Single-axis DRO

The Micro Position Sensor 3 (MPS3)

The latest incarnation of the ever popular Micro Position Sensor from BW Electronics is a battery-powered, fully featured single-axis readout in a compact and robust aluminium box.

MPS3 single-axis readout
The Micro Position Sensor 3, a battery-powered single-axis DRO designed and manufactured by BW Electronics.

Features of the MPS3

The MPS3 meets the needs of the job

  • The battery will last for about 1 year with normal use, and 3 years in “minimum power, always on” mode.
  • The MPS3 has an extended measuring range of 500mm or 20″ maximum.
  • The red LED display with five digits plus “–” sign is easy to read, even in dim light.
  • Any position between ±999.99 mm or ±99.9995 inches can be displayed.
  • Measurements can be shown in millimetres or inches, and the MPS3 can convert between them.
  • The position display can be zeroed at any time.
  • Nine datum points are available.
  • The MPS3 can recover all nine datum positions after being switched off or after an overspeed error.

The MPS3 fits almost anywhere

  • The readout is very small, just 93 x 38 x 32 mm.
  • It is robust, enclosed in a die-cast aluminium box.
  • It can be mounted using a simple stainless steel clip.
  • A single MPS3 can be moved between two or more locations quickly and easily.
  • It can operate in a wide range of environmental conditions: temperature 0 to 35 °C, humidity 20–80% non-condensing.

The MPS3 helps you in your work

  • You can pre-enter positions into the display.
  • The position display can be halved at the touch of a key, which is useful on milling machines for centre-finding the work.
  • The position display can be doubled at the touch of a key, which is useful on a lathe cross-slide to measure the diameter rather than the radius.
  • On detecting movement, the readout delays turning off the display during power management.
  • The position display can be zeroed at any time.
  • The display automatically wakes up on movement or key press.

The MPS3 can be adapted to your use

  • The readout is designed to be moved between different positions or machines using a simple clip attachment and a pin or hook for the measuring wire.
  • The MPS3 has a unique wire exit guide shaped like a funnel with curved sides. This allows measurement over a full ±90°.
  • The sensitivity can be recalibrated to nearly any possible value, so that 10 mm of movement can be displayed as 5 mm or 20 mm etc.
  • The sophisticated power management system means the MPS3 can be fitted into almost any measurement process while maximising battery life.
  • The MPS3 can operate with the display always on, and can be turned off at the press of a key.
  • Its use as a long-term movement sensor is limited only by battery life.

How the MPS3 sensor works

The defining feature of the MPS3 is that the sensor is ‘intelligent’; that is, it has its own controlling microprocessor.

The MPS3 works on the principle of wrapping a flexible stranded stainless steel wire around a spring-loaded drum; the drum is then mounted on the shaft of a rotary optical encoder. As the wire is pulled our or returned under the spring tension, the rotary encoder is turned and produces direction and distance pulses. To provide the best possible accuracy, the return spring has a constant torque and the drum on which the wire winds is threaded to prevent overlapping turns.

Attached to the encoder is a microprocessor that couts the encoder pulses and, by use of an internal calibration constant, converts the pulses into a dimension in either inches or millimetres. This calibration constant is not a fixed quantity: it can be changed at any time.

The MPS3 uses a rotary optical encoder that is optimised for position sensing, and so the sensor is physically small. It can be easily mounted and moved between machines. It is supplied ready-to-fit; there is no need to calibrate it beforehand.

Digital Position Readouts for smaller machine tools