Micro quadrature meters with the Standard counter main board accept the A & B signals from 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 produced. The meter totalizes the counts and then scales the total in soft-ware for display and control. A zero index 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
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 as by the meter as corresponding to an integral number of revolutions of the shaft encoder. It is used by the meter 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 current total may be stored in non-volatile memory and can be used as the starting point for counting when power resumes. Power fail or zero index capabilities are alternate meter setup choices.
A built-in isolated 5, 10, or 24 Vdc excitation supply can power the encoder and eliminate the need for an external power supply. Plug-in isolated analog output, dual-setpoint controller, and RS232/485 serial communications boards can upgrade Micro and Mighty Series quadrature meters from stand-alone monitor to system interface and control. In particular, the meter can provide an isolated 4-20 mA output signal scaled to the display.
Micro Series meters can be powered from 95-240 Vac ±10% and 95-370 Vdc, or optionally from 12-34 Vac and 10-48 Vdc. Any setup functions and front panel keys may be locked out for simplified usage and security. The popular 1/8 DIN version with 0.56″ high digits is environmentally sealed to NEMA-4X (IP65) from the front when panel mounted, and is available with red or green LEDs.
6 digits, 7-segment
Available with 0.56", 1.0", 4.0" or 5.0" digits.
High brightness red. Green available with 0.56" digits.
-999999 to +999999
Display Update Rate
Programmed gate time + 30 ms + 1-2 signal periods
Four LED lamps
Differential or single-ended quadrature
x1, ×2 or ×4
Max Pulse Rate
250 kHz at ×1, 125 kHz at ×2, 62.5 kHz at ×4
No error contributed by meter
+ 30 ms + 0-2 signal periods
Selectable 10 ms to 199.99 s
Selectable 10 ms to 199.99 s
Output & Display Update
Same as conversion time
Time Base Accuracy
Calibrated to ±2 ppm
±1 ppm/°C (typ.)
95-240 Vac ±10% and 95-370 Vdc
12-34 Vac and 10-48 Vdc
DC or 49-440 Hz
Safety-rated to 250 Vac, meter ground to earth ground,
DC to 60 Hz, 4.2 kVp per High Voltage Test
5 Vdc ±5%, 100 mA max
10 Vdc ±5%, 120 mA max
24 Vdc ±5%, 50 mA max
50 Vdc to meter ground
0°C to 60°C
-40°C to 85°C
95% at 40°C, non-condensing
NEMA-4X (IP-65) when panel mounted
Using Quadrature for Cutting to Length
Controlling the repetitive cutting of material to length is an excellent application of the Micro 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
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 Micro quadrature meter 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
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 Micro 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 Micro 6-digit remote display could be added to read out peak rate.