Data Translation DT9835, User Manual

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Chapter 2
10
Digital I/O Lines
The DT9835 board supports 64 shared digital I/O lines. These lines
are organized as eight digital banks (banks 0 to 7)), each containing
eight digital I/O lines (lines 0 to 7).
The DT9835 board also supports 32 dedicated digital input lines.
These lines are organized as four banks (banks 8 to 11), each
containing eight digital input lines (lines 0 to 7).
You access the digital inputs through the digital input (DIN)
subsystem and the digital outputs through the digital output (DOUT)
subsystem.
The inputs are pulled up to +5 V through a 100 k
Ω
resistor. You can
choose to debounce the inputs using the Open Layers Control Panel.
When debounce is selected, a debounce delay of 5 ms occurs before a
change is passed through the digital filter on the module. When
debounce is not selected (the default configuration), a delay of less
than 1 ms occurs. Refer to the DT9835 Getting Started Manual for more
information.
Outputs are open collectors with a 100 k
Ω
resistor connected to the
internal is5 V. All outputs are diode-protected for back EMF
voltages typically seen when driving relays. The output stage latches
are normally powered by the module. However, you can externally
power the +5 V output so that the digital outputs retain their current
values when the module is powered down.
Note: +5 V output is available only when one of the subsystems is
activated, which, in turn, activates power to the module.
The DT9835 provides enough current to drive only one LED per
output line on the STP100 screw terminal panel at a time. An LED
turns on when the output is low.