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Signaling on the CCR

Signaling on the CCR. Tyler Raulin. Overview of Signals. Rules: Red Light There is a train in the next section of track The turnout is not turned correctly for the train to continue Yellow Light There is a train two sections away from the train Green Light

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Signaling on the CCR

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  1. Signaling on the CCR Tyler Raulin

  2. Overview of Signals • Rules: • Red Light • There is a train in the next section of track • The turnout is not turned correctly for the train to continue • Yellow Light • There is a train two sections away from the train • Green Light • The next two sections of track are clear • There are no turnouts blocking us from continuing

  3. Requirements • Implement virtual signals in each cab to reflect what each train would see • Redesign the CAB’s human interface so that it is useful • Implement existing deadlock avoidance, detection, and removal algorithms for trains controlled interactively • Allow User to toggle turnouts instead of controlled by the operating system

  4. Solutions • Create Data Structures to store the values of the Next Photocell, Next Turnout, and Light Status • Create a Light Manager Class which checks and updates these data structures • Tie the Light Manager Class into the existing Resource Manager Class and Train Control Class

  5. Creating Data Structures • Next Photocell • Clockwise/Counterclockwise Direction • Straight/Curved Track • Next Turnout • Clockwise/Counterclockwise Direction • Light Status • Clockwise/Counterclockwise Direction • Straight/Curved Track

  6. Setting Lights for a train • All Lights are initialized to Green • Red Lights are placed outside the section for trains that wish to enter • Yellow Lights are placed in the next section after the Red Lights

  7. Setting Lights for Turnouts • Scroll Through Next Photocell Data Structure • If value == NEEDSTURNOUT • Check the status of the turnout • If we don’t have the turnout • Set the Light to RED

  8. Setting Lights for Turnout in other Direction • Scroll Through Next Turnout Data Structure • If value != HASNOTURNOUT (there is a turnout) • If Turnout is Straight • Set Curved Light to RED • Else • Set Straight Light to RED

  9. Resource Manager • Functions used or adjusted: • OnTimer • Calls the UpdateLights function • HandleArrival • Called when direction is changed in the Train Control • UpdateResources changes the values for each train instead of AllocateResources

  10. Train Control • Graphical interface that displays information about each train • Connected to a train and its values • Displays the lights that the train sees as it’s moving down the track • Change Direction Button Modified to recover from deadlock • Toggle Turnout Button Added

  11. Train Control…cont.

  12. Change Direction • When Button is clicked • The train becomes active • The direction and the next and previous photocells are switched • We handle an arrival with the new previous photocell

  13. Toggle Turnout • Giving the user control over the turnouts causes many issues: • When can the turnout be adjusted • Who can adjust the turnout • When do we no longer have possession of the Turnout

  14. Toggle Turnout…cont. • Use an array of semaphors to not allow a turnout to be toggled while a train is in that section of track • This is a critical section of code that must not be interrupted

  15. Exceptions • Change direction will cause issues if reversed out of deadlock, then reversed again • If train1 is blocked at a turnout and train2 goes through the turnout the other way, we are unable to toggle it back once train2 has left

  16. Methodology • Dive right into the code, make adjustments and see results • Draw up ideas on paper before writing code of my own • Test my results with as many scenarios as I can think of • Use Log file to determine values at each point in the process

  17. Demonstration • One Train • Two Trains

  18. Questions? HASNOTURNOUT NextPhotocell NEEDSTURNOUT NextPC Data Structure Light with Two Trains NextTurnout Deadlock Issue NextTO Data Structure Deadlock Issue Resolution Photocell Status PC Manager Issue PC Status Data Structure Semaphors

  19. Strategies • Logic • Diagrams • Pseudo-code • Testing

  20. Knowledge • Designing and coding data structures • Creation and Relation of classes • Allocation of Resources • Deadlocking and recovery from it • Event programming and the use of interrupts and polling

  21. Extensions • Combine the Batch and Interactive file modes, implement record and playback • Work out issues with direction changes or toggling turnouts

  22. Advice • Come up with a strategy and stick to it • Keep the professor in the loop of your project • Try to devote large chunks of time

  23. THANK YOU!!!

  24. HASNOTURNOUT • In this case (in the clockwise matrix): • Photocell 2 would have value of 7 in the straight column • Photocell 2 would have a value of HASNOTURNOUT in the curved column back

  25. NEEDSTURNOUT • In this case (in the counterclockwise matrix) • Photocell 13 would have a value of 15 in the straight column • Photocell 13 would have a value of NEEDSTURNOUT in the curved column • Photocell 14 would have a value of NEEDSTURNOUT in the straight column • Photocell 14 would have a value of 15 in the curved column back

  26. Next Photocell • Initialize all memory locations to HASNOTURNOUT • Individually assign values for whichever is the next photocell • Two 2-dimensional matrices 2 x MAXPHOTOCELLS • One for Clockwise, one for Counterclockwise • Column one is straight, column two is curved • Never adjusted after values are first assigned back

  27. back

  28. Next Turnout • Initialize all memory locations to HASNOTURNOUT • Assign the turnout number to each location • One 2-dimensional matrix 2 x MAXPHOTOCELLS • Column 1 is for Clockwise • Column 2 is for Counterclockwise back

  29. back

  30. Photocell Status • Initialize all memory locations to HASNOTURNOUT • Initialize all lights to be GREEN • Two 2-dimensional matrices 2 x MAXPHOTOCELLS • One for Clockwise, one for Counterclockwise • Column one is straight, column two is curved • UpdateTrackLights( ) changes the values on a timer in the Resource Manager back

  31. back

  32. Setting Lights with Two Trains back

  33. Deadlock Issue • These two trains are technically seen as being in the same section • They look to the next light and see GREEN • We need to check if blocked during UpdateLights() • If BLOCKED • Set the photocell you are blocked at to RED back

  34. Deadlock Issue Resolved back

  35. Train Resources vs. PC Manager • Train Resources were updated in AllocateResources • UpdateResources calls AllocateResources • AllocateResources is not always called if BLOCKED back

  36. Toggle Turnout…cont. • When Train Arrives at photocell and is BLOCKED by a turnout • It will toggle the turnout if able • Then Set the semaphor to 0 to prevent toggling • Semaphor is 1 when train leaves back

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