DQMH was originally created and maintained by Delacor, with Fabiola De la Cueva being the chief architect.

In 2021, Delacor transferred all rights and responsibilities to the DQMH Consortium, LLC


The DQMH® Project Template is based on the NI Queued Message Handler Project Template (NI QMH).

The DQMH improves the NI QMH by:

  • providing safe, event-based message handling and scripting tools,which makes development easier

  • encouraging consistent style among different developers in the same project, which improves efficiency

The DQMH provides the greatest benefits in applications employing multiple modules running in parallel that communicate with each other. These different modules can run either with their front panel open or headless (with their front panel closed).

The DQMH can also be used for applications that have a single module in which a Tester has the capability of eavesdropping on the different DQMH events and messages (both in development mode and in an executable).

Each DQMH module has a structure similar to a NI Queued Message Handler module, and it has a Test DQMH Module (also known as the “Tester”) to help troubleshoot, debug, and eavesdrop on the communications between the DQMH Module and its calling code.

If the developer is creating an application that will employ multiple DQMH modules, the best place to start is with the Project Templates. This is done by clicking Create Project from the Getting Started Window in LabVIEW, and then clicking the DQMH Project Template.

If the developer is creating a single DQMH module that will be called by their existing code or used as a stand-alone application, open an existing project and use the Tools  DQMH Consortium  DQMH  Module  Add DQMH Module utility.

Starting with DQMH 4.1, there is also a Sample Project Template for the DQMH version of the Continuous Measurement and Logging (CML DQMH) Sample project. Create a copy of this sample project by clicking Create Project from the Getting Started Window in LabVIEW, and then clicking the CML DQMH Sample Project Template.

DQMH Background

Implementing communication between DQMH modules using events is based on the concepts presented by Justin Goeres during CLA Summit 2011 and NIWeek 2011 (more information here). The main modifications to Justin’s approach were (1) changing the nomenclature from Private/Public events to Request/Broadcast events, and (2) using the NI QMH as the basis for the modules instead of the JKI State Machine.

Documentation assumptions

This documentation assumes that you are familiar with Producer/Consumer design pattern and with the NI QMH Project Template. If you are not familiar with these topics, the NI QMH documentation can be found by clicking Create Project from the Getting Started Window in LabVIEW and then clicking the More Information link in the NI QMH project description. You can also create a project based on this template, which will include a copy of the documentation.

Use Cases


The first and foremost feature of the DQMH template is modularity, which can be thought of as dividing up a complex large-scale project into a series of simpler small-scale projects. Thus any good modularization framework should be based on a good small-scale template that should be usable by itself for a small-scale project.

It might seem "overkill" in a way to use a modular framework with only one module, but there are advantages, such as when project requirements unexpectedly grow and the project isn’t so small-scale anymore.


Reducing DQMH to that single aspect of modularity doesn’t do it justice, though. Even for stand-alone modules, you benefit from all the built-in features that come with DQMH: QMH pattern (no manual creation of loops or queues or events), scripting tools for adding functions, API testers for testing templates and more.


The DQMH template is useful for applications where multiple tasks occur in parallel, often at different rates. It is also useful when multiple instances of the same Front Panel are needed (this requires using a cloneable DQMH Module). For example, consider an application that controls a single temperature chamber and needs to log data from multiple units under test (UUTs). A cloneable DQMH Module would be used to implement a single UUT and a singleton DQMH Module would be used to implement the temperature chamber.

Singleton Design Pattern

The Tools  DQMH Consortium  DQMH  Module  Add New DQMH Module…​ utility can add individual DQMH Modules to existing projects. This is useful for applications where a continuous running process needs to be added and the rest of the code needs to communicate with this process. For example, consider an application where communication with a serial instrument needs to poll the serial port continuously waiting for a series of commands to be received. A singleton DQMH module could implement the communication with the instrument. The existing application could start this singleton DQMH Module and register to listen to the serial port commands. The Test DQMH Module could then be used to eavesdrop on the communication between the Singleton DQMH Module and the rest of the code as well as a vehicle to test the instrument connected to the serial port as well.

Stand-Alone Applications

The Tools  DQMH Consortium  DQMH  Module  Add New DQMH Module…​ utility can also be used to add a new DQMH module to a new project where the DQMH is intended to be the standalone application.


For existing applications, when adding features that will (or might) be used in other applications, refactoring your application and carving out said functionality into a DQMH module will provide the required level of modularity, i.e. the code to be shared is kept separate from the rest of the application, it is not depending on the rest of the application, and it provides a well-defined and documented API defining how it should be integrated into applications.

Due to the way that DQMH is designed, it does not dictate the architecture of the whole application. Developers can start out by adding a single module to their application, not having to migrate the complete application in one go.

Custom Controls

The DQMH template can also be used to create custom controls and indicators that will be embedded in a Subpanel in another VI. DQMH modules are a good alternative to XControls where the has the implementation for the control.

Design and Architectural Templating

Another use of the DQMH Module template is for teams with different levels of proficiency. The DQMH Module could be designed and implemented by one team member, and others with less LabVIEW familiarity could just call the DQMH Module API VIs in their code, without having to understand how the DQMH Module itself is implemented.


Here are some videos of presentations the Delacor team has given on real world examples using DQMH.

The following video is from a presentation we gave at NI Week 2017 where we created an application from scratch to executable in less than one hour.

Rapid Application Development with DQMH
You can find more details about this presentation at

The following video is from a presentation we gave at NI Week 2015. Starting at minute 29:55 the video describes how we modeled and implemented the application using DQMH modules.

Modular Approach for Production of Medicine