LogixNG Reference - Chapter 5

Action Descriptions

The action descriptions are grouped by the socket type and category.

since 5.1.3For, For each , If Then Else, Sequence, and Table: For each have been moved from the Common category to the Flow Control category. Call Module has been moved from the Other category to the Flow Control category.

Action dialogs

When the category and type has been selected, the detail action dialog will be displayed. The content of the dialog will vary depending on the category and type. The typical digital action item dialog is described below.

The dialog for adding and editing digital action items consists of an upper part that contains the item and the actions for that item. The lower part is common to all actions.

For some actions, for example Signal head, you need to first select the item and then you can select the action to do on that item. For example, for Signal head, you first select the signal head to act on and then you can select the appearence to set for that signal head.

Chapter 5 typical action

The Edit screen is the same except for the title, the Create button and the current content will be in the fields.

The left section is normally used to select the item, such as a turnout or a sensor. The right section is the action to be performed. The default mode will be to use the Direct tabs.

See Reference, Local Variable and Formula for details about the other tabs.

The lower section contains a standard set of items

Error Handling
If Use default is selected, the value in Preferences will be used. For other options see error handling.
Catch "Abort execution"
If the error handling (see previous) for any child node is set to Abort execution, a parent node should have this option checked. This lets the parent node handle the error.
Edit comment
Each action can have a comment. The comment dialog has a multiline text area. Click OK to save the comment.
Formula functions
These are explained in the Formula chapter.
Close the dialog without applying any changes.
Save the new action or the changes to an existing action.

Digital action :: Item

Chapter 5 digital action item list


Control the selected Audio item.


Clockupdated 4.99.7

Chapter 5 clock action

In addition to setting the time using a constant value, the other LogixNG modes can be used. For example, the new time can be in a memory variable which will be used to set the fast clock time.

Chapter 5 clock memory source

The Memory listen option can used to automatically update the fast clock time when the memory variable changes. This eliminates the need to have a separate expression to invoke the Set Fast Clock action.

Clock Ratesince 4.99.7

Chapter 5 clock rate action

The rate values can be whole numbers or decimals, such as .5. The rate values can also be supplied from the other LogixNG modes, such as a memory variable.


A Dispatcher train only exists from the time it is created until it is terminated. LogixNG uses the Dispatcher TrainInfo file to refer to a potential Dispatcher train. See the Saving and Retrieving Active Train Information section at Activate New Train. If the related train does not exist when the LogixNG action occurs, the action will be ignored. There will be no notification.

Enable/Disable Logix



Light intensity

The Light intensity action is an alternate method to set the Variable Light Intensity value. The standard method sets the value directly from the action using any of the standard input methods.

This action creates a child analog expression called Intensity. Analog expressions are normally used to create a dynamic values, such as random numbers. Using the sin() function along with the Minutes since midnight analog expression, it is possible to change light intensity based on the time of the day using the fast clock or the system clock.

Here is an example using the sin() function.

Chapter 5 intensity example

Local variable

Local variables are described in Chapter 8 - Local Variables.

Instead of specific actions, local variables use tabs to select the action.

Note: The Memory, Block and Reporter tabs have an option to listen to changes to their value.


Instead of specific actions, memory uses tabs to select the action.




The Reporter action is used to copy the report content to a memory variable or a LogixNG local variable. There are three kinds of information.

Note: The meaning of the reports and the state number are defined by originating hardware.

Request update of all sensorssince 5.1.6

Request the current status of sensors. The request can be limited to specific connections or all connections. The action depends on whether the connection supports sensor state requests.

Chapter 5 request sensor update



Chapter 5 digital action script


The delayed options are handled by Execute Delayed.

Signal head

Signal mast


Plays the specified sound file. Specify the sound file to play by entering its name in the field provided. Click the file selection button to bring up a file selection dialog to aid in finding the file. Navigate to your sound file, then click your sound file's name in the dialog and the name will be copied to the field.


The Throttle action controls a throttle.

Chapter 5 throttle dialog

The LogixNG throttle can use either the default throttle connection or an alternate throttle connection. The default connection is defined in Preferences ⇒ Defaults. If there is more than one connection, other connections might support a throttle.

Chapter 5 throttle action
Address — Analog Expression
Value between 1 and 9999.
Speed — Analog Expression
Value between 0.0 and 1.0.
Direction — Digital Expression
True for forward.
Function — Analog Expression
Value between 0 and 28.
FunctionOnOff — Digital Expression
True for function on

The analog expressions can be an analog memory expression or an analog constant expression. In the future, AnalogIO will also be available.

The digital expressions are either Always true or Always false .


The delayed options are handled by Execute Delayed.

Turnout, lock

Locks or unlocks a turnout. Select the name for the turnout, and choose the operation from the popup menu. Note: To control the type of turnout lock go to the Turnout Table and select the Lock Mode.


Digital action :: Common

Chapter 5 digital action common list

Digital Formulasince 4.25.8

The Digital Formula action provides the ability to create formulas that are not directly related to other items, such as sensors, which use the Formula tab.

The formula action is in particular useful when working with local variables. You can for example increase a local variable by the formula index++ or make some calculations, like turnout = name.substring(2) which removes the first two characters from the string.

The dialog for creating a Digital Formula consists of a single text field.

Chapter 5 digital formula dialog

See Chapter 9 - Formula for details.

Execute delayed

Delay the execution of the following action for a specified amount of time. This is the same as the Logix Delayed Set .... The main difference is that this can be used with any action, such as signals. The time delay units are milliseconds, seconds, minutes and hours.

The default mode is that once a timer starts, subsequent requests will be ignored. If Restart timer if already started is selected and a timer is already running, it will be canceled and started again. The subsequent action will be delayed until the timer finishes. If Use individual timers is selected, each request will be independent.

See Timeout for a conditional delayed execution.

Chapter 5 execute_delay


The Many action executes many child actions.

Read analog and set analog

Read an analog child expression and execute an analog child action.

Read string and set string

Read a string child expression and execute a string child action.


Timer has a number of actions, each executed after a period of time. The time to wait can be 0, which means the related action is executed immediately.


Start timer immediately on load
When selected, the timer steps will start when the LogixNG has been loaded. If this option is not selected, a Start expression will be used to start the timer steps when the expression becomes true.
Run timer continuously
If not selected, the timer will run one time and then stop. When selected, the timer steps will repeat. A Stop expression can be used to stop the timer steps when the expression becomes true. The Stop expression can use the same object, such as a sensor that starts the timer when active and then stops the timer when the sensor is inactive.
Start/Stop by Start expression
When selected, the timer will start when the Start expression becomes true and will stop when the Start expression becomes false. The Stop expression is ignored.
Combo Box
Select the time unit.
Chapter 5 timer dialog

If all times to wait are zero, the timer will automatically stop after executing all the actions once, even if it is set to run continuously. This is a safety feature to avoid locking up JMRI.

To add a socket for the Timer action, edit the Timer and click the Add timer button and a new socket will be added to the end. To remove a socket for the Timer action, edit the Timer and click the Remove timer button and the last socket will be removed. The socket can only be removed if there is no action connected to it.

This example shows using the Timer to implement a traffic light. Note: This example shows renaming the A1, A2, etc. sockets to meaningful names.

Chapter 5 timer example

Another example is using a Timer to blink a light. Create a Timer with a single socket and a Light action that toggles the light on/off. If you want different times for on and off, create a Timer with two sockets where the first socket turns the light on and the second socket turns the light off.

Digital action :: Flow Control since 5.1.3

Chapter 5 digital action flow control list


Breaks the execution of a For, For each or Table: For each action.

If Break happens in a Module and there is no loop in the Module itself, it breaks the loop in the calling ConditionalNG or Module.

Call module

See Chapter 10 - Modules for details.


Continues the execution of a For, For each or Table: For each action.

The current execution is aborted and the next loop is executed.

If Continue happens in a Module and there is no loop in the Module itself, it continues the loop in the calling ConditionalNG or Module.


Triggers an error. The user can enter an error message if desired.

This might be useful if a particular condition should never occur in the ConditionalNG or Module. In this case, the Error action can be used to alert the user.


Exits the execution of the ConditionalNG. If the Exit action is in a Module, the Module and the ConditionalNG will be exited.


For is a for-loop. It has four children.

When For is executed, the Init action is run once. After that, the While expression is evaluated. If the While returns true, the Do action is executed and at last the AfterEach action is executed. Then the process is repeated, except that the Init action is only executed once.

For eachsince 5.1.3

For each takes a Collection, a Map or a Manager as parameter and loops thru all the items. For maps, each item is a Map.Entry. Use getKey() and getValue() to get the key and the value of each item in the map. If the parameter is a manager, the method getNamedBeanSet() is called to get all the named beans in the manager.

Each item is placed in a specified local variable. The action is then invoked for each item.

The following example sets all of the sensors to Inactive.

Chapter 5 for each

For another example, see Listen on beans - Local variable.

If Then Else

Reads a digital child expression and if the answer is true it executes the then child action, else it executes the else child action.

Chapter 5 if then else dialog

There are two settings that control the if-then-else processing.

When is the If-Then-Else executed

Execute on change
Executes the Then or the Else action only when the If expression has changed from True to False, or from False to True. Note that the expression is assumed to be changed whenever the LogixNG is first enabled (including when the xml data file is loaded with "enabled" checked). In the simple example below, Light IL2 will be set "on" when the LogixNG is first enabled (Sensor IS1 status is "unknown"). When the sensor is changed to "inactive" the lights will not change. When the sensor is then changed to "active," the Light IL1 will also go "on".
Always execute
Executes the Then or the Else action every time the If Then Else action is executed, regardless of whether the expression has changed value.

How is the If expression evaluatedsince 5.1.6

Evaluate all expressions
All of the expression elements are evaluated to determine the true/false state of the If.
Evaluate needed expressions
Evaluate each expression element until true/false is determined. An And series ends when an element is false. An Or series ends when an element is true.
Chapter 5 if then else
Else_Ifsince 5.1.3

The Else_If option provides a compact method to collapse a repetitive nested If-Then-Else tree.

To create a new Else_If expression/action pair, right click on the Else row and select Insert new socket before.

Chapter 5 else if insert

A new expression/action pair will be added before the Else.

Chapter 5 else if items

Here is simple example of using LogixNG to create signal logic.

Chapter 5 else if example

The example first checks the turnout block. If that is ok, it then checks the route to each possible destination signal based on the turnout state. If nothing works, it sets the signal to display Stop.

Chapter 5 else if sample


Returns from the Module or the ConditionalNG.

If Return is in a ConditionalNG, it's the same as Exit. But if it's in a Module, it only exits the Module, not the ConditionalNG.

Run oncesince 5.3.1

Run the assigned action only one time during a JMRI session.

The assigned action will be the Many action if there is more than one action to be performed. This provides an alternate method compared to Trigger once for startup initialization.


The Sequence action executes a series of action/expression pairs. For each pair, the action will be performed and then the expression will wait until it becomes true. When it is true, the next action/expression pair will be started.

Chapter 5 sequence options


When a sequence action is added, it has connections for Start, Stop and Reset expressions.

Chapter 5 sequence action

Table: For each

See Chapter 11 - Table Actions for details on table actions.

Digital action :: Display

Chapter 5 digital action display list

Icon/Label on panel

Disable/Enable/Hide/Show an icon or label on a specific panel.

Turnout on LayoutPanelsince 5.3.1

Disable/Enable a turnout item on a specific Layout Editor panel. A separate action is needed since the turnout image on a Layout Editor panel is not an icon.

Chapter 5 layout turnout action

The action applies to a single turnout item. To change all of the turnouts, use a For each action.

Chapter 5 layout turnout for each

Digital action :: MQTT since 4.99.7

Chapter 5 digital action mqtt list


This action publishes a message. Both the topic and the message can be entered directly in the action or indirectly using a local variable or a memory.

Chapter 5 digital action mqtt publish


This action subscribes to a topic. When someone publishes a message, this action triggers the execution of the CondtionalNG. It can also optionally put the topic and the message into local variables. The topic can use wildcard, like loco/# where # is the wildcard.

Chapter 5 digital action mqtt subscribe

Digital action :: LocoNet

Chapter 5 digital action loconet list

Clear loconet slots

This action clears the slot status in the command station if you are using LocoNet.

Set speed to zero for all loco slotssince 5.1.6

Sets the speed of the Digitrax command station slots to zero.

Update loconet slots

This action forces an update of the LocoNet slot status in JMRI.

Digital action :: Other

Chapter 5 digital action other list

Create beans from tablesince 5.1.6

See Chapter 11 - Table Actions for details.

Find table row or columnsince 5.1.6

See Chapter 11 - Table Actions for details.

Listen on beans

See Chapter 7 - Listen on beans for details.

Listen on beans - Local variablesince 5.1.3

Add a listener to the bean referenced by a local variable. The local variable can have either the system name, the user name or the bean itself. The Execute socket provides the logic that will be executed when an event occurs.

Chapter 5 listen bean local variable

The bean Type and the listen local variable name are required. The other local variables are optional.

This action is especially useful together with the action For each. This sample listens for sensor state changes and prints a message on the system console.

Chapter 5 listen bean local variable sample

Listen on beans - Table

See Chapter 11 - Table Actions for details.

Log data

While developing a ConditionalNG, it can be helpful to see field content, make note of the location within the tree, etc. Adding the Log data type in the Other category will display a dialog to configure the Log data options.

Another approach for displaying data is to use the Show dialog action.

Select either or both Log options

Chapter 5 action log data

There are three format types.

Chapter 5 log data format

The table lists the data sources for the comma separated and and string format options.

Click on the Add button to add an entry to the table. Select the source type and add the name or a reference in the Data field.

Chapter 5 log data sources

This example uses the string.format option to combine text with the contents of two memory variables.

Chapter 5 log data sample

Log local variables

See Chapter 8 - Debugging local variables for details.


LogixNG has an action called Logix that emulates how JMRI Logix works. The action Logix has one expression and a number of boolean actions. A boolean action is an action that takes a boolean value (true/false) and then decides what to do. The action Logix was added mainly to support import of JMRI Logix to LogixNG.

Show dialogsince 4.25.8

The Show dialog action displays a window that can be used to provide notification of an event that has occurred or needs to be handled. It can also be used to request whether an action should be performed by the LogixNG.

Normally, warnings and such can be handled by displaying a message in the system console. The dialog is useful when an immediate notification is needed.

The Show dialog definition is similar to the Log data definition. See Log data for details on formating and including variables.

Chapter 5 show dialog dialog

Additional Features:

One or more buttons can be included in the dialog. At least one button must be selected.
A dialog can be modal or non-modal. Modal means that the dialog window remains above any other window and the user cannot do anything in any other JMRI window until it is closed.
The multiline option enables the ability to have multiple lines displayed by the dialog. To get a new line, use the HTML <br> tag.
Selected button
If a predefined local variable is supplied, the selected button number is copied to the local variable. The button numbers are shown next to the button text in the button selection section.
Input stringsince 4.99.1
If a predefined local variable is supplied, a text input field is included. The current value of the variable will be displayed in the text input field. When the dialog is closed using one of the buttons, the value in the input field will be copied to the local variable.

Note: When the dialog is displayed, the rest of the conditional continues to run. In the first example, the A3 action will execute while the dialog is displayed.

After the dialog action has been created, two new rows are added. These are both optional and can be left empty.

Chapter 5 show dialog validate execute
The Validate expression can be used to check for valid input when using an input local variable. If the expression is false, the dialog will remain open until the expression is true. The close button on the window can be used to bypass validation and execution. If the expression is true or no expression was defined, the Execute action will run.
The Execute action is run when the validation expression is true or if one was not defined. A common use is handling a multiple button dialog that has the selected button local variable.
Sample dialog with button checking
Chapter 5 show dialog yes no
Chapter 5 show dialog button process
Sample multiline dialog with string.format
Chapter 5 show dialog multiline
Chapter 5 show dialog multiline sample
Sample input dialog with validation using a digital formula
Chapter 5 show dialog input sample
Chapter 5 show dialog iniput code

Shut down tasksince 5.1.6

Create a task that will run before JMRI shutdown occurs.

Chapter 5 shutdown task

If the Expression is empty or returns true, the Action will be executed before JMRI shutdown continues. If the Expression returns false, the JMRI shutdown process is stopped.


The ShutdownComputer action can either shutdown or restart the computer, or shutdown or restart JMRI.

Simulate turnout feedbacksince 5.1.3

The Simulate turnout feedback action is used to make turnouts behave as expected when using a simulated layout connection. The feedback delay is 3 seconds.

The following feedback modes are supported. The available modes depend on the layout connection type.

The Connection name expression can be used to create a LogixNG that automatically enables turnout feedback when using a simulated layout connection.

Timeoutsince 4.25.8

The Timeout action is used to execute a default action if an expression is not true within the specified time internval.

The Timeout action dialog is similar to the Execute Delayed dialog. The Timeout configuration also requires an expression. If the expression is true before the time expires, the action is not executed.

delayed vs timeout

Web browser

The Web Browser action opens a web page in the default web browser.

web browser

The URL is supplied using a string expression.

Web requestsince 5.3.5

The Web Request action sends a GET or POST request to a web server. When the request has completed, the Execute action is performed.

web request execute

The request information is defined using the Web Request dialog. The dialog settings will depend on the web server application requirements.

web request dialog

Note: The LogixNG_WebRequest_Test.php portion of the URL is a sample application.

Top Level Tabs

The URL contains the address of the web server. For GET requests, parameters can be added to the URL using the ?name=value&name2=value2 format. Parameters in the Parameter section are also added to the GET request URL.

For POST requests, the parameters are defined in the Parameters section.


Specify the character set to used for the application.

web request character set
Request method

Specify the request method to used for the application.

web request method
User agent

Specify the user agent to be used for the request. The default is Mozilla/5.0 .

Local Variables
Local variable for response code

The value of the local variable will be the numeric response code from the server. For successful requests, the value will be 200.

Local variable for reply content

The value of the local variable will be the content returned from the server. Sometimes the content will have error messages detected by the server or the application.

Local variable for cookies

The value of the local variable will have a copy of the current cookie. If the cookie needs to be shared by different ConditionalNGs, use a global variable.


There are two example files included in the JMRI distribution. They are located at help/en/html/tools/logixng/reference/WebRequestExample


This is a layout config xml file that has sample table entries.


This is a PHP program that acts as a web based application. This needs to be installed in a web server that has been configured to run PHP programs. The source code can be downloaded from GitHub.

Digital boolean action :: Common

To make import from Logix to LogixNG easier, LogixNG has a special action, Logix, that works similar to a Conditional in Logix. The LogixNG Logix action has a digital expression socket and a digital boolean action socket. The usual setup in LogixNG is a Logix action with a Many child with a number of OnChange children.

Chapter 5 digital boolean action common list


The Many action is used together with the Logix action to let the Logix action have more than one action child.

On change

This action is used together with the LogixNG Logix action and gives you the option to decide if the child action should be executed. The options are:

Analog action :: Item

Chapter 5 analog action item list

Light intensity

Sets the intensity of the selected variable light to an analog value.


Sets a memory to an analog value.

Analog action :: Common

Chapter 5 analog action common list


Sets the value of many analog actions.

String action :: Item

Chapter 5 string action item list


Sets a memory to a string value.


The StringIO sets the string of a StringIO. There is currently one StringIO that can be used with this action: The LocoNet "LCThrottles" StringIO that sends a message to the LocoNet throttles.

String action :: Common

Chapter 5 string action common list


Sets the value of many string actions.

Chapter 6 - Expression Descriptions

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