DMC recently integrated a Fluke 726 handheld multifunction calibrator into a turnkey automated test system. The test system incorporated a large switching matrix connected to multiple test instrumentation hardware components to perform a variety of automated test sequences on our client's test article.
Multifunction process calibrators are powerful and unique instruments capable of sourcing and measuring more signal types than a multimeter including thermocouple signals, RTD signals, and low current transmitter signals. The Fluke 726 that ourcustomer requested does not have a benchtop or PXI chassis-mountable form factor which made integration a challenge.
Advantages of the Fluke 726
Though handheld devices are awkward to integrate in otherwise very standardized server racks, the Fluke 726 offered our client several advantages over a collection of other, similar rack-mounted devices. The Fluke 726 is already widely used at our customer’s facility, meaning that a calibrated supply of these calibrators is readily available to swap into the test system if needed by the end user. Additionally, keeping the existing equipment allows us to implement the customer’s exact test steps without needing to adapt their tests for new equipment, allowing an easy one-to-one comparison of automated and manual test results.
Power
Unlike most of our automated test equipment, the Fluke 726 is powered with four AA batteries, which posed a unique challenge to integrating it in our turnkey system where most devices run on 120V or 240V power. We opted to integrate a battery eliminator to allow us to power the calibrator with the rest of our system and minimize the downtime of constantly changing the batteries. Our custom-built Power Distribution Unit converts facility power into different voltages for our test instrumentation and sends power to our battery eliminator, allowing the Fluke 726 to power up with the rest of our system and integrate into our emergency-stop safety circuit.
Automated Control
The Fluke 726 is controllable with VISA commands via an RS-232 serial interface. This allowed us to integrate control of the Fluke 726 into our custom application by wrapping these VISA commands into LabVIEW drivers and creating APIs for each of our customer’s desired functions, such as simulating a thermocouple voltage, measuring an RTD signal, etc. These functions are then available to the user for manual control of the device through our application.
Taking it one step further, these LabVIEW drivers are also wrapped into custom TestStand steps which allows us to integrate control of the calibrator into automated test routines and log measurements from the calibrator.
Takeaways
Integrating handheld devices rather than rack-mounted devices is not commonly needed in automated test equipment design, but when it provides value to an end user it can be incorporated as described in this article. Though it was contrary to our usual instrument integration, DMC was prepared to tackle the challenge and created a robust solution that satisfied our customer’s needs and can be propagated to future projects where customers have similar requirements.
Learn more about DMC's Test and Measurement Automation expertise and contact us for your next project.