Vansco VMM3120, User Manual

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User Guide 59
Application Examples
9.5. Using one Analog Input as Two Digital Inputs
The VMM3120 allows you to use one analog input as two digital inputs, which is
useful in reducing harness lead or if you are running out of digital inputs in your
system.
To do this, you would connect the analog input to a single pole, double throw
(SPDT) switch.
Note: You will need to write your application logic to act according to the
voltage value readings provided by the analog input. Refer to the appropriate
help file, or contact your Parker Vansco Account Representative for more
information.
When making the connection, ensure there is a voltage difference between the
two pins on the SPDT switch. This can be done by

enabling the internal pull-up resistor on the analog input (done through
software)

adding a resistor to one of the pins on the SPDT switch.
The following shows how to connect an analog input to a SPDT switch:
Internal to product
Analog Input
VBAT
3.3 kohm
3.3 kohm
Figure 28: Connecting an analog input to an SPDT switch