Digital I/O Terminals (Dio0 To Dio7) - Measurement Computing USB-1608FS User Manual

USB-1608FS User's Guide
The following image shows the single-ended measurement data acquired by TracerDAQ.
For more information on analog signal connections
For more information on single-ended inputs, refer to the Guide to Signal Connections (this document is
available on our web site at www.mccdaq.com/signals/signals.pdf).

Digital I/O terminals (DIO0 to DIO7)

You can connect up to eight digital I/O lines to the screw terminal containing pins 21 to 40 (
Refer to the pinout diagram on page 3-3 for the location of these pins. You can configure each digital bit for
either input or output. All digital I/O lines are pulled up to USB +5 V with a 47 K resistor (default). You can
request the factory to configure the resistor for pull-down to ground if desired.
When you configure the digital bits for input, you can use the USB-1608FS digital I/O terminals to detect the
state of any TTL-level input. Refer to the switch circuit shown in
3-6 . If you set the switch to the +5 V input, DIO0 reads TRUE (1). If you move the switch to GND, DIO0 reads
FALSE (0).
Figure 3-4. TracerDAQ showing single-ended measurement data
Pin 40
GND
Figure 3-5. Digital connection DIO0 detecting the state of a switch
Figure 3-5 and the schematic shown in
Pin 21
DIO0
Pin 39
PC +5V
3-5
Functional Details
to ).
DIO0 DIO7
Figure