Signaling on the CCRSignaling on the CCR

Tyler Raulin

Overview of SignalsOverview of SignalsRules:

– 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

RequirementsRequirements

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

SolutionsSolutions

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

Creating Data StructuresCreating Data Structures

Next Photocell– Clockwise/Counterclockwise Direction– Straight/Curved Track

Next Turnout– Clockwise/Counterclockwise Direction

Light Status– Clockwise/Counterclockwise Direction– Straight/Curved Track

Setting Lights for a trainSetting 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

Setting Lights for TurnoutsSetting Lights for Turnouts

Scroll Through Next Photocell Data Structure– If value == NEEDSTURNOUT

Check the status of the turnoutIf we don’t have the turnout

– Set the Light to RED

Setting Lights for Turnout in Setting Lights for Turnout in other Directionother 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

Resource ManagerResource ManagerFunctions 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

Train ControlTrain Control

Graphical interface that displays information about each train

Connected to a train and its valuesDisplays the lights that the train sees as it’s

moving down the trackChange Direction Button Modified to

recover from deadlockToggle Turnout Button Added

Train Control…cont.Train Control…cont.

Change DirectionChange 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

Toggle TurnoutToggle 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

Toggle Turnout…cont.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

ExceptionsExceptions

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

MethodologyMethodology

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

DemonstrationDemonstration

One TrainTwo Trains

Questions?Questions?

HASNOTURNOUT

NEEDSTURNOUT

NextPhotocell

NextPC Data Structure

NextTurnout

NextTO Data Structure

Photocell Status

PC Status Data Structure

Light with Two Trains

Deadlock Issue

Deadlock Issue Resolution

PC Manager Issue

Semaphors

StrategiesStrategies

LogicDiagramsPseudo-codeTesting

KnowledgeKnowledge

Designing and coding data structuresCreation and Relation of classesAllocation of ResourcesDeadlocking and recovery from itEvent programming and the use of

interrupts and polling

ExtensionsExtensions

Combine the Batch and Interactive file modes, implement record and playback

Work out issues with direction changes or toggling turnouts

AdviceAdvice

Come up with a strategy and stick to itKeep the professor in the loop of your

projectTry to devote large chunks of time

THANK YOU!!!THANK YOU!!!

HASNOTURNOUTHASNOTURNOUT

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

NEEDSTURNOUTNEEDSTURNOUT 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

Next PhotocellNext 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

back

Next TurnoutNext Turnout

Initialize all memory locations to HASNOTURNOUT

Assign the turnout number to each locationOne 2-dimensional matrix 2 x

MAXPHOTOCELLSColumn 1 is for ClockwiseColumn 2 is for Counterclockwise

back

back

Photocell StatusPhotocell 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

back

Setting Lights with Two TrainsSetting Lights with Two Trains

back

Deadlock IssueDeadlock 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 BLOCKEDSet the photocell you are blocked at to RED

back

Deadlock Issue ResolvedDeadlock Issue Resolved

back

Train Resources vs. PC Train Resources vs. PC ManagerManager

Train Resources were updated in AllocateResources

UpdateResources calls AllocateResources

AllocateResources is not always called if BLOCKED

back

Toggle Turnout…cont.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

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