Lowrance M56i Installation Instructions

Pub. 988-0152-051

Addendum I

Additional Instructions for

Lowrance M56i S/MAP

Your sonar/GPS unit, the M56i, functions exactly like the M56 described in the manual provided (part 988-0152-021). In addition, the M56i contains a communications port for NMEA 0183 output. The instructions for connecting data cables and setting up the communications port appear in this addendum.

NMEA 0183 Data Cable Connections

NMEA is a standard communications format for marine electronic equipment. The M56i can send information to any device that receives NMEA 0183 data. This allows the unit to work with VHF marine radios equipped with the Digital Selective Calling (DSC) distress call feature.

To send NMEA 0183 data, the M56i has one NMEA 0183 version 2.0 communication port. The com port can be used to send NMEA formatted data such as your current position.

The provided M56i data cable plugs into the accessory socket on the right side of the back of your unit's case. This socket can connect either an accessory such as a speed or temperature sensor or a NMEA 0183 data cable. The data cable ends in two wires that connect to your VHF radio or other NMEA device. The M56i uses the yellow wire to transmit and the black shield wire for signal ground.

NOTE:

Some VHF radios, such as the popular Uniden brand, have input levels which require use of an additional diode and resistor built into the M56i data cable. This is Wiring Diagram A, which is described on page 2. The majority of the DSC radios will work with the resistor and diode as provided by Lowrance Electronics.

A few other radio brands (and other electronic devices) that meet the NMEA 0183 standard won't need these adapters and you will have to remove the resistor and diode to make those work. This is Wiring Diagram B, which is described on page 3.

Consult your other device's owner’s manual, then read through all of the following instructions before you begin. Use the installation diagram most suited to your brand of radio or other device. If your device manual indicates an RS-232 connection (i.e., a computer), remove the

resistor and diode and connect using Wiring Diagram B. Most other connection types (TTL; NMEA + and NMEA –; differential) will require Wiring Diagram A.

Recommended Tools and supplies

Recommended tools for this job include: wire pliers or wire stripper and a wire cutter. Required supplies for this job include: two gray (18 gauge) or blue (16 gauge) wire nuts and electrical tape. Supplies are not included.

Wiring Diagram "A"

Begin by stripping the wire ends of the device you're connecting to the M56i. (You'll notice the M56i's data cable comes pre-stripped, with wire ends exposed.) Use a pair of wire pliers to strip about 1/4-inch (6.35 mm) of insulation from each of the radio's or other device's data wires.

Strip the ends of the VHF radio's data wires. Connect them to the prestripped wires of the M56i's data cable (shown right).

Twist the exposed wires together as shown in the following figures. If you're using a Uniden or similar radio, connect the radio's NMEA Wire to the M56i data cable's yellow wire, and the radio's Ground/Shield wire to the M56i data cable's black shield wire. If you're using another radio brand or NMEA device, see Wiring Diagram B instructions at the end of page 3.

Yellow (Transmit)	NMEA Wire (Receive) or NMEA +
Com port		To Uniden
to M56i Shield (Ground)	Ground/Shield or	NMEA – radio or other
		device

Com port wiring to transmit NMEA information to a Uniden or similar VHF radio or other device.

Twist the appropriate wires together, making sure that the exposed ends make good contact. Secure the wire ends with wire nuts, then wrap each wire nut securely with electrical tape to protect against moisture, as shown in the figure on the right.

After taping the wire ends individually, wrap the entire connection with electrical tape as shown. This will help protect from moisture and prevent the wires from breaking contact.

Wiring Diagram "B"

If your VHF radio or other device requires true RS-232, you will need to remove the diode and resistor built into the end of the M56i data cable.

You will notice near the end of the cable a segment protected with black heat-shrink. To connect the M56i to a true RS-232 radio, first remove the Uniden adapter segment of the cable as shown in the following figures.

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