Laurel Quadrature Encoder Position & Rate Meter

The Laurel quadrature meter with the Standard counter main board accepts the A & B quadrature signals from linear encoders and shaft encoders to provide a highly accurate, scaled display of position, length, or angle in engineering units, such as ft, cm or degrees. The A & B quadrature signals are 90º out of phase, and their phase relationship determines whether up counts (+) or down counts (-) are counted. The meter totalizes the counts and then scales the total in software for display and control. A zero index signal, or Z signal, may be added as a third input to the A & B signals.

Use of the Extended counter main board can convert the quadrature meter from scaled position to scaled rate. For example, it can display the speed of a moving slab in ft/sec. Simultaneous display of position and rate will require two meters. The display and control output update rate for position or rate is normally set to a maximum of 25/s, as determined by a user-programmable gate time.

One, two or four transitions may be counted at a maximum combined rate of 250 kHz and be mathematically scaled for display in engineering units from -999,999 to +999,999. The quadrature board has input circuitry which may be jumpered for either single-ended input signals or for balanced line driver signals. Anti-jitter circuitry eliminates errors produced by vibration of the encoder.

A zero index pulse, if available, is interpreted by the meter as indicating a zero reference for an integral number of revolutions of a rotary shaft encoder or the home position of a linear encoder. It is used by the meter for initializing and to correct for any cumulative pulse count errors. Special circuitry corrects for width of the zero index pulse.

 

In the event of a power failure, the latest total may be stored in non-volatile memory and can be used as the starting point for counting when power resumes. Power fail save or zero index capabilities are alternate meter setup choices.