LVDT comes with digital output as standard

Schaevitz Sensors has launched what it claims to be the first totally self-contained and packaged digital-output LVDT.

Schaevitz Sensors, a division of Measurement Specialties, has launched what it claims to be the first totally self-contained and packaged digital-output LVDT.

The new model HC485 is the first sensor introduction in Schaevitz' new line of digital LVDTs.

Eliminating the need for expensive and error-prone analogue-to-digital conversion, the new HC 485's direct digital output allows traceable measurement without the need for complicated on-site calibration and setup between the sensor and control system.

Using factory computed conversion tables, analogue output is scaled into calibrated engineering units (inches and mm) by an internal microprocessor.

A certificate of calibration is shipped with every sensor.

The need for an analogue/digital convertor has also been eliminated, reducing overall system cost and complexity.

Operating on an 8.5 to 30V DC supply, the output is on a two-wire addressable RS485 loop.

Linearity is better than 0.25% with minimum 15bit resolution.

HC485 Series LVDTs use the industry standard RS485 interface with ModBus RTU and ASCII protocols, enabling up to 32 devices to communicate on a single pair of wires.

The HC485 offers the benefits of repeatability, resolution and noncontact ruggedness common to all LVDTs.

Concerns regarding cable length, calibration and re-calibrations are eliminated with the use of engineering units, enabling the sensor to provide previously unattainable levels of interchangeability with analogue LVDTs.

Max, min and TIR functions are stored in memory, and can be delivered to the host on demand.

A zero function enables the user to set the unit in either unipolar or bipolar modes as required.

The HC485 sensor and associated electronics are packaged in a rugged, hermetically sealed stainless-steel housing, suitable for use in the most demanding factory floor environments.

The unit's electrical hook-up is accomplished via a six pin MS-style bayonet connector, welded to the lead side of the LVDT, for ease of termination.

Mating connectors can be supplied on request.

HC485 digital LVDTs are available in seven bipolar measurement ranges from 2.5 to 150mm.

Setup software will be supplied with every HC485 unit and a free demo programme is available from the company's website.

Using a standard RS485 to RS232 convertor, the HC485 can be connected to a personal computer and the data pasted directly into a Microsoft Excel spreadsheet.

Future versions of the HC485 will offer improved linearity of 0.05% and increased stroke capability in a sensor of the same overall length, achieved by using linearisation tables within the memory of the built-in processor.

(This was Engineeringtalk's Top Story on 26 March 2002).

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