Register Descriptions
Chapter 4
SCXI-1100 User Manual
4-6
© National Instruments Corporation
Slot 0 Register Descriptions
Slot 0 has three registers. The Slot-Select Register is a 16-bit write-only register that determines
with which slot the data acquisition board speaks when SLOT0SEL* is released high. With the
SCXI-1001 chassis, the Slot-Select Register also determines in which chassis the desired slot is.
The FIFO Register is a 16-bit write-only register that stores the Slot 0 scan list that determines
the chassis scan sequence. The Hardscan Control Register (HSCR) is an 8-bit write-only register
that sets up the timing circuitry in Slot 0. The Slot-Select Register is written to over the
SLOT0SEL* line. Write to the HSCR and the FIFO Register as if they were registers on
modules in Slots 13 and 14. Maintain software copies of the Slot-Select Register, HSCRs, and
all the Slot 0 scan lists that correspond to the writes to FIFO Registers.
If you are using multiple chassis, it is important to understand the architectural differences of the
Slot-Select Register as compared to the HSCR and the FIFO Register. Although each chassis
has its own physical Slot-Select Register, all are written to at the same time. The jumper settings
in Slot 0 of a chassis determine with which chassis number Slot 0 is identified. From the
software perspective, only one Slot-Select Register exists in a system composed of multiple
chassis. The HSCR and FIFO Register, on the other hand, are unique to each chassis, and you
must program them separately.
