Chapter 3
Signal Connections
PC-DIO-24/PnP User Manual
3-4
©
National Instruments Corporation
Caution:
During programming, note that each time you configure any port, output
ports A and C are reset to 0, and output port B is undefined.
Digital I/O Signal Connections
The following specifications and ratings apply to the digital I/O lines.
The maximum input logic high and output logic high voltages assume a
Vcc supply voltage of 5.0 V.
The absolute maximum voltage rating is –0.5 to +5.5 V with respect to
GND.
Digital input specifications (referenced to GND):
Input logic high voltage
2.2 V min
5.3 V max
Input logic low voltage
–0.3 V min
0.8 V max
Input high current
(Vin = 5 V, W1 set to pullup)
—
11.0
µ
A max
Input high current
(Vin = 5 V, W1 set to pulldown)
—
65
µ
A max
Input logic low current
(Vin = 0 V, W1 set to pullup)
—
–65
µ
A max
Input logic low current
(Vin = 0 V, W1 set to pulldown)
—
–11
µ
A max
Table 3-2.
Port C Signal Assignments
Programming
Mode
Group A
Group B
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
Mode 0
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
Mode 1 Input
I/O
I/O
IBF
A
STB
A
*
INTR
A
STB
B
*
IBFB
B
INTR
B
Mode 1 Output
OBF
A
*
ACK
A
*
I/O
I/O
INTR
A
ACK
B
*
OBF
B
*
INTR
B
Mode 2
OBF
A
*
ACK
A
*
IBF
A
STB
A
*
INTR
A
I/O
I/O
I/O
* Indicates that the signal is active low.
!
