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 portB is undefined.
Digital I/O Signal Connections
The following specifications and ratings apply to the digitalI/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 µA max
Input high current
(Vin = 5 V, W1 set to pulldown) — 65 µA max
Input logic low current
(Vin = 0 V, W1 set to pullup) — –65 µA max
Input logic low current
(Vin = 0 V, W1 set to pulldown) — –11 µA 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 IBFASTBA*INTRASTBB*IBFBBINTRB
Mode 1 Output OBFA*ACKA*I/O I/O INTRAACKB*OBFB*INTRB
Mode 2 OBFA*ACKA*IBFASTBA*INTRAI/O I/O I/O
* Indicates that the signal is active low.
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