Chapter 4
Register Descriptions
© National Instruments Corporation
4-9
SCXI-1100 User Manual
FIFO Register
The FIFO Register adds entries to the Slot 0 FIFO. The FIFO contains the Slot 0 scan list. Each
entry contains a slot number to be accessed, and a count number to determine the number of
samples to be taken from that slot. To write to the FIFO Register, follow the procedure given in
the Register Writes section in Chapter 5, Programming, using 14 as the slot number and writing
16 bits to the FIFO Register. The register shifts in the data present on the MOSI line, bit 7 first,
when the Slot-Select Register selects Slot 14. Consecutive writes to the FIFO Register create the
Slot 0 scan list. Each write creates a new entry at the end of the scan list. The maximum number
of entries is 256. To clear the FIFO of all entries, clear the HSRS* bit in the HSCR.
Type:
Write-only
Word Size:
16-bit
Bit Map:
15
14
13
12
11
10
9
8
X
X
X
X
X
MOD3
MOD2
MOD1
7
6
5
4
3
2
1
0
MOD0
CNT6
CNT5
CNT4
CNT3
CNT2
CNT1
CNT0
Bit
Name
Description
15-11
X
Don't care bits – Unused.
10-7
MOD<3..0>
Module Number – The value of these bits plus one
determines the number of the slot to be accessed for this
scan entry. For example, to access Slot 6, MOD<3..0>
would be 0101.
6-0
CNT<6..0>
Count – The value of these bits plus one determines how
many samples are taken before the next scan list entry
becomes active. A value of zero corresponds to one sample
and a value of 127 corresponds to 128 samples.
