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This Counter Meter accepts the "A" and "B" signals from a conventional shaft encoder to provide a highly accurate, scaled display of position, length, or angle in desired engineering units (such as ft., cm, or degrees).  For examples of typical Model 2135 operations, see the following applications:

	Using Quadrature for Cutting to Length
	Using Quadrature for X-Y Positioning
	Using Quadrature to Monitor a Drilling Operation

The A and B quadrature signals are 90° out of phase, and their phase relationship determines whether up counts (+) or down counts (–) are generated.  The 2135 totalizes the counts and then scales the total in software for display and control.  A zero index signal may be added as a third input to the A and B signals (see below).

One, two, or four transitions may be counted at a maximum combined rate of 250 kHz, and may be mathematically scaled for display in engineering units from -999,999 to +999,999.

The 2135's input circuitry may be jumpered for either single-ended input signals or for balanced line-driver signals.  Antijitter circuitry eliminates errors produced by vibration of the encoder.

A ZERO INDEX pulse, if available, is interpreted by the meter as corresponding to an integral number of revolutions of the shaft encoder.  It is used to correct for any cumulative pulse-count errors.  Special circuitry corrects for width of the zero index pulse.

In the event of power failure, the current total may be stored in nonvolatile memory, to be used as the starting point for counting when power resumes.  Note that power failure and zero index capabilities are alternative meter setup choices.

The meter's built-in isolated 5, 10, or 24 V-DC excitation supply can power the encoder, thus eliminating the need for an external supply.

The following 2000 Series options can be used to upgrade the 235 from a stand-along monitor to a system controller (in particular, the meter can provide an isolated 4-20 mA output signal scaled to the display):

	Isolated Relay Outputs
	Isolated Analog Output
	RS232 or RS485 Interface
	BCD Digital Interface
	Low AC/DC Power

In addition, the "EXTENDED COUNTER" option converts the 2135 from a scaled position meter to a scaled rate meter.  As such, it can be used, for example, to display the speed of a moving slab in ft/sec.  The display and control output update rate for position or rate is normally set to a maximum of 25/s, as determined by the user-programmable gate time (see General Counter Meter Specifications).  Note that the simultaneous display of position and rate will require two separate meters.  For more information on this option, contact the factory.

Quadrature Encoder Meter Specifications  [Top ] (Click here for 2000 Series General Specifications)
Input Type	Low-Level differential or single-ended 5-V logic-level outputs from shaft encoders
Transitions Monitored	x1, x2, or x4
Maximum Pulse Rate	250 kHz at x1; 125 kHz at x2; 62.5 kHz at x4
Position Error	No error contributed by meter
Rate Operation	See General Counter Meter Specifications
Time Base Accuracy	Crystal calibrated to ± 2 ppm
Span Temperature Coefficient	± 1 ppm/°C (typical)
Long-Term Drift	± 5 ppm/year