obtain/download a copy of your tutorial so that I could compare it with my efforts to hopefully figure it out ... or maybe indicate if the blocks Stops for the Directions previous and next should be positive or negative values ... Roy

[@damenfeld]

Roy, if you ask the question on the iTrain forum then we will be able to help you there. berros.eu/itrain/forum/viewforum.php?f=1 Please also post your layout file (tcdz) when you create your post to enable us to see what is wrong.

[@royendersby2980]

Hi Bob, I'm getting the right results but my trains are still not clearing down the blocks as they progress. Some will clear when I manually select them, then the next route appears. I can post in the forum if that helps.

[@bobfuller]

Hi Roy, yes, it will be much easier if you can post in the forum and add your layout file as an attachment. Then we will be able to see what is going on.

[@royendersby2980]

@@bobfuller I thought I would give you an update. When running trains on my physical layout, rather than the simulation, it works fine. Blocks and routes are cleared. I just need to tweek the stopping points. One point. I assume on a 2 car DMU and one is a dummy car the offset needs to be set on the first powered or pickup axle?.

[@bobfuller]

@@royendersby2980 That's good to hear. Nicely done, Roy! Yes, you take the offset from the first powered or pickup axle.

[@Modelrailwaysforfun]

That would have taken hours to understand from a manual. now practice will make it perfect.(eventually)

[@bobfuller]

Yep, the only way to really learn is to put it into practice. Enjoy!!