Principles of Operation
59
Note:
When the resolution is greater than 8, the bit value represents the combined number
of digital I/O lines. For example, if the resolution is 32, digital I/O lines 0 to 7 of Port A are
represented as bits 0 to 7 of the digital value, digital I/O lines 0 to 7 of Port B are represented
as bits 8 to 15 of the digital value, digital I/O lines 0 to 7 of Port C are represented as bits 16 to
23 of the digital value, and digital I/O lines 0 to 7 of Port D are represented as bits 24 to 31 of
the digital value.
Interrupts
When using 8-bit resolution only, the DT330 Series boards can generate a PCI-bus interrupt
when any of the eight digital I/O lines corresponding to digital Port D (DIN element 3)
changes state. This feature is useful when you want to monitor critical signals or when you
want to signal the host computer to transfer data to or from the board. You enable the
interrupts on a line-by-line basis during DT330 driver configuration; refer to
page 27
for more
information.
Use software to determine which digital line changed state; refer to
page 60
for more
information.
Operation Modes
DT330 Series boards support the following digital I/O operation modes:
•
Single-value operations
– Use software to specify the DIN or DOUT subsystem, the
resolution, and a gain of 1 (the gain is ignored). Data is then read from or written to the
appropriate digital I/O lines.
Single-value operations stop automatically when finished; you cannot stop a single-value
operation.
Note:
Although single-value operations are the simplest to use, they do not allow you to
check the interrupt status.
16
Ports A and B, lines 0
to 15 combined
Element 0
Ports C and D, lines 0
to 15 combined
Element 2
24
a
Ports A, B, and C, lines
0 to 23 combined
Element 0
32
Ports A, B, C, and D,
lines 0 to 31 combined
Element 0
a. For 24-bit resolution, lines 24 to 31 are not used.
Table 9: Resolution, Digital I/O Lines, and Number of Subsystems
Resolution
Digital I/O Lines
DIN or DOUT Subsystem
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Summary of Contents for DT330 Series
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