Vansco VMM3120, User Manual

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User Guide 23
Inputs
To reduce ground level shift:

If there are more than 1 GND pins in the system, dedicate one of them to
sensors that have ground wires, and connect all sensor grounds to that system
ground pin.

Splice the other system ground inputs together in the vehicle harness (close to
the connector), to provide a better ground for the noisier low-side outputs and
digital circuits.
 Ensure the sensor’s ground connection is close to the system ground
connections. This will help ensure the signal remains within the digital
activation range of the input.
Note 1: The VMM3120 system ground inputs are rated for low-current
signals, which ensures the sensor’s ground is very close in voltage potential to
the system ground.
Note 2: Sensors that don’t have a dedicated ground wire are typically
grounded to the vehicle chassis through the sensor’s body.
The following shows a typical AC-coupled frequency input connection:
Internal to product
Sensor Ground
Variable Reluctance
Sensor
AC Coupled
Frequency Input
Figure 11: AC-coupled frequency input installation connections