51 PCIE-1816_1816H User Manual
Appendix B Operation Theory
B.3 Digital Input/Output Operation
The PCIE-1816/1816H supports 24 digital I/O channels. You can use each byte as
either an input port or an output port by configuring the corresponding parameter;
and all four channels of the byte have the same configuration.
You do not need to specify the clock source or trigger source. To output the data, you
just need to write it to the digital output channel directly. In the same way, you can
directly read back data from digital input channel. The default configuration after
reset sets all the digital I/O channels to logic-low so users don’t need to worry about
damaging external devices during system start up or reset.
B.4 Counter Input and PWM Input/Output
PCIE-1816/1816H offer two 32-bit counters inputs which can perform event counting,
frequency measurement and pulse width measurement.
Counters on PCIE-1816/1816H have a counter value match interrupt function. When
this interrupt function is enabled, an interrupt signal will be generated if the counter
value reaches a pre-set counter match value. The counter will continue to count until
an overflow occurs, then it will go back to its reset value zero and continue the count-
ing process. A user can set each individual counter channel to count either falling
edge (high-to-low) or rising edge (low-to-high) signals.
Except measurement functionality, counter input channels can combine with PWM
output channels to generate single pulse, pulse train or PWM (pulse-width modu-
lated) output signal. A pulse-width modulated waveform is created when the High
and Low periods of a periodic rectangular signal are varied. Using PCIE-1816/
1816H, user can individually set each PWM channel’s High and Low periods for from
2 to (2
32
-1) units (1 unit = 50 ns), depending on his needs.
1. Event Counter Connection
PCIE-1816/ 1816H built-in counter can calculate how many pulse are sent into
the input channel.
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