Pub. 988-0152-061
Addendum I
Additional Instructions for
Lowrance M68i S/Map
Your sonar/GPS unit, the M68i, functions exactly like the M68 de-
scribed in the manual provided (part 988-0152-031). In addition, the
M68i contains a communications port for NMEA 0183 output. The in-
structions for connecting data cables and setting up the communica-
tions port appear in this addendum. The back page also includes a cor-
rection 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 format-
ted 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.
NOTE:
Some VHF radios, such as the popular Uniden brand, have input lev-
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
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
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.
Black
Cut black, blue
and white.
Blue
White
Yellow
(transmit)
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.
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 (+) Re-
ceive wire to the M68i data cable's yellow wire and its ground or (–) Re-
ceive wire to the M68i data cable's bare shield wire.
Yellow (Transmit)
Shield (Ground)
(+) Receive or Receive
(–) Receive or ground
Com port
to M68i
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 num-
bers are in the back of the unit's manual. To set Com Port Configuration:
1. Press MENU|MENU|↓ to SYSTEM SETUP|ENT.
2. Press ↓ to 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 ENT.
To activate NMEA Output:
From the Communication Ports menu, press ↓ to highlight NMEA Out-
put. 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 sen-
tences 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 ENT to turn off the prefix. (Press ENT again
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.
Compatibility With Various VHF Radios
The Digital Selective Calling (DSC) feature in marine radios is rela-
tively new technology. The U.S. Coast Guard, for example, imple-
mented its first DSC-capable systems in Atlantic City, N.J. and Chinco-
teague, 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
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 PAGES|↓ to FLASHER|EXIT to
switch to the normal Flasher page.
This addendum supplements the manual M68, part number 988-0152-031.
Pub. 988-0152-061
© Copyright 2004
All Rights Reserved
Lowrance Electronics, Inc.
Printed in USA 022704
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