Quadrature Encoder Input Meter for Position or Rate

Accurate Position or Rate from Linear & Rotary Quadrature Encoders

Quadrature meter for linear and rotary encoders

Features

  • Accepts differential or single-ended 5V logic signals from quadrature encoders
  • 6-digit scalable display for position, length or rate
  • Quadrature count x1, x2 or x4
  • Combined encoder pulse rate to 250 kHz
  • Display update rate up to 25/s
  • Zero channel input
  • Universal 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac power
  • Transducer excitation output (isolated)
  • Wide choice of options:
    - 2 or 4 relays, mechanical or solid state (isolated)
    - Analog output (isolated)
    - Serial data I/O: Ethernet, USB, RS485, RS232 (isolated)
Description
Quadrature meter for encoder signals

Position, Length or Angle Measurement

The 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 90° 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.

Scaled Rate Measurement

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.

Quadrature Meter Capabilities

Quadrature Position & Rate Meter
  • 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.

Additional Capabilities

Optional plug-in boards for communications and control include Ethernet and other serial communication boards, dual or quad relay boards, and an isolated analog output board. s may be powered from 85-264 Vac or optionally from 12-32 Vac or 10-48 Vdc. The display is available with red or green LEDs. The 1/8 DIN case meets NEMA 4X (IP65) specifications from the front when panel mounted. Any setup functions and front panel keys can be locked out for simplified usage and security. All power and signal connections are via UL / VDE / CSA rated screw clamp plugs.

Specifications
Display
Readout 6 LED digits, 7-segment, 14.2 mm (.56"), red or green.
Display Range -999999 to +999999, XXXXEX notation beyond 999999
Zero Adjust -999999 to +999999
Span Adjust 0 to 999999
Indicators Four LED lamps
Inputs
Types Differential or single-ended quadrature
Transitions Monitored x1, x2 or x4
Max Pulse Rate 250 kHz at x1, 125 kHz at x2, 62.5 kHz at x4
Position Error No error contributed by meter
Differential High Threshold +200 mV
Differential Low Threshold -200 mV
Differential Limits -11V to +14V
Single-ended High Voltage 2.5V to 10V
Single-ended Low Voltage -1V to +1V
Input Resistance, Typ. 17 kOhm
Quadrature Position Mode
Zero Adjust -999999 to +999999
Span Adjust 0 to 999999
Quadrature Rate Mode
Freq. Technique Inverse period
Conversion Time Gate time + 30 ms+ 0-2 signal periods
Gate Time Selectable 10 ms to 199.99 s
Time Before Zero Out Selectable 10 ms to 199.99 s
Output & Display Update Same as conversion time
Time Base Accuracy Calibrated to ±2 ppm
Power
Voltage, standard 85-264 Vac or 90-300 Vdc
Voltage, optional 12-32 Vac or 10-48 Vdc
Frequency DC or 47-63 Hz
Power Consumption (typical, base meter) 1.2W @ 120 Vac, 1.5W @ 240 Vac, 1.3W @ 10 Vdc, 1.4W @ 20 Vdc, 1.55W @ 30 Vdc, 1.8W @ 40 Vdc, 2.15W @ 48 Vdc
Power Isolation 250V rms working, 2.3 kV rms per 1 min test
Excitation Output (standard)
5 Vdc 5 Vdc ± 5%, 100 mA
10 Vdc 10 Vdc ± 5%, 120 mA
24 Vdc 24 Vdc ± 5%, 50 mA
Output Isolation 50 Vdc to meter ground
Analog Output (optional)
Output levels 4-20 mA, 0-20 mA, 0-10V, -10 to +10V (single-output option)
Current compliance 2 mA at 10V ( > 5 kΩ load)
Voltage compliance 12V at 20 mA (< 600Ω load)
Scaling Zero and full scale adjustable from -99999 to +99999
Resolution 16 bits (0.0015% of full scale)
Isolation 250V rms working, 2.3 kV rms per 1 min test
(dual analog outputs share the same ground)
(optional)
Relay types 2 Form C contact relays or 4 Form A contact relays (NO) 2 or 4 Form A, AC/DC solid state relays (NO)
Current Ratings 8A at 250 Vac or 24 Vdc for contact relays 120 mA at 140 Vac or 180 Vdc for solid state relays
Output common Isolated commons for dual relays or each pair of quad relays
Isolation 250V rms working, 2.3 kV rms per 1 min tes
Serial Data I/O (optional)
Board selections RS232, RS485 (dual RJ11 or RJ45 connectors), USB, Ethernet, USB-to-RS485 converter, Ethernet-to-RS485 converter
Protocols Modbus RTU, Modbus ASCII, Modbus TCP (Ethernet), TDM ASCII
Data rates 300 to 19200 baud
Digital addresses 247 (Modbus), 31 (TDM ASCII),
Isolation 250V rms working, 2.3 kV rms per 1 min test
Environmental
Operating temperature 0°C to 55°C
Storage temperature. -40°C to 85°C
Relative humidity 95% at 40°C, non-condensing
Protection NEMA-4X (IP-65) when panel mounted
Applications
Using Quadrature for Cutting to Length
Using a  quadrature panel meter to cut material to length Controlling the repetitive cutting of material to length is an excellent application of the quadrature meter. The quadrature encoder shares the shaft of a sensing wheel, whose rotation corresponds to lineal displacement of material. The meter compares the displacement reading against setpoint information, and then uses its dual relays to first slow down and then cut the material.
Using Quadrature for X-Y Positioning
Using a  quadrature panel meter for X-Y positioning Accurate X-Y position or rate can be obtained from two shaft encoders, which convert linear position to quadrature signals as a shaft turns. In addition to serving as a display, each can use its optional dual relay setpoint capability for closed loop control. It can also transmit data via RS232, RS485, or a 4-20 mA analog signal.
Using Quadrature to Monitor a Drilling Operation
Using a  quadrature meter to monitor an oil drilling operation Quadrature can be used to track position and vertical drilling speed of the bit in an oil drilling operation. A shaft encoder is rotated by a cable that moves with the drilling shaft. In this application, the same encoder signal is applied to a quadrature meter for position, and to a second quadrature meter for rate. Both meters can be scaled to read out in appropriate engineering units, such as feet and inches per minute, and can be alarmed. A 6-digit remote display could be added to read out peak rate.

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