HyQuest Solutions iRIS Under Cover, User Manual

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Installation
multiple pulses caused by contact bounce. The debounce jumpers are positioned in the centre of the PCB. The picture
below shows the links in their default positions.
Figure 8 – Digital Input Debounce Links
Fit the jumper for mechanical switching at up to 20 Hz. In this mode the input is normally pulled up to 12 V through a 10
kΩ resistor providing a wetting current of approximately 1.2 mA. A 100 nF capacitor is also fitted across the input to
provide limited hardware debounce, preventing false triggering due to contact bounce.
Remove the appropriate jumper for electronic switching at up to 5 kHz. In this mode the input is normally pulled up to 5
V through a 57 kΩ resistance, providing a wetting current of approximately 100 µ A. When DIO is used as an input the
debouce circuit is permanently connected to the input pin.
Figure 9 – Digital Input Circuit
Important note!
In almost all installations where an iRIS is connected in parallel with other equipment to share a common
pulse input (e.g. from a flow meter), there has not been a detrimental effect, as the iRIS inputs present a
relatively high impedance to the circuit. However, in the event that connecting an iRIS does cause pulse