Digital I/O; Trigger Input - Measurement Computing USB-1608G-OEM User Manual

USB-1608G-OEM User's Guide

Digital I/O

You can connect up to eight digital I/O lines to
configurable for input or output. The digital I/O terminals can detect the state of any TTL-level input. Refer to
the schematic shown in Figure 5.
Figure 5. Schematic showing switch detection by digital channel DIO0
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).
Pull-up/down configuration
Unconnected inputs are pulled low by default to 0 V through 47 kΩ resistors via jumper
(see Figure 6).
The pull-up/pull-down voltage is common to all 47 kΩ resistors. Jumper W1 is configured by default for pull-
down. Figure 7 shows the jumper configured for pull-up and pull-down.
Caution! The discharge of static electricity can damage some electronic components. Before touching the
board, ground yourself using a wrist strap or touch the computer chassis or other grounded object
to eliminate any stored static charge.
For more information about digital signal connections
For general information about digital signal connections and digital I/O techniques, refer to the Guide to Signal
Connections (available on our web site at www.mccdaq.com/signals/signals.pdf).

Trigger input

The TRIG terminal is an external digital trigger input. The trigger mode is software selectable for edge or level
sensitive.

Edge sensitive mode is configurable for rising or falling edge.

Level sensitive mode is configurable for high or low level.
The default setting at power up is edge sensitive, rising edge.
through
DIO0 DIO7
Figure 6. W1 jumper location
Figure 7. W1 jumper configurations
14
. Each digital channel is individually
W1
Functional Details
on the circuit board