Lowrance electronic M68I User Manual

Pub. 988-0152-061

Addendum I

Additional Instructions for

Lowrance M68i S/Map

Your sonar/GPS unit, the M68i, functions exactly like the M68 de­scribed in the manual provided (part 988­M68i contains a communications port for NMEA 0183 output. The in­structions for connecting data cables and setting up the communica­tions port appear in this addendum. The back page also includes a cor­rection note for an error in the M68 manual.

NMEA 0183 Cable Connections

NMEA is a standard communications format for marine electronic
equipment. The M68i 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 M68i 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 M68i 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 M68i uses the yellow wire to transmit
and the black shield wire for signal ground.

0152-031). In addition, the

NOTE:

Some VHF radios, such as the popular Uniden
els which require use of an additional diode and resistor built into the
M68i 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 Dia-
gram 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 dia-

1



brand, have input lev-

gram 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
M68i. (You'll notice the M68i'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 pre-

stripped wires of the M68i'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
M68i data cable's yellow wire, and the radio's Ground/Shield wire to the
M68i 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.

Com port

to M68i

Yellow (Transmit)

Shield (Ground)

Com port wiring to transmit NMEA information

to a Uniden or similar VHF radio or other device.

NMEA Wire (Receive) or NMEA +

Ground/Shield or NMEA –

To Uniden

radio or other

device

2

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 M68i data cable.

You will notice near the end of the cable a segment protected with black
heat-shrink. To connect the M68i to a true RS-232 radio, first remove the
Uniden adapter segment of the cable as shown in the following figures.

3

k

(

)

(

)

For Wiring Diagram B installations, remove the Uniden adapter seg-

ment at the end of your data cable as shown at left. Snip off the end of

the cable protected by the black heat-shrink. At right, we have used

clear heat-shrink for clarity, so you can see the diode and resistor pro-

tected within. Remove this portion of the cable.

After you've removed the adapter segment, use wire pliers to expose the
ends of the five remaining wires in the cable. Cut off the black, blue and
white wires, then seal their ends with electrical tape.

Blac

Blue

White

Yellow

Bare wire

shield

After removing the adapter segment, prepare to connect by removing

and taping off unneeded wires. Strip the end of the yellow wire.

transmit

Cut black, blue
and white.

Strip about 1/4-inch (6.35 mm) of insulation from the yellow wire, then
follow the preceding wire nut and taping instructions to connect the
wires from the radio or other device.

If you're using a true RS-232 radio or other device, connect its (+) Re­ceive wire to the M68i data cable's yellow wire and its ground or (–) Re­ceive wire to the M68i data cable's bare shield wire.

Com port

to M68i

Yellow (Transmit)

Shield (Ground)

(+) Receive or Receive

(–) Receive or ground

To another

NMEA device

Com port wiring to transmit NMEA information

to another standard NMEA-compatible device.

4

When the data cable is connected to your VHF radio, all you have to do
is plug it into the sonar/GPS unit. Attach the data cable's plug to the
accessory socket on the right side of the back of your unit's case.

Communications Port Activation

Now that you have your devices connected, here's how to make them
communicate. This unit can connect to either an accessory such as a
speed or temperature sensor or a NMEA 0183 data cable. In order to use
the Communications Port for NMEA data, you first need to activate
NMEA 0183 Output.

Press

MENU|MENU|↓ to ENABLE NMEA 183 OUTPUT|ENT| ← to YES|ENT.

Enable NMEA command on the unit's Main Menu

Communications Port Configuration

Once NMEA 0183 Output has been enabled from the Main Menu, the
Com Port command appears in the System Setup Menu. This command
opens a menu that allows you to configure the communications port.

Menus for changing Com Port settings.

5

If you need additional assistance in configuring the unit to communicate
with another device, consult the factory; customer service phone num­bers are in the back of the unit's manual. To set Com Port Configuration:

1. Press

2. Press ↓ to

MENU|MENU|↓ to SYSTEM SETUP|ENT.

COMMUNICATIONS PORT|ENT.

A menu appears with a drop-down Baud Rate selection box highlighted.
The menu also contains an on/off checkbox to activate NMEA Output,
and a button that activates the Configure NMEA command (described
in the following section).

To set Baud Rate:

With the Baud Rate box selected (the title bar should be highlighted in
blue, see the middle figure above), press

ENT. A drop-down list appears,

showing available baud rates. Select the one that matches the baud
rate on your VHF radio, and then press

To activate NMEA Output:

ENT.

From the Communication Ports menu, press ↓ to highlight NMEA Out­put. Press

ENT to check (turn on) or uncheck (turn off) the NMEA Out-

put checkbox.

To exit the Communication Ports menu, press

EXIT|EXIT|EXIT.

Configure NMEA

Once in the Communication Ports menu, you can configure the unit to
use specific NMEA sentences. (The default setting has all NMEA sen­tences turned on.) Press ↓ to

CONFIGURE NMEA|ENT.

NMEA Sentences selection menu.

6

A menu appears showing the prefixes of the available NMEA sentences.
A check mark next to a prefix means the prefix is in use. Use ↑ ↓ → ←
to select a prefix, then press
to check the box and turn a prefix on.)

NOTE:

The names of the NMEA sentences are abbreviated in this menu.
These are the functions of the various selectable prefixes:

• GLL transmits latitude and longitude of present position, time of

position fix, and status.

• GGA transmits time, position and fix related data.

• APB transmits autopilot information.

• RMC and RMB transmits navigation information messages.

• GSA and GSV transmits fix mode, DOP values and satellites in

view information.

• DBT transmits the depth below the transducer.

• DPT transmits the depth

• MTW transmits the water temperature.

4. When the desired prefixes are checked or unchecked, press

EXIT|EXIT|EXIT|EXIT to return to the previous page.

ENT to turn off the prefix. (Press ENT again

Compatibility With Various VHF Radios

The Digital Selective Calling (DSC) feature in marine radios is rela­tively new technology. The U.S. Coast Guard, for example, imple­mented its first DSC-capable systems in Atlantic City, N.J. and Chinco­teague, VA in September, 2003. However, the entire U.S. DSC rescue
system won't be operational until Sept. 30, 2006.

As more marine electronics manufacturers enter this growing market, other
connectivity issues with your unit may appear. You can check for known
compatibility issues by visiting our web site, www.lowrance.com. Look in
the Manuals section for updated documents for your sonar/GPS unit.

7

Correction

On page 69 of the M68 manual (part 988-0152-031), step 1 for entering
Ice Machine mode is incorrect. It should read as follows:

To enter the IceMachine mode:

1. From the Full Sonar Chart page, press
switch to the normal Flasher page.

PAGES|↓ to FLASHER|EXIT to

This addendum supplements the manual M68, part number 988-0152-031.

Pub. 988-0152-061 © Copyright 2004

All Rights Reserved

Printed in USA 022704 Lowrance Electronics, Inc.

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