This post just to get this topic from 2009 to 2011
N

Now a diagram of what I have in mind and the necessary questions/

1. What other S88 Contacts do I need, and where do I put them.

2. The train coming from Station 1 (On the Left will always travel straight. Eg LH Running.

3. the train starting its run will always go via the loop again LH Running.

4. If the train from Station 2 in NOT completly within the Loop the train from station one (on the Straight) will have to stop before the beginning of the RH End of the loop.

5. IF the train from Station one has not completely cleared the track at the LH End of the loop the train in hte loop will have to stop.

I was thinking of Computer control so as to give a gradual stop. OR a S88 contact far enough back to set speed 0.

A signal on hte straight before beginning of loop to go red IF RH Single track was Occupied.
a Signal at RH end of Loop if RH Single line was occupied

What else??

Nev,

You don't need train detection..

Now that you understand blocks and s88, it is time for the next lesson.. It is routes.. A route is a path between two locations traveled by one loco at a time.. I will use your diagram as the basis of the description, but I have added four more needed s88 contacts - they are numbers 5,6,7 & 8. You will understand why they are needed shortly..




Route 1 comprises s88 numbers 3,4,5,6
Route 2 comprises s88 numbers 1,2,7,8
Route 3 comprises s88 numbers 6,2,1
Route 4 comprises s88 numbers 8,4,3

I will leave off signals and assume that there is only one way to go in each direction..

When you set up computer control you tell the software (e.g. WinDigipet) which s88 contact has your loco.. In this case, train 1 is stationed at s88 port 1 and train 2 is at s88 port 3.

When you start the program in automatic mode (WinDigipet calls these automatic tours - other programs have equivalents), the computer will select one of the s88 ports to check - we assume it is port 1. First question the computer has is, "are ports 2,7 and 8 clear?". If the answer is yes, it switches route 2 and moves train 1 by changing the throttle to the default start speed. When train 1 hits port 7 it slows to the slower speed and is stopped at port 8. The computer knows that train 1 is on port 8, because there is no where else for the train to go.

The computer then checks to see if ports 4 and 3 are clear (route 4). In this case, they are not because train 2 is on port #3. So the train stays at the station (or siding).

Meanwhile the computer knows that train 2 is on S88 contact 3, so it checks route 1 by confirming that ports 4,5 and 6 are clear. They are clear, so the computer switches route 1 and moves train 2 by changing the throttle to the default start speed. Train 2 slows down on contact 5 and stops on contact 6. It knows that train 2 is on port 6, because there is no where else for the train to go.

The computer then checks to see what routes are available from s88 contact 6 and confirms that route 3 is available as ports 2 and 1 are free. Train 2 moves off, slows down on contact 2 and stops at contact 1. Train 2 is now at contact 1.

Meanwhile train 1 is on contact 8 and the computer now confirms that route 4 can be switched as ports 4 and 3 are now clear.. Train 1 moves off, slows down on contact 4 and stops at contact 3. Train 1 is now at contact 3.


More advanced options

Software like WinDigipet can make this more interesting by allowing you to have two selectable routes at contacts 1 and 3. so we can add:
Route 5 1,2,6,5
Route 6 3,4,8,7
Route 7 5,4,3
Route 8 7,2,1

The difference is that at contact 1 with train 1, the computer tests and selects either route 2 or route 5. If it chooses route 5, the train 1 ends up at contact 5. When the computer tests the routes for contact 3 (train 2), it MUST select route 6 as s88 contact 5 is occupied by train 1.

First rule is that a computer will not let trains go together.. It scans s88 ports one at a time (very fast so that it looks like they move at the same time) and switches a route (if the destination contacts are free) and sends a train off along the route before checking the next s88 port..

Secondly, the computer looks at routes to determine if a block is free and not the destination s88 port (I used ports in the above example to make the process easier to understand).. In the example above, if train 1 was really slow such that it had not reached s88 contact 5 by the time the computer was testing the routes for contact 3 (train 2), it would select route 6 as route 5 is active and train 1 is on its way to s88 port 5..

Thirdly, this all happens quickly so you need to add a delay on ports 1 and 3. Otherwise the Preisers will not have enough time to get off the train before it reverses direction and takes off..

Does this make sense for you?
Cheers

Edited by user 23 May 2011 12:40:04(UTC)  | Reason: Not specified

The way to study it is to build the layout using two turnouts and some track, mark the position (and number) of the 8 s88 contacts and use two wagons to simulate the two locos.. When you understand how this works you have the basic knowledge to implement computer control on the larger layout..

Cheers