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Wiring | GN70/MX610/MX612 Operator and Installation Manual
Terminating the CAN bus
The CAN bus must have a 120 Ohm terminator at each end of the backbone.
In a default GN70/MX61x system the CAN bus can be powered and terminated from the
junction box PCB, enabled by the micro switch.
- Set the switch to ON when the MX610JB board is at the end of the CAN bus
- Set the switch to OFF when the MX610JB board is used as additional power supply to the
CAN bus which already has correct termination.
Factory default setting of MX610JB terminator is OFF.
For location of the dip switch, refer to the illustrations inside the junction box unit.
A terminator in the other end of the CAN bus can be one of the following:
• A power cable with built in terminator (plug marked 120 ohm)
• A single terminator plug (marked 120 ohm)
Shield connection
It is required to use shielded cables to meet radio frequency interference requirements as
defined in the NMEA 2000 specification:
• The shield shall not be electrically connected within the interface to the electronic device
chassis or ground
• The shield shall be electrically continuous through the network connection
• The shield shall be connected to ground at a single point, normally the ship’s ground at the
source of network power
Power supply
¼ Notes:
• Wheelmark/US Coast Guard approved systems require a Power Failure alarm. In such
installations the GN70/MX61x and the MX610JB must be connected to different independent
power supplies.
• It is recommended to install an external on/off switch or circuit breaker for the Junction Box
power supply.
• Do not connect the power cable to the same terminals as the start batteries, drive units,
thruster or other high current products.
• If joining to an existing NMEA 2000 network or similar CAN bus network that has its own
power supply, use an NMEA 2000 Gateway to isolate the two power supplies.
Powering the CAN (N2K) bus
For larger systems additional power should be added at a central point in the backbone to
balance the voltage drop of the network. Additional power may be supplied by using an
MX610JB junction box or through a Micro T-Joiner.
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