
Chapter 3 Signal Connections
© National Instruments Corporation 3-17 PCI-1200 User Manual
Logical Inputs and Outputs•Absolute max voltage rating –0.5 to +5.5V with respect to DGND
•Digital I/O lines:
–Input logic low voltage –0.3V min 0.8 V max
–Input logic high voltage 2.2V min 5.3V max
–Output logic low voltage —0.4V max
(at output current = 2.5 mA)
–Output logic high voltage 3.7V min —
(at output current = –2.5 mA)
–Input leakage current –1 µA min 1 µA max
(0 < Vin < 5V)
Figure 3-8 illustrates signal connections for three typical digital I/O
applications.
Figure 3-8. Digital I/O Connections
In Figure3-8, port A is configured for digital output, and ports B and C are
configured for digital input. Digital input applications include receiving
TTL signals and sensing external device states such as the switch in
TTL Signal
13
DGND
I/O Connector PCI-1200
30 PC0
22 PB0
+5 V
+5 V
LED
14 PA0 Port A
PA<7..0>
Port B
PB<7..0>
Port C
PC<7..0>