Garmin GNX 120 7_inch Guida Di Riferimento

NMEA 2000 Fundamentals

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When the voltage drop formula is applied to this example, we see 

that the voltage drop is greater than 3.0 Vdc, so this NMEA 2000 

network will not function correctly when powered at the end.

Voltage Drop = 0.053 × (2 + 20 + 10 + 6) × (4 + 5 + 7) × 0.1 = 3.22 Vdc

This NMEA 2000 network must be redesigned with the power connected to the center of the network in order to function correctly.

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When the NMEA 2000 network is redesigned with the power source in the center, you calculate the voltage drop in both directions. If the 

T-connector to which you connect the power source is connected directly to another T-connector (as shown in this example), use the LEN from 

that device as part of the calculation for both directions.

Voltage Drop Left = 0.053 × (2 + 20 + 2) × (4 + 5) × 0.1 = 1.145 Vdc

Voltage Drop Right = 0.053 × (2 + 10 + 6) × (5 + 7) × 0.1 = 1.145 Vdc

When the voltage drop formula is applied to both the left and right 

sides of the power source in this example, we see that the voltage drop 

is less than 3.0 Vdc on each side, so the NMEA 2000 network will 

function correctly.

  Note: The equation and examples provide conservative estimates for calculating voltage drop.