I/P Transducers

Our client, an industry leader in analytical instruments and scientific equipment, manufactures solid state current-to-pressure (I/P) transducers to provide reliable electronic input signal conversion in the most demanding industrial environments.

These rugged and compact I/P transducers use minimal electrical energy and air consumption to convert an electronic input signal to a proportional pneumatic output signal.  When assembled, the individual transducer electronics must be precisely calibrated and tested to ensure accurate conversion across the entire operating pressure range.

Our client’s existing I/P Calibration Test System had been in continuous operation for nearly four decades, and was long overdue for an upgrade.  The station “computer” was a legacy HP-85, introduced by HP in 1983, and obsoleted in November of 1987.  It was a struggle for our client to keep the calibration system operational, including maintaining a redundant back up HP-85 computer, sourcing replacement components, and making repairs on a machine more suitable for a computer museum.

The vintage HP-85 is a fully integrated desktop computer with full-size keyboard, built-in 6” CRT display, tape drive, and thermal printer.  Its 8-bit CPU runs at a blistering 613kHz (!), and performs real number arithmetic in BCD (binary coded decimal) instead of binary for accuracy to 12 significant decimal digits.  It had 64k of user program RAM, and a plug-in ROM drawer that contained the HP Basic operating system.

The existing legacy HP Basic calibration software presented an interesting challenge.  Eagle Lake architects had to review, analyze, and reverse-engineer the legacy hardware I/O and software design to ensure that the replacement LabVIEW software replicated the existing stimulus, measurement, calibration approach, and calculations for linearity, hysteresis and percent error results. 

The new system integrates the station pneumatics, NI cDAQ data acquisition electronics, modern PC, pressure and flow sensors, reference manometer, computer monitor, task lighting, keyboard drawer, and pneumatic test fixture into a standalone work station suitable for daily production work.

For the pneumatics and mechanical design, Eagle Lake hired Exacting Engineering of Cambridge, MA to provide the mechanical engineering design, fabrication, assembly, debug & systems integration.

Eagle Lake provided the system architecture, electrical, and software design.  Together we tested, integrated, calibrated, demonstrated and delivered the new I/P calibration test system to the client on budget and ahead of schedule.