Design Engineering

POSITAL extends interface options for OPTOCODE rotary encoders


General DPN

POSITAL’s OPTOCODE (OCD) absolute rotary encoders are now available with a new combined interface that enables simultaneous communication of both absolute and incremental rotary position data.

The new interface is designed to provide robust and cost-effective point-to-point communications between encoders and many popular types of programmable logic controllers (PLC).

The new interface reports absolute rotary position data to the PLC using the synchronous serial interface (SSI) standard, operating over an RS-422/485 communication link. At the same time, the encoder can also transmit a series of electronic pulses as the shaft rotates – up to 16,384 pulses per rotation. Optionally, an index pulse can also be sent once every complete rotation. Incremental pulses can be sent over an RS-422/485 link, or via a push/pull connection.

(The incremental pulses are sent over separate wire pairs from those used to enable the SSI interface.) These “dual-personality” encoders can be extremely useful for motor control applications or for monitoring rotating machinery such as wind turbines, since they can provide accurate real-time measurement of the rotational velocity (thanks to the incremental output), while also providing access to absolute rotary position data in response to a request from  the controller.  


Other new features of these encoders include enhanced diagnostic reporting via case-mounted LED’s or via the SSI connection, and an optional case-mounted push-button that allows the operator to re-set the zero-position (datum) of the absolute position readout. The new OCD encoders retain the best features of the previous generation devices, including precision (up to 216 steps per turn) accuracy, single- or multi-turn capabilities and highly effective shaft and connection seals (up to IP66 protection). Available as solid, hollow and hub shaft versions, the units can be supplied with a connector or a cable exit.


Stories continue below

Print this page

Related Stories