OPC DA Connect

OPC Client Communication Toolset for NI TestStand™

MESULOG OPC DA Connect provides a set of high-level custom TestStand steps that help
your test benches to communicate easily with OPC servers.

OPC DA Connect is a NI TestStand Product Partner

Figure 1 : Connectez NI TestStand à vos automates programmables...

Figure 1 : Connect TestStand to all of your programmable automation controller...

OPC DA Connect:

  • Fully integrates with TestStand. You can use its customisable steps to create test sequences in your application.
  • Features step parameters that work with all TestStand variables to give you total flexibility in creating custom sequences.
  • Facilitates the readability and scalability of the sequences you create because each of its steps provides a self-description containing its main parameters.
  • Allows you to navigate through your network to easily select the I/O available on your OPC servers.
  • Optimises the access time to OPC items during read or write operations.
  • Works with OPC Data Access 2.0.
  • Works with the NI Shared Variable Engine.
  • Allows simultaneous connection to multiple OPC servers.
  • Costs nothing to deploy.

Ease of use

With full TestStand integration, OPC DA Connect helps you increase productivity during your test application development by facilitating interconnection with your OPC servers.

OPC DA Connect allows:

  • Easy step setup with built-in configuration windows
  • Step customisation via the TestStand Expression Browser
  • Quick access to all steps from a provided step palette in the Sequence Editor

Configure a Step
Each OPC DA Connect step has a specific configuration window. A step parameter can be a constant or a TestStand variable (see Figure 2). With the integration of the Expression Browser inside each configuration window, you can easily select or edit a variable for the Step Configuration.

Figure 2 : Fenêtre de configuration d'un pas OPC DA Connect

Figure 2: Configuration window of an OPC DA Connect Step

Built-in help
Each window includes a button to access the built-in help, which gives you first-level support in using OPC DA Connect.

Readability of the sequence file
The description field of each OPC DA Connect step is self-constructed based on the configuration of the step. Because of this, your sequence file is more readable and easily editable (see Figure 3).

Figure 3 : Auto-description des pas dans l'éditeur de séquence

Figure 3: Self-description of steps in the sequence editor

Custom palette
OPC DA Connect steps are listed in a dedicated palette accessible directly from the TestStand Sequence Editor. The following steps are provided:

  • Open: Connect to an OPC Server and create a communication thread (place this step in the Setup part of the sequence).
  • Read: Perform a read access to an OPC Variable.
  • Write: Perform a write access to an OPC Variable.
  • Close: Close the communication thread and disconnect from an OPC Server (place this step in the Cleanup part of the sequence).
Figure 4 : Palette OPC DA Connect de pas personnalisés

OPC Variables

OPC DA Connect allows multiple connections to different OPC servers. To simplify the selection of servers and variables, OPC DA Connect features two browsers: OPC Server and OPC Variable.

OPC Server Browser
Quickly visualise and select all available OPC servers through the OPC Server browser, which lists all reachable servers on your machine or over the network

Figure 5 : Fenêtre de navigation des serveurs OPC

Figure 4: OPC Server Browser Window

OPC Variable Browser
Once you have selected a server, designate the variable to read or write. The variables data type can be String, Boolean, or Numeric.

Figure 6 : Fenêtre de navigation des variables

Figure 5: OPC Variable Browser Window

Note also that:

  • The variable path is self-constructed from the OPC item selection.
  • You can copy/paste your steps and directly edit the name of the variable to configure different steps easily.

You can also use TestStand variables or expressions dynamically evaluated for the OPC variables or server used in your test sequence.


  • OPC DA Connect used an optimised communication process to reduce the read/write access time of an OPC Item.
  • You can save time during development by using a ready-to-use and fully customisable product.
  • Tuning your test sequence is simpler with the automatic integration in the NI TestStand Report of all the parameters and results of each step, including Timestamp and Quality Code.



OPC DA Connect includes a free Execution License. This means you can run the OPC DA Connect steps present in your test sequences without license activation.

However, to take advantage of the editing capabilities of OPC DA Connect steps, you need a OPC DA Connect Devlopment License.

A trial version of OPC DA Connect allows testing editing features. This trial version is fully functional for 10 minutes after starting the TestStand engine and for 30 days.

An item 'OPC DA Connect' is added to the TestStand's Tools menu and can be used to trigger the evaluation period or activate your development license


OPC DA Connect Execution LicenseFree
OPC DA Connect Development License 450 €


Online Help

OPC DA Connect help is available online

  Centr'Alp - Parc du Pommarin
Bâtiment C
137, rue de Mayoussard
38430 MOIRANS France