National Instruments SCXI-1120 - Manual (Page 53)

Theory of Operation Chapter 3
SCXI-1120 User Manual 3-6 © National Instruments Corporation
Digital Interface
Figure 3-3 shows a diagram of the SCXI-1120 and SCXIbus digital interface circuitry.
Digital
Interface
SCXIbus
Buffered Serial
Data
Buffered Digital
Signal Controls
SERDATIN
DAQD*/A
SLOT0SEL*
SERCLK
SERDATOUT
Rear
Signal Connector
MISO
SPICLK
INTR* D*/A MOSI
SS*
Figure 3-3. Digital Interface Circuitry Block Diagram
The digital interface circuitry is divided into a data acquisition section and an SCXIbus section.
The SCXI-1120 connects to the SCXIbus via a 4x24 metral receptacle and to the data acquisition
board via a 50-pin ribbon-cable header. The digital interface circuitry buffers the digital signals
from the data acquisition board and the SCXIbus and sends signals back and forth between the
data acquisition board and the SCXIbus.