An electronic unit denoted the Miniature Intelligent Sensor Module performs sensor signal conditioning functions and local processing of sensor data. The unit includes four channels of analog input/output circuitry, a processor, volatile and nonvolatile memory, and two Ethernet communication ports, all housed in a weathertight enclosure. The unit accepts AC or DC power. The analog inputs provide programmable gain, offset, and filtering as well as shunt calibration and auto-zeroing. Analog outputs include sine, square, and triangular waves having programmable frequencies and amplitudes, as well as programmable amplitude DC.
One innovative aspect of the design of this unit is the integration of a relatively powerful processor and large amount of memory along with the sensor-signal-conditioning circuitry so that sophisticated computer programs can be used to acquire and analyze sensor data and estimate and track the "health" of the overall sensor-data-acquisition system of which the unit is a part. The unit includes calibration, zeroing, and signal feedback circuitry to facilitate health monitoring. The processor is also integrated with programmable logic circuitry in such a manner as to simplify and enhance acquisition of data and generation of analog outputs.
A notable unique feature of the unit is a cold-junction compensation circuit in the back shell of a sensor connector. This circuit makes it possible to use Ktype thermocouples without compromising a housing seal.
Replicas of this unit may prove useful in industrial and manufacturing settings — especially in such large outdoor facilities as refineries. Two features can be expected to simplify installation: the weathertight housings should make it possible to mount the units near sensors, and the Ethernet communication capability of the units should facilitate establishment of communication connections for the units.
This work was done by Russell S. Beech of NVE Corp. for Stennis Space Center.
Inquiries concerning rights for the commercial use of this invention should be addressed to:
11409 Valley View Road
Eden Prairie, MN 55344-3617
Refer to SSC-00246, volume and number of this NASA Tech Briefs issue, and the page number.