Chapter 2 Configuration and Installation
© National Instruments Corporation 2-27 SCXI-1120 User Manual
The digital output signal is pin 26:
• Pin 26 is SERDATOUT and is equivalent to SCXIbus MISO when jumper W43 is in
position 1.
The digital I/O signals of the SCXI-1120 match the digital I/O lines of the MIO-16 board. When
used with an SCXI-1341, SCXI-1342, or SCXI-1344 cable assembly, the SCXI-1120 signals
match the digital lines of the Lab-NB/Lab-PC+/Lab-LC boards and the PC-LPM-16 board,
respectively. Table 2-9 lists the equivalences. For more information, consult Appendix E,
SCXI-1120 Cabling.
Table 2-9. SCXIbus to SCXI-1120 Rear Signal Connector to
Data Acquisition Board Pin Equivalences
SCXIbus Line SCXI-1120
Rear Signal
Connector
MIO-16 Board Lab-NB/Lab-PC/
Lab-PC+/Lab-LC PC-LPM-16
MOSI SERDATIN ADIO0 PB4 DOUT4
D*/A DAQD*/A ADIO1 PB5 DOUT5
INTR* SLOT0SEL* ADIO2 PB6 DOUT6
SPICLK SERCLK EXTSTROBE* PB7 DOUT7
MISO SERDATOUT BDIO0 PC1 DIN6
The digital timing signals are pins 36 and 43:
• Pin 36 is used as a clock by the SCXI-1120 to increment the MUXCOUNTER after each
conversion by the data acquisition board during scanning. This signal is referred to as
SCANCLK. See Chapter 3, Theory of Operation, for a description of MUXCOUNTER.
• Pin 43 is a reserved digital input.
The following specifications and ratings apply to the digital I/O lines.
Absolute maximum voltage
input rating 5.5 V with respect to DIG GND
Digital input specifications (referenced to DIG GND):
VIH input logic high voltage 2 V minimum
VIL input logic low voltage 0.8 V maximum
II input current leakage ±1 µA maximum
Digital output specifications (referenced to DIG GND):
VOH output logic high voltage 3.7 V minimum at 4 mA maximum
VOL output logic low voltage 0.4 V maximum at 4 mA maximum