MCC USB-1808X: High-Speed, High-Precision, Simultaneous USB DAQ Device - Datasheet

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USB-1808 Series
Counter Input
USB-1808 Series devices have two 32-bit general-purpose counter
inputs that can be read asynchronously under program control,
or synchronously as part of a digital scan group.
Each counter can accept frequency inputs up to 50 MHz and
supports the following software-selectable counter input modes:
• Totalize – High-speed pulse counter for general counting
applications. The internal counter increments when the
TTL levels transition from low to high or from high to low.
• Period measurement – Measure the period of a signal at a
counter channel input. Users can measure x1, x10, x100 or
x1000 periods for 32-bit values. Four resolutions are avail-
able — 20 ns, 200 ns, 2000 ns, or 20,000 ns
• Pulse-width measurement – Measure the time from the
rising edge to the falling edge, or vice versa, on a signal on
a counter input. Four resolutions are available — 20 ns,
200 ns, 2000 ns, or 20,000 ns.
Each mode supports additional counter options. When counter
options are set, the counters can concurrently monitor time
periods, frequencies, pulses, and other event-driven incremen-
tal occurrences directly from pulse-generators, limit switches,
proximity switches, and magnetic pick-ups.
Quadrature Encoder Input
USB-1808 Series devices can simultaneously decode signals
from up to two quadrature encoders. Encoders with a 50 MHz
maximum pulse frequency and X1, X2, and X4 count modes
are supported.
Each device provides A, B, and Z inputs for each connected
encoder. A typical encoder generates the A and B signals at a 90°
phase shift with respect to each other. These signals are used to
determine system position (counts), velocity (counts per second),
and direction of travel or rotation.
Timer Output
Two timers can generate pulse rates of up to 50 MHz each, with
programmable pulse widths down to 10 ns. The timer output
rate and pulse width can be updated asynchronously at any time,
however doing so results in a pulse stream that is not seamless.
Timer output operations can be paced by the internal clock or
by an external clock, and can be initiated by a digital trigger.
Synchronous I/O – Mixing Analog,
Digital, and Counter Scanning
USB-1808 Series devices can read analog, digital, counter , and
encoder inputs, and generate up to two analog outputs and one
digital pattern output at the same time. Digital, counter, and
encoder inputs do not affect the overall A/D rate because these
inputs use no time slot in the scanning sequencer.
For example, one analog input channel can be scanned at the
maximum A/D rate along with digital, counter, and encoder
input channels.
Each analog channel can have a different gain, and digital,
counter, and encoder channels do not need additional scan-
ning bandwidth as long as there is at least one analog channel
in the scan group.
Digital input channel sampling is done during the dead time of
the scan period when no analog sampling is being done.
Clock I/O
USB-1808 Series devices provides two external clock inputs –
one for pacing input scan and the other to pace output scans.
These devices also include two clock outputs – one to output the
internal or external clock used for input scans, and the other
to output the internal or external clock used for output scans.
Triggering
USB-1808 Series devices support digital triggering and pattern
triggering.
The ITRIG and OTRIG pins are used for external TTL-level trig-
gering – ITRIG can trigger input scans, and OTRIG can trigger
output scans. The trigger mode is software-selectable for edge or
level sensitive, rising or falling edge, high or low level.
USB-1808 Series devices can also start an input or output scan
with a digital pattern trigger using any of the four DIO ports. A
scan is triggered when a specified pattern is detected. Specific
bits can be masked or ignored. A digital pattern can be input or
output under the timing control of a clock signal.
Calibration
The USB-1808 Series devices are factory-calibrated using a NIST-
traceable calibration process. Specifications are guaranteed for
one year. For calibration beyond one year, return the device to
the factory for recalibration.
USB-1808 Series OEM Versions
OEM versions have board-only form factors with header con-
nectors for OEM and embedded applications (no case, CD, or
USB cable included). All devices can be further customized to
meet customer needs.
The OEM versions have the same specifications as the standard
devices, but come in a board-only form factor with header connectors
instead of screw terminals.
Features