Measurement Computing

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USB-1602HS and USB-1604HS Series

Counter Input

USB-1602HS and USB-1604HS Series devices have four counters

that accept frequency inputs up to 20 MHz. The counter chan-

nels can be read as 16-bit or 32-bit counters. The default input

type is TTL, rising-edge triggered.

Counters can be used to concurrently monitor time periods, fre-

quencies, pulses, and other event-driven incremental operations.

Users can map counter channels to gate a counter, decrement a

counter, or latch the current count to the count register. Users

can also configure a counter to be gated by another counter

input that is mapped as a gate input.

Counters can be read asynchronously under program control,

or synchronously as part of an analog or digital scan group.

• When read synchronously, all counters are set to zero at

the start of an acquisition.

• When read asynchronously, counters may be cleared on

each read, count up continually, or count until the 16-bit

or 32-bit limit is reached.

Counter, period, pulse width measurement (PWM), and timing

counter modes are supported.

Quadrature Encoders

Users can connect up to three quadrature encoders to measure

linear and rotary position. Encoders with a 16-bit (counter low)

or a 32-bit (counter low and counter high) counter, 6 MHz

maximum pulse frequency, and X1, X2, and X4 count modes

are supported. Each input can be debounced to eliminate noise

or false edges, or to switch induced transients.

Trigger Input

The USB-1602HS and USB-1604HS Series supports hardware and

software triggering.

With hardware-based triggers, an output value is compared

in hardware to an input level on a specified channel. These

hardware-based triggers are supported:

• Analog input hardware

• External digital trigger input (DIG TRIG pin)

With software-based triggers, an analog, digital, or counter

reading is checked by the computer in order to detect a trigger

event. These software-based triggers are supported:

• Analog software trigger

• Digital pattern

• Counter/totalizer

These software triggers can also be used to stop an acquisition.

Features

Timer Output

The USB-1602HS and USB-1604HS Series have two timer outputs

for generating pulse width waves. The duty cycle and frequency

are software-selectable. Timer outputs can be updated asynchro-

nously at any time.

Clock I/O

The USB-1602HS and USB-1604HS Series have independent

input and output pacing clocks.

Users can pace analog, digital, and counter input scans with the

internal input clock or an external clock. Analog channels can

be paced from 0.75 µs to 1000 seconds in 20.83 ns steps. Digital

and counter inputs can be paced from 250 ns to 1 second in

20.83 ns steps. The clock rate is 8 MHz maximum for both the

internal input clock and external input clock.

Users can pace analog, digital, and timer output operations

with the internal input clock, internal output clock, external

input clock, or external output clock. The clock rate is 1 MHz

maximum for analog output operations, and 8 MHz maximum

for digital operations with no analog channels enabled.

Setpoint Detection

Users can configure a detection setpoint for each analog input

channel. Setpoint detection can be used to update an output

channel with an input channel value, or to write a specified

value to a digital output port, when specified criteria is met. This

allows for real-time control based on acquisition data. Setpoint

detection criteria is configurable with software.

Signal Connections

A 68-pin SCSI connector provides connections for all signal I/O

except analog inputs.

BNC connectors provide connections for the analog inputs,

and alternate connections for the external clock and external

digital trigger input.

Calibration

USB-1602HS and USB-1604HS Series devices are factory-calibrat-

ed using a NIST-traceable calibration process. Correction factors

for each range are stored on the device at the time of calibration.

Specifications are guaranteed for one year. For calibration beyond

one year, return the device to the factory for recalibration.

USB-1602HS and USB-1604HS Series devices support field calibra-

tion. Field calibration traceability is derived through the onboard

reference. Use the InstaCal utility to calibrate the device after

it has fully warmed up and immediately before making critical

measurements.