National Instruments NI 781xR - Manual (Page 21)

Chapter 2 Hardware Overview of the NI 781xR
© National Instruments Corporation 2-3 NI 781xR User Manual
Caution Exceeding the maximum input voltage ratings listed in Table B-2, NI 781xR I/O
Signal Summary , can damage the NI 781xR and the computer. NI is not liable for any
damage resulting from such signal connections.
Caution Do not short the DIO lines of the NI 781xR directly to power or to ground. Doing
so can damage the NI 781xR by causing excessive current to flow through the DIO lines.
You can connect multiple NI 781xR digital output lines in parallel to
provide higher current sourcing or sinking capability. If you connect
multiple digital output lines in parallel, your application must drive all of
these lines simultaneously to the same value. If you connect digital lines
together and drive them to different values, excessive current can flow
through the DIO lines and damage the NI 781xR. Refer to Appendix A,
Specifications , for more information about DIO specifications. Figure 2-2
shows signal connections for three typical DIO applications.
Figure 2-2. Example Digital I/O Connections
*3.3 V CMOS
†
Use a pull-up resistor when driving 5 V CMOS devices
LED
TTL, LVTTL, CMOS, or LVCMOS Signal
+5 V
Switch
I/O Connector
DGND
NI 781xR
DIO<0..3>
DIO<4..7>
+5 V
5 V CMOS
†
TTL or
LVCMOS*
Compatible
Devices
DGND