Chapter 4
Programming
© National Instruments Corporation
4-31
AT-DIO-32F User Manual
CNTR2 Register (REQ2 Generator)
The CNTR2 Register contains eight bits that are used to load a value into Counter 2 or to read
back the value of Counter 2. The CNTR2 Register can be used as an 8-bit register or as a 16-bit
register by two successive write/read operations.
Address:
Base a 1A (hex)
Type:
Read-and-write
Word Size:
8-bit
Bit Map:
7
6
5
4
3
2
1
0
CNTR2B7
CNTR2B6
CNTR2B5
CNTR2B4
CNTR2B3
CNTR2B2
CNTR2B1
CNTR2B0
Bit
Name
Description
7-0
CNTR2B<7..0>
Counter 2 Load/Read Bits.
Writing a data value to these bits loads the starting value into
Counter 2. Reading these bits returns the current count of Counter
2 or latched data for Counter 2. If the Counter Latch command or
the Read-Back command is used to latch the count or status of
Counter 2, reading these bits returns the latched information. The
latched data remains latched until it is read.
If multiple Latch commands or Read-Back commands are issued
before the latched data is read, only the data from the first Status
Latch command and the first Counter Latch command are latched;
all commands after the first are ignored. If 16-bit data is latched,
the first read from this register returns the least significant byte,
and the second read returns the most significant byte. If status and
count information are both latched, the first read to this register
returns the status byte, and the next one read for 8-bit mode, or two
reads for 16-bit mode, returns the count bytes, regardless of the
order in which the information was latched.
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