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Chapter 5
Digital I/O Features
This section describes the following digital I/O features of the DT9850 Series boards:
• Digital I/O lines
• Resolution
• Interrupts
• Operation modes
Digital I/O Lines
DT9850 Series modules support eight dedicated digital input lines through the digital input
(DIN) and eight dedicated digital output lines through the (DOUT) subsystem.
By default, the digital input signals are floating when unwired. You can configure the state of
the digital input signals to be pulled up (high value) or pulled down (low value) when they
are unwired using the Digital I/O Termination Select pin (TB1, pin 19). Refer to
wiring information.
For digital input operations, you can specify the digital input line to read using either a
single-value or continuous digital input operation. For digital output operations, you can
specify the digital output line to update using a single-value operation. Refer to
more information on digital I/O operation modes.
On power up or reset, no digital data is output from the module.
Resolution
All DT9850 Series modules support a digital I/O resolution of 8 bits. This resolution is fixed
and cannot be changed in software.
Interrupts
The DT9850 Series modules can generate an interrupt when digital input line 0 to 6 of the
digital input port 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 module.
You enable the interrupts on a line-by-line basis during when you configure the driver; refer to
page 27
Note: To use the interrupt-on-change feature, you must configure the digital input lines for
either pull up or pull down, or you will see noise on the input lines; refer to
information. Digital input line 7 of the digital input port cannot generate an interrupt
Use software to determine which digital line changed state; refer to
information.
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