Inductive encoders get smaller and talk to PLCs

At the recent SPS/IPC/Drives show in Nuremberg, Newall Measurement Systems unveiled several new variants on its inductive linear encoder technology.

In one development (shown above), the British company has moved the electronics from the encoder reader head into a connector, thus producing a compact cylindrical reader that can be mounted easily in machines with restricted spaces. The MCG head offers a choice of outputs including TTL and 1V peak-to-peak signals.

In another development, Newall has produced a family of encoders that will interface directly with most PLCs. The IP67-rated SHG family will withstand dirt, dust, oil and other contaminants that can disrupt the operation of conventional glass-scale linear encoders. They are available with 5-24V or RS-422 TTL outputs.

Newall was also showing a stainless-steel version of its encoder, as well as a couple of prototype variants still looking for applications. One of these combines the linear encoder with a rotary encoder; the other has a reader head that moves like a ballscrew.

Newall`s inductive technology has no bearings, springs or internal moving parts. The company claims that the technology has several advantages over glass-scale systems including: better resistance to shocks and vibration; better protection against the effects of dust, dirt and immersion in water; and the ability to operate over continuous lengths of up to 12m, compared to the 3m limit typical for glass scales

Newall, previously part of the B Elliott group, was bought by California-based BEI Technologies in 2004. BEI has itself been acquired recently by Schneider Electric.