PiXtend eIO Hardware Manual
Connection Notes
The following diagram illustrates the connection of different signal sources to a digital
input.
The digital inputs are always logic "0" / "low" levels when idle (e.g., no voltage applied - no
connection). The inputs have a ground reference (pull-down), which prevents an undefined
state ("floating input").
With the digital inputs, a wide variety of sensors, switches and push-buttons can be
evaluated. The input voltage at the inputs can be in the range of 3.3 V to 30 V. In order to
cover this large area, a jumper was provided for each input, with which can choose
between two voltage ranges (adjustment of the switching level).
The pin headers on which the jumpers can be inserted are located behind the terminals of
the digital inputs on PiXtend eIO. Each two pins of the pin header are associated with an
input. The first two pins (from left to right) belong to DI0, the two subsequent DI1, and so
on.
The jumper short-circuits the two pins, adjusting the input circuit to the other input voltage
range.
By default, PiXtend eIO is delivered in the 24 V range (12 / 24 V) - no jumper is inserted.
With the jumper plugged in, the input is changed to the 5 V range (3.3 / 5 V).
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Figure 36: Principle circuit diagram: connection of the digital inputs
