Virtual Wiring Harness Overview

Earlier, under Architectural Concepts we introduced the idea of a Virtual Wiring Harness.  Here we explain how it is used in the context of the MxVDev test environment.

Consider the case where you want to start creating test cases before there is anything to test (no model, no C code, and no electronics). And because we have nothing to connect to, there will be no Virtual Wiring Harness at this stage either.  We need to start creating the set of Signals that are available to the tester in MxVDev.  This set of Signals will be the Signals that pass between MxVDev and the Virtual Wiring Harness. So at the early stages of a project, making entries in the Signal Dictionary is actually setting up the configuration of the Project Connector.

In the simplest case, these Signals match one-to-one with the I/O of the SUT (all of the Signal units and scaling match also).  In this case, the Virtual Wiring Harness is trivial, like a ribbon cable (wiring harness) with a connector at each end,.  The connector at the MxVDev end of the Harness is called the Project Connector.  The connector between the wiring harness and the SUT is called the SUT Connector.

When a preliminary Project Connector is defined, you are ready to create the Virtual Wiring Harness using MxTransIt. The Virtual Wiring Harness is an interconnected graph of Transforms. Signals defined in MxVDev should have a corresponding port in the Harness.

You use the Connections dialog to define the connectivity between the Project Connector and the SUT Connector, or in other words, between MxVDev and the SUT in MxTransIt. You can also use the Connections dialog to add signals defined in MxTransIt to the MxVDev Signal Dictionary.

The Virtual Wiring Harness provides the mapping to connect the idealized test cases in MxVDev with the SUT.  In the simplest case, the MxVDev signal names match one-to-one with the I/O of the SUT, and all of the Signal units and scalings match also. In this case the Virtual Wiring Harness is trivial (like a ribbon cable with a connector at each end). This connection point between MxVDev and the Harness is called the Project Connector.  The connection point between the Harness and the SUT is called the SUT Connector:

In some cases, the Harness itself may be the SUT. The Getting Started with a C# Snippet project is a simple example of using a Transform in the Harness as the SUT.

For SIL testing with the MxVMC, the Harness is connected to a VMC, which is the SUT.

For MIL testing, the SUT is a Simulink model, and the Harness connects to it using an S-Function Connector Transform.

For HIL testing, the Harness connects to an external SUT using Connector Transforms.

Connecting MxVDev to the Virtual Wiring Harness

To establish a connection between MxVDev and your Virtual Wiring Harness,  use the Connecting Signals dialog. In the simplest case, the dialog connects the signals automatically after the Harness is changed in MxTransIt.

If your SUT has a single VMC, you can also use Data Routing in the Signal Dictionary.

Related Topics:

MxTransIt Overview

Connecting Signals

Disconnect/Connect Harness