The status byte returned if STA=0 is:
B7 B6 B5 B4 B3 B2 B1 B0
OUT NC RW1 RW2 M2 M1 M0
BCD
OUT:
Current state of counter output pin.
NC:
Null count. This indicates when the last count loaded into the counter register has
been loaded into the actual counter. The exact time of load depends on the
configuration selected. Until the count is loaded into the counter, it cannot be read.
RW1,
RW0: Read/Write
command.
M2, M1, M0:
Counter mode.
BCD:
BCD = 0 is binary mode, otherwise counter is in BCD mode.
If both STA and CNT bits in the readback command byte are set low and the RW1 and RW0 bits have
both been previously set high in the counter control register (thus selecting two-byte reads), then
reading a selected counter address location will yield:
1st Read:
Status byte
2nd Read:
Low byte of latched data
3rd Read:
High byte of latched data
After any latching operation on a counter, the contents of its hold register must be read before any
subsequent latches of that counter will have any effect. If a status latch command is issued before the
hold register is read, then the first read will read the status, not the latched value.
Manual 104-DIO-48E, 24E
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