Measurement Computing USB-1602HS-2AO - Manual (Page 18)

USB-1602HS-2AO User's Guide Functional Details
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The clock rate is 8 MHz maximum for both the internal pacer clock and external input scan clock.
Output clock pacing
Analog, digital, and timer operations can be paced using the internal output pacer clock (independent of the
internal pacer clock), an external output pacer clock connected to the XDPCR pin on the SCSI connector, the
internal programmable input pacer, or an external input pacing clock connected to either the XAPCR pin on the
SCSI connector or the
EXT CLK BNC connector.
The clock rate is 1 MHz maximum for analog output operations, and 8 MHz maximum for digital operations in
which no analog channels are enabled.
Analog inputs
The USB-1602HS-2AO has two single-ended analog inputs. Each input has a dedicated 16 bit A/D converter
that provides true simultaneous sampling at rates of up to 2 MHz per channel. The input range is software
selectable for ±10 V, ±2.5 V, or ±500 mV.
You can pace analog input operations with the internal A/D pacer clock or with an external clock source. When
using an external input scan clock, connect the clock source to the
XAPCR pin on the SCSI connector or the
EXT CLK BNC connector.
Analog outputs
The USB-1602HS-2AO has two independent, 16-bit, analog output channels. The analog output range is -10V
to +10V.
Each DAC channel can continuously output a waveform at up to 1 MHz. You can clock the DAC channels with
the internal DAC scan clock or with an external DAC input clock. The internal analog input pacer clock can
pace both the DAC output and the analog input simultaneously.
When using an external output scan clock, connect the clock source to the XDPCR pin on the SCSI connector or
the EXT CLK BNC connector.
Digital I/O
The USB-1602HS-2AO has 32 CMOS digital I/O lines configured as 16 digital inputs and 16 digital outputs.
You can pace digital operations with the onboard scan clock or an external source. The maximum DIO transfer
rate is 8 MS/s (software paced).
Digital input scanning
Digital input ports can be read synchronously along with analog channels in a scan, or asynchronously before,
during, or after an analog input scan.
The digital inputs can sustain rates of up to 8 MS/s for one channel when no analog channels are sampled, and
rates of up to 2 MS/s when analog channels are also sampled.
Internal pull-up/pull-down capability (J14)
Unconnected inputs are pulled high to +3.3V through 100 k resistors via a 4-pin jumper on the PCB board
(
J14 ). To configure these inputs to pull low (0 V), do the following:
1. Remove the 4 screws from the rear panel.