Case Studies

Relay Multiplexer Module

Relay Multiplexer Module with .NET Driver Library

Posted in Automotive, Battery Pack Test Systems, Circuit Design, Embedded Development & Programming, Energy and Utilities, Green Technology, LabVIEW, Product Development, Test & Measurement Automation, Test Stand


DMC delivered a low cost, high density Relay Multiplexer Module for a high channel count test application for a client in the performance racing automotive sector.  DMC provided the client with multiple methods for controlling and operating the device, including a soft front panel interface, a library of LabVIEW drivers, and a DLL package of .NET drivers.

Soft Front Panel - Control Server

Soft Front Panel - Control Server

Client DUT Connections and Meas Lines

Client DUT Connections and Meas Lines


For this project, DMC leveraged past experience in designing measurement multiplexer systems for similar applications.  By building upon an existing foundation of software control functions and hardware designs, DMC was able to implement a multiplexer module tailored to the clients specific needs with very minimal development time.   DMC customized aspects of the system such as channel counts and DUT pin-out connections to meet the customers testing requirements, but utilized a proven core architecture for the multiplexer module  to deliver optimal performance and reliability.

The system also featured a high isolation voltage of 1000 V between all multiplexed channels as required by unique aspects of the client's testing requirements.

The client wished to integrate the relay multiplexer module into an existing test platform that ran off of a custom Microsoft .NET Test Control Application that they had developed. To make this integration process as seamless and straightforward as possible, DMC implemented a set of .NET drivers to enable control of the multiplexer directly from a .NET application.  This DLL included a library of simple function calls for direct control of all multiplexer operations and provided command acknowledgement and exception handling capabilities.

DMC's customizable relay multiplexing systems can similarly be controlled over a wide variety of interfaces including Serial (RS232 or RS485), Ethernet (TCP/IP or UDP), and CAN.

For easy transparency and visualization of multiplexer module operation, the user has the option of viewing the multiplexer system state through the front panel of the control server application (see photo).  This provides an abstracted depiction of the actual state of all 300+ relays in the multiplexer and active measurement connections that is updated in real time during multiplexer operation.

Customer Benefits

  • Low Cost: Significant cost savings over hardware costs for off the shelf multiplexer hardware for equivalent channel counts
  • Multi-Interface Support:  Custom drivers were implemented to enable control of the module from a .NET application, the Client's preferred test development platform
  • Simple Maintainability: Relay Multiplexer Module includes smart Self Diagnostic routine capable of rapidly identifying any damaged relay components
  • Easy Integration: Thorough documentation of the multiplexer module enabled client to quickly integrate it into their existing platform with no issues


  • Altium Designer for custom multiplexer PCB design and fabrication
  • LabVIEW for multiplexer module control server application
  • National Instruments M-Series PXI DAQ module and NI DAQmx for high speed relay control
  • Microsoft .NET for multiplexer module control via driver DLL