Measurement Computing USB-1608GX-2AO-OEM - Manual (Page 15)

USB-1608GX-2AO-OEM User's Guide Functional Details
15
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.
Retrigger mode
Retrigger mode lets you set up repetitive analog input or output trigger events. The trigger is automatically re-
armed after it is activated. Use software to set the A/D or D/A trigger count (the number of samples you want
per trigger).
Counter input
The CTR0 and CTR1 terminals are 32-bit event counters that can accept frequency inputs up to 20 MHz. The
internal counter increments when the TTL levels transition from low to high.
Timer output
The TMR terminal is a pulse width modulation (PWM) timer output that can generate a pulse output with a
programmable frequency in the range of 0.0149 Hz to 32 MHz. The timer output parameters are software
selectable. Figure 8 shows the timer output schematic.
Figure 8. Timer output schematic
Power output
The +5V terminal can output up to 10 mA maximum. You can use this terminal to supply power to external
devices or circuitry.
Caution! The
+5V terminal is an output. Do not connect to an external power supply or you may damage the
device and possibly the computer.
Ground
The analog ground ( AGND ) terminals provide a common ground for all analog channels.
The digital ground ( GND ) terminals provide a common ground for the digital, counter, timer, and clock
channels and the power terminal.