© National Instruments Corporation
4-1
SCXI-1120 User Manual
Chapter 4
Register Descriptions
This chapter describes in detail the SCXI-1120 Module ID Register, the Configuration Register,
the Slot 0 registers, and multiplexer addressing.
Note: If you plan to use a programming software package such as NI-DAQ, LabWindows, or
LabVIEW with your SCXI-1120 board, you do not need to read this chapter.
Register Description
Register Description Format
This register description chapter discusses each of the SCXI-1120 registers and the Slot 0
registers. A detailed bit description of each register is given. The individual register description
gives the type, word size, and bit map of the register, followed by a description of each bit.
The register bit map shows a diagram of the register with the MSB shown on the left (bit 15 for a
16-bit register, bit 7 for an 8-bit register), and the LSB shown on the right (bit 0). A rectangle is
used to represent each bit. Each bit is labeled with a name inside its rectangle. An asterisk (*)
after the bit name indicates that the bit is inverted (negative logic). The Module ID register has a
unique format and is described in the Module ID Register section.
In many of the registers, several bits are labeled with an X, indicating don't care bits. When you
write to a register, you may set or clear these bits without effect.
SCXI-1120 Registers
The SCXI-1120 has two registers. The Module ID Register is a four-byte, read-only register that
contains the Module ID number of the SCXI-1120. The Configuration Register is a 16-bit,
write-only register that controls the functions and characteristics of the SCXI-1120.
