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Warrants

A Warrant is a collection of information sufficient to run an automated train. It will set the turnouts for a specified route and detect whether there are any other trains occupying it. A JMRI Warrant is suggestive of what a warrant does on a prototype railroad, but there is no intention to replicate any particular railroad's mode of operation.

Warrants depend on having an accurate description of the layout in terms of OBlocks, Portals and OPaths. These elememts are created using the Occupancy Block Tables that you will find under the Tools menu in the PanelPro window. Their definitions and how to use them are described in The Occupancy Block Tables.

It may be easier to define OBlocks, Portals and OPaths using the Circuit Builder tool found in the Control Panel Editor. The Circuit Builder will also convert the track segments and turnout icons of your layout to Indicator Track and Indicator Turnout icons. These icons display by color the status of the OBlock they represent - whether the track circuit of the OBlock is occupied or unoccupied, whether a warrant has allocated it or whether a train under warrant currently is proceeding over the circuit. The Circuit Builder is accessed under the File menu of the Control Panel Editor. Choose the "Change View to Circuit Builder" menu item. Instructions for use are found in The Circuit Builder.

Creating a Warrant

In order to create a Warrant you must first have created two or more OBlocks. These blocks don't have to be fully defined, but their existence indicates that you are interested in using Warrants. When two or more OBlocks exist the Panel Editor will display a Warrants menu with three menu items. Otherwise, this menu is not displayed. The Warrant menu items are:

Functions of a Warrant

Creating Routes

Routes are created from the Define Route tab.

A warrant route is a series of block paths linked together so a train may travel over it. A warrant route is created by first choosing an origin block, a starting path and a portal to exit the orginating block. Then, destination block is chosen and a path on which to end the route. Blocks are chosen either by typing in the block name or dragging it from a displayed OBlock table. A computer algorithm will determine all the intermediate blocks and paths to make the route.

The origin block is obviously where a train given this route will start and the starting path within the origin block is the track it is on - e.g. "Departure Track #3". Choosing the portal of the path where the train should exit, determines the direction of the train on the route. From here on, the computer algorithm will find portals, paths and blocks to take the train to the destination block and path - e.g. "Arrival Track #1" in the destination block.

There may be more than one way to get from the origin track to the destination track. The computer presents you with a list of all the routes it finds - some of these may be quite lengthy. You may review and choose the route you want to use from the list. If the list is too lengthy, you may restrict the number of routes found by specifying an intermediate via block and path that must be included in the route. The computer will re-calculate the route with this restriction and present you only with routes through the specified "Via" block and path. Creating and Editing Warrants. has more information about this.

The computer may not find a route from the origin track to the destination track that you believe is there. When this occurs, you may request the computer to display the routes the algorithm has attempted. As you trace the attempted routes you may find that you have forgotten to enter a path or miss-labeled the correct portal to a path. (or, heaven forbid! found a bug.)

When you are satisfied with the route, select the Record/Playback Script tab.

Tables on the Record/Playback Script Tab

Radio buttons on this tab allow you to select either the Route Table or the Throttle Command Table. The Route Table shows the track circuits (OBlock, Portals and Paths) the warrant defines. The Throttle Command Table shows each throttle command that is recorded in "Learn Mode". After recording, the table can be edited - changing values, inserting or deleting rows. Also, a sensor can be added to the commands to trigger an external event.

Choosing a Train

Inside the Choose Engine Consist box you will find a drop dowm 'combo box' labeled Engine Roster that displays all the trains listed in the Roster. Selecting one will assign a train to the warrant.

If you do not have a Roster defined then you may enter a locomotive's DCC address in the Address text field and a train responding to this address can be 'taught', the commands it should issue, and later, 'run'.

The Train Name test field is used to enter the name of train when the commands are played back. This name will appear in a Loco Marker icon that is displayed in indicator track as the train travels along the warrant route.

Creating and Editing Warrants. has more information about this.

Learn Mode Throttle

If a train has been assigned, that is, has a valid train Id or valid DCC address in the warrant, then a throttle can be aquired by pressing the Start button. This throttle will operate the acquired train and all the throttle commands will be recorded until the Stop button is pressed. Creating and Editing Warrants. has more information about this.

Recorded Throttle Commands

The throttle commands recorded in Learn Mode can be edited, however, caution should be taken to only make modest changes since new commands when executed in playback could cause dramatic events. It may be wiser to re-record the commands in a new Learn Mode session if major changes are made. Creating and Editing Warrants. has more information about this.

Running Automated Trains

The recorded throttle commands can be played back to run the train. When in Run Mode, additional control of the train can done through three choices: Halt, Resume and Abort. As suggested by the names, these command stop a running automated train, restart it or stop the train and abort the remaining throttle commands.

Although there are separate operations to reserve a warrant route (Allocate) and set turnouts and signals (Set Route) these operations do not have to be done to run an automated train. A Run operation can begin without them. The train will seek allocation and set turnouts and signals as it proceeds on the route. When confronted with an occupied block, the train will stop and wait until the block clears. When the next block is clear but the block beyond the next block is occupied, the train will approach at reduced speed. An automated train will attempt to secure allocation of the next two blocks each time it enters a block. Creating and Editing Warrants. has more information about this.

Editing Throttle Commands

The recorded throttle commands execute according to the elapased time between commands. The elapsed time (ET column) may be modified and even the command may be changed. Rows may be deleted and additional rows added.

Changing the consist of a train or perhaps even a temperature change between recording and playback, may result in the train not performing a throttle command at the same place on the layout each time. The Throttle Adjustment text field can be used to modify the throttle setting by a fixed ratio for all speed commands. - or individual commands may have their throttle setting or elapsed time value changed.

The "NOOP" commands with value "Enter Block" should not be removed. These rows are used to synchronize the automatic running of a train to the recorded elapsed time in the block, by either extending the elapsed time if the train has arrived too soon or shortening the elapsed time of the following commands if it arrived too late.

The run protection discussed in the previous section and synchronizing commands depends on reliable occupancy detection. If the layout is prone to have spurious false detection signals, then automated running will be unsatisfactory - trains may wait indefinitely for phantom trains to release occupancy or run indefinitely by not receiving a synchronizing signal. The train can be run using the elapsed times between commands only and skip the block protection mentioned above i.e. "Run with Blocks Dark".

Using the Warrant List

The Warrant List menu item opens the Warrant Table. Each row is a warrant that has been created. Warrant routes can be reserved, the turnouts and signals set and trains run and controlled using the columns in the table.

Columns in the Warrant Table

Using Warrants in Logix

Several of the operations that can be done from the Warrant List and Warrant Editing frame can be done with Logix Conditionals. You may design and implement a dispatcher's panel using the Warrant state variables and actions found in Logix.

Warrant State Variables

When a warrant has been allocated or is in effect, the following state variables can be tested in a Logix conditional.

Warrant Actions