NI UMI-7774/72 User Guide and Specifications
26
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The interface circuit is the same for the forward limits, reverse limits, and home inputs. As shown in
Figure 24, you can wire a sourcing output device, such as a PNP sensor, to the limit or home inputs. You
can use the isolated power (V
iso
) and isolated common (C
iso
) signals provided on the control connector
to power the limit home sensor.
Figure 24.
UMI-7774/72 Optically Isolated Sinking Input Interface Circuit and Connection to
Sourcing Output Sensor
You can also connect the limit and home inputs to a high-side switch. Figure 25 shows an example of
wiring the limit or home input to a high-side switch.
Figure 25.
UMI-7774-7772 Optically Isolated Sinking Input Interface Circuit and Connection to
High-Side Switch
Input
Vcc
UMI-7774/72
Current Limiter
PNP
(Sourcing)
Output Device
Viso
Ciso
V–
V+
Out
Out
Ciso
Digital
Input
Viso
Vcc
UMI-7774/72
High-Side
Limit Switch
Current Limiter
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