Chapter 3 Connector Information

Table 3-1.I/O Connector Signals (Continued)

Signal Name

Reference

Direction

Description

 

 

 

 

 

 

 

 

AO GND

—

—

Analog Output Ground—AO GND is the reference for

 

 

 

AO <0..1>. All three ground references—AI GND,

 

 

 

AO GND, and D GND—are connected on the device.

 

 

 

 

D GND

—

—

Digital Ground—D GND supplies the reference for

 

 

 

PFI <0..15>/P0/P1 and +5 V. All three ground

 

 

 

references—AI GND, AO GND, and D GND—are

 

 

 

connected on the device.

 

 

 

 

+5 V

D GND

Input or

+5 V Power—These terminals provide a +5 V power

 

 

Output

source or can be used to externally power the PFI outputs.

 

 

 

 

PFI <0..3>,

D GND

Input

Programmable Function Interface or Static Digital

PFI <8..11>/P0.<0..7>

 

 

Input Channels 0 to 7—Each PFI terminal can be used

 

 

 

to supply an external source for AI, AO, or counter/timer

 

 

 

inputs.

 

 

 

You also can use these terminals as static digital input

 

 

 

lines.

 

 

 

 

PFI <4..7>,

D GND

Output

Programmable Function Interface or Static Digital

PFI <12..15>/P1.<0..7>

 

 

Output Channels 0 to 7—You can route many different

 

 

 

internal AI, AO, or counter/timer outputs to each PFI

 

 

 

terminal.

 

 

 

You also can use these terminals as static digital output

 

 

 

lines.

 

 

 

 

NC

—

—

No connect—Do not connect signals to these terminals.

 

 

 

 

+5 V Power

The +5 V terminals on the I/O connector can be use as either an output or an input. Both terminals are internally connected on the USB-621x.

+5 V Power as an Output

Because the USB-621xdevices are bus powered, there is a 50 mA limit on the total current that can be drawn from the +5 V terminals and the digital outputs PFI <4..7> and PFI <12..15>/P1.<0..7>. The USB-621xmonitors the total current and will drop the voltage on all of the digital outputs and the +5 V terminals if the 50 mA limit is exceeded.