Advantech AIIS-1882, User Manual

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AIIS-1882 User Manual 16
3.2 Digital Output
The AIIS-1882 has digital output function. The following sections describe the digital
output update/generation mechanism. For detailed specification of the functions.
refer to Appendix A.
3.2.1 Static Digital Output Update
With static digital output update, the digital output state is updated only when the soft -
ware sends a “write static digital output sample” command. The digital output state
remains unchanged at other times. This is shown in Figure 3.19.
Figure 3.7 Static digital output update.
3.3 PWM Lighting Output Control
The lighting control leverages a PWM (Pulse Width Modulation) mechanism. A pulse
waveform with specified high period (tHIGH) and low period (tLOW) is output at
counter output terminal as shown in Figure 3-6.
Figure 3.8 Pulse width modulation output.
The lighting intensity is controlled by PWM high period. For example, in the same
PWM cycle period 100ms, setting 100ms as high drives the lighting to maximum
intensity, 0ms on the other hand, turns the lighting off. Figure 3-7 describes the rela -
tion between duty cycle and lighting intensity percentage. With duty cycle of 25%, the
ON period is 25% of the PWM cycle, that results in 25% lighting intensity. It is the
same way when the duty cycle is set to 50% or 75%.