Theory of Operation
Chapter 3
SCXI-1162 User Manual
3-4
© National Instruments Corporation
Table 3-1. SCXIbus Equivalents for the Rear Signal Connector
Rear Signal Connector
Signal
SCXIbus Equivalent
SERDATIN
MOSI
DAQD*/A
D*/A
SLOT0SEL*
INTR*
SERCLK
SPICLK
SERDATOUT
MISO
You must set jumper W6 to position DIO or MIO.
When the rear connector is jumper configured for serial communication with the SCXIbus, the
SCXI-1162 module converts the data acquisition board signals to open-collector signals on the
backplane of the SCXI chassis. For the data acquisition board to talk to a slot, the board must
first assert the SS* for that slot. You do this by asserting INTR* low, writing a 16-bit number
over MOSI corresponding to the desired slot (and chassis if you are using an SCXI-1001
chassis), and then releasing INTR* high. At this point, the SS* of the desired slot is asserted low
and the data acquisition board can communicate with the module in that slot according to the SPI
protocol.
Digital Interface
Figure 3-3 shows a diagram of the SCXI-1162 and SCXIbus digital interface circuitry.
RESET*
MISO
SPICLK
INTR*
D*/A
MOSI
SS*
SCXIbus
SERDA
TIN
DAQD*/A
SLOT0SEL*
SERCLK
Rear Connector
Configuration /
Routing
SCXI Digital
Interface
Buffered Digital
Signal Controls
Buffered
Serial Data
Address
Handler
and
Registers
Rear Connector
Optically Isolated Inputs
SERDA
T
OUT
Figure 3-3. Digital Interface Circuitry Block Diagram
