Power Terminals; Ground Terminals - Measurement Computing USB-1616FS User Manual

USB-1616FS User's Guide Functional Details
When you configure the digital bits for input, you can use the USB-1616FS digital I/O terminals to detect
the state of any TTL-level input. Refer to the switch circuit shown in Figure 3-5 and the schematic shown
in Figure 3-6. If you set the switch to the +5V position, DIO4 reads TRUE (1). If you move the switch to
the GND position, DIO4 reads FALSE (0).
Figure 3-5. Digital connection DIO4 detecting the state of a switch
DIO4
GND 5V
Figure 3-6. Schematic showing switch connection to digital channel DIO4
For more information on digital signal connections
For general information regarding 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).

Power terminals

The terminal (labeled ) draws power from either the USB connector VBUS terminal or the external
+5V 5V
power supply.
Caution! The +5V terminal is an output. Do not connect to an external power supply or you may
damage the USB-1616FS and possibly the computer.
The maximum amount of +5 V current from the +5 V terminal is limited to 50 mA.

Ground terminals

The USB-1616FS has 16 analog ground connections ( ) and eight digital ground connections
AGND 0 to 15
( ). The analog ground connections provide a common ground for the analog input channels. The
GND 0 to 7
ground connections provide a common ground for the to , , , and
DIO 0 DIO 7 TRIG IN CTR SYNC VDC
connections.
3-6