Track Object

The track object contains functionality used for track management (switching movers between different tracks). In includes functionality for:

Attaching a track hardware ID number to this object
Assigning a user-friendly numerical TrackID for use in code
Finding and addressing all movers on a track

Use

Tracks are a software defined group of motor modules that can be grouped together independently of the physical machine layout. Tracks allow you to switch movers between different groups of otherwise disconnected motor modules. A common use case is an oval system layout with a reject spur. Movers typically travel around the oval during normal production, but stop at a track "switch" which moves between the oval and a separate reject spur.

The track object is only necessary when using track management. For most applications that utilize a single, closed loop track the Track object does not need to be addressed directly. Movers, zones, stations and position triggers all reference a track internally but are set with defaults of TrackID 1 which is generated automatically by the configuration tool.

Setup

It is recommended, but not required, to declare Tracks as an array. Starting at the zero index is also recommended.

// Instance declaration
Track           : ARRAY [0..GVL.NUM_TRACKS] OF Track;

Tracks then need to have an ID and OTCID assigned to them. Index 0 should use 0 for both values as this is a special case for the absolute hardware position that may be useful during startup or recovery of some track configurations.

OTCID is found in System > TcCOM Objects > XTS Processing Unit 1 > Track # and is labeled Object ID on the Object tab. Note that the value displayed uses the "0x" hex notation, but needs to be entered using "16#" hex notation in the code.

For simplicity the ID should match the array index. This application already includes code that assigns the ID to match the array index of the track.

        Track[0].OTCID := 0;                // special "absolute reference" case, not typically used
        Track[1].OTCID := 16#010100B0;  // default track used by code
        Track[2].OTCID := 16#010100D0;  // additional track
        // ... additional tracks

Use

Tracks are used in three ways in software:

Parameters to other objects
Managing movers on a track
Properties of a mover

Tracks as parameters

When configuring a Station, Zone or Position trigger a TrackID can be attached to each. If you are not using track management, a default TrackID is assigned to these objects that will allow them to work without explicitly assigning a TrackID.

Stations, Zones and Position Triggers will only return or act on movers that are assigned to the same track as the object's TrackId

// position trigger at 150.0 mm on track 2
PositionTrigger[1].Position := 150.0;
PositionTrigger[1].TrackId  := 2;

// Zone between 200.0 and 300.0 mm on track 3
Zone[1].StartPosition := 200.0;
Zone[1].EndPosition   := 200.0;
Zone[1].TrackId       := 3;

// Station at 250.0 mm on track 3
Station[1].Position := 250.0;
Station[1].TrackId  := 3;

Tracks managing movers

Tracks maintain a MoverList that can be used to track and query the movers on the track. See the MoverList object for complete details. Some common use cases are shown below

// move all movers on track to a station
// movers will queue at the station by using built-in collision avoidance
Track[1].CurrentMoverList.MoveAllToStation(Station[1]);

// find the mover closest to a fixed position on this track and set the velocity
Track[1].CurrentMoverList.GetMoverByLocation(0, 150.0, MC_Positive_Direction).SetVelocity(500.0);

// get the count of movers on this track
iMoverCount := Track[1].CurrentMoverCount;

Properties of a mover

Every mover is assigned to a track. Movers can only move to stations and positions on the track they are currently assigned to.

See the property Mover for additional information.

Mover Direction Considerations

When using tracks where some are closed loops (ovals) and others are not (spurs), it is important to pay attention to the direction mode of the mover with Mover.SetDirection(). By default this is set to mcDirectionPositive which works well for ovals and will automatically wrap positions (modulo) as the mover reaches the rollover point.

When a non-closed section of track is used (such as a rework spur), the mover commands Mover.MoveToPosition and Mover.MoveToStation as well as the related commands in a MoverList do not work with the default direction. When a mover is switched to a non-closed track, Mover.SetDirection(mcDirectionNonModulo) should also be called to set the mover's positioning to absolute along this portion of the track. Then when transitioning back to a closed section of track Mover.SetDirection(mcDirectionPositive) should be called to revert to the default modulo operation.

Methods

The methods listed below are used internally within the base code and should not be called directly by the user. They are shown for completeness.

RegisterMover

RegisterMover( NewMover : REFERENCE TO Mover )

This is used internally by Mover.TrackCyclic()

UnregisterAll

UnregisterAll( )

This is used internally by the Track Object

UnregisterMover

unRegisterMover( RemovingMover : REFERENCE TO Mover)

This is used internally by Mover.TrackCyclic()

Properties

CurrentMoverList

MoverList (Read Only)

Provides a MoverList object reference, containing all Movers that are currently assigned to this track. As a MoverList, methods are provided to command all movers as a group. See MoverList for more information

CurrentMoverCount

DINT (Read Only)

Returns the count of movers currently assigned to this track

Id

DINT

Stores the user-friendly numeric track identifier.

This property is read/write, but should only be written once during initialization and should not change during execution. It is provided for querying and comparing TrackIds between objects.

OTCID

OTCID

Stores the hardware id of the track object found in XTSProcessingUnit 1

This property is read/write, but should only be written once during initialization and should not change during execution. It is used internally by Mover.ActivateTrack()