Maretron N2KMeter User manual

N2KMeter®
NMEA 2000®Diagnostic Tool
User’s Manual
Revision 1.3
Maretron Manual Part #: M000701

N2KMeter User’s Manual
Page i Revision 1.3
Table of Contents
1General ..............................................................................................................................2
1.1 Introduction................................................................................................................2
1.2 Features.....................................................................................................................2
2Installation..........................................................................................................................2
2.1 Unpacking the Box.....................................................................................................2
3Essentials...........................................................................................................................3
3.1 Batteries.....................................................................................................................3
3.2 AutoSearch Mode......................................................................................................3
3.3 NMEA 2000®Cable ...................................................................................................3
4How to use this manual......................................................................................................4
5Using the N2KMeter...........................................................................................................5
5.1 Viewing Measurements..............................................................................................5
5.2 Display Lock ..............................................................................................................5
5.3 Resetting Min/Max Measurements.............................................................................5
6Display ...............................................................................................................................6
7Bus Errors (Switch Position 2)............................................................................................7
8Bus Traffic (Switch Position 3) ...........................................................................................9
9Bus Power (Switch Position 4).........................................................................................11
9.1 What’s a Transient?.................................................................................................11
10 Shield Voltage (Switch Position 5) ...................................................................................13
10.1 About NMEA 2000®Shield Voltage .........................................................................13
11 CAN Primer......................................................................................................................15
12 Common Mode Voltage (Switch Position 6).....................................................................17
12.1 What is Common Mode Voltage? ............................................................................17
13 NET-H/L Differential V Recessive (Switch Position 7)......................................................19
13.1 Importance of NET-H/L Differential V Recessive Measurement..............................19
13.2 What is “recessive?” ................................................................................................20
14 NET-H/L Differential V Dominant (Switch Position 8).......................................................21
14.1 What is “Dominant”? ................................................................................................21
15 CAN Signal Thresholds (Switch Positions 9-12) ..............................................................23
16 NMEA 2000®Glossary.....................................................................................................24
17 Switch Settings.................................................................................................................25
18 Certifications ....................................................................................................................25
19 Cables..............................................................................................................................26
20 Hexadecimal to Decimal Conversion Table......................................................................27
21 Specifications...................................................................................................................28

Revision 1.3 Page 1
Revision History
Rev.
Description
1.2
Updated Company Address
1.3
Changed cable part number

Page 2 Revision 1.3
1 General
1.1 Introduction
Congratulations on your purchase of the Maretron N2KMeter. The N2KMeter is a diagnostic tool
for NMEA 2000®networks that allows users to validate NMEA 2000®network compatibility and
operations during installation of a device or complete system, and diagnose possible network
flaws or failures that occur on an operational network.
Please read carefully and follow these instructions for usage of the Maretron N2KMeter in order
to ensure optimal performance and accurate measurements.
1.2 Features
The N2KMeter uses a patented integrated intelligence technique to summarize multiple NMEA
2000®network operational variables into a single health index. To a service technician, it's a
"guru-in-a-box", providing a detailed reading of network performance. It summarizes NMEA
2000®network health by displaying a happy face icon ( ), indicating a healthy network; a sad
face ( ), indicating a serious problem; or a neutral face ( ), indicating nominal performance (a
good indication to repair things before they actually fail). The N2KMeter then walks the user
through each fault condition and its source, or it can record key operating parameters for offline
review.
Faults that can be detected by the N2KMeter include
Opens and Shorts
Incorrect Topology
Bad Nodes
Bad Termination
Improper Shield Connection
Intermittent Problems
Excessive Scan Rate
Common Mode Voltage
2 Installation
2.1 Unpacking the Box
When unpacking the box containing the Maretron N2KMeter, you should find the following items.
1 –N2KMeter Diagnostic Tool
1 –NMEA 2000®Adapter Cable
1 –N2KMeter User’s Manual (Includes Warranty Statement and Registration)
2 –“AA” Alkaline Batteries
If any of these items are missing or damaged, please contact Maretron.

Revision 1.3 Page 3
3 Essentials
3.1 Batteries
The N2KMeter requires 2 “AA” alkaline batteries for viewing measurements offline. The
N2KMeter must be plugged into a powered network to get most measurements. The N2KMeter
will run off NMEA 2000®network power, even without batteries installed. Remember to install
batteries if you plan to use the Lock and offline viewing features.
3.2 AutoSearch Mode
AutoSearch mode saves you time by finding the network measurements that exceed acceptable
limits. It works by examining all measurements and then pinpointing any that exceed or are close
to specified limits. For each problem measurement, the N2KMeter indicates the measurement’s
switch position number in the upper left corner of the display. Rotate the selector switch to the
indicated setting to view related measurements. To use AutoSearch, follow these simple
instructions:
1. Make sure the Lock switch is in the “Run” position and turn the selector switch to
AutoSearch
2. If you see , all measurements are within limits.
3. If you see or , then read the display like this ...
“Switch setting <Setting #>, <MIN> or <MAX> and/or <P-P> is close to or Exceeds
the spec limits.”
Then press and repeat the process for the next bad/marginal value. To get more detail, turn
the selector switch to the indicated position and use the buttons , , and to access related
measurements.
3.3 NMEA 2000®Cable
NMEA 2000®cable has five wires inside. Each has a specific purpose that is referenced in this
manual.
NET-L (blue)
(messages)
NET-H (white)
(messages)
Shield
NET-C (black)
(ground)
NET-S (red)
(power)

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4 How to use this manual
The N2KMeter has a large selector switch with 12 different positions. For each switch position,
you will find a section in this reference manual explaining the measurements available and
suggested actions and/or remedies if your network is not healthy. In each section, you’ll find a
diagram showing the display, button push and display reading description as shown below.
NOTE: Node Addresses are displayed by the N2KMeter in hexadecimal notation. Some network
design specifications may refer to node addresses with decimal notation. Please refer to the
conversion table in Section 20 on page 27 to convert between the two notations.
The measured value exceeds the positive or
negative input range.
Sign indicates negative over-range
No measurement taken (see additional details for
specific measurements).
Displays the maximum frame rate per
second on the network since the
N2KMeter was plugged in or reset.
Viewing
measurement
for this device
(Node
Address).
You can view this measurement for each active device by
pressing the or buttons.
Pressing and at the same time displays the overall
network measurement again.
LCD Display
The minimum shield voltage recorded
since the N2KMeter was plugged in
or reset is -1.5V.
# of times to push the advance button after moving the
selector switch to display this measurement.
Description
Push the Advance button

Revision 1.3 Page 5
5 Using the N2KMeter
5.1 Viewing Measurements
Each selector switch position accesses a different bus measurement, and each supports several
different measurement types.
Pressing cycles the display through the different measurements available at each switch
position.
Some measurements allow a detailed view for each Node Address. Press OR to cycle
through the active Node Addresses. Press AND together to return to the overall network
view.
5.2 Display Lock
To lock measurements for offline viewing, move the lock switch to the position. To erase stored
values and restart bus analysis move the lock switch to “Run”.
Stored values are retained indefinitely, providing the lock switch is left in the position, and the
batteries are good - even if the meter is turned off.
5.3 Resetting Min/Max Measurements
The N2KMeter is reset (Min/Max and other stored measurements cleared) when the Lock switch
is moved to the "Run" position, and when the power switch is turned On while the Lock switch is
in the "Run" position.
You may reset stored measurements by either turning the meter off and on again, or by moving
the Lock switch to and back to “Run”.
Pushbuttons
Next Measurement
Next Node Address
Previous Node Address
Return to Network View (push at
the same time)
Selector Switch
LCD Display

Page 6 Revision 1.3
6 Display
The N2KMeter LCD display includes a large 3-digit display as well as 17 other indicators that
are shown in the following diagram.
1 Network Node Address (node #) or N2KMeter switch setting number (AutoSearch)
2 Display Locked indicator (“lock” switch is on)
3 Measurement displayed is acceptable
4 Measurement displayed is marginal
5 Measurement displayed is unacceptable
6 Battery low –stored measurements may be lost
7 125 Kbaud network activity detected
8 250 Kbaud network activity detected
9 500 Kbaud network activity detected
10 Measurement unit is % bandwidth
11 Measurement unit is errors / messages per second
12 Measurement unit is volts
13 Measurement displayed is in thousands (kilo)
14 Measurement displayed is a maximum value
15 Measurement displayed is a minimum value
16 Measurement displayed is a peak-to-peak value
17 Displayed when viewing measurements for a particular Node Address. Not displayed
in AutoSearch mode when the value shown in the top left corner is a switch position.
NOTE: If none of MIN, MAX or P-P is shown then the value displayed is a “live” measurement
or the most recent “Live” measurement if the “lock” switch is on.

Revision 1.3 Page 7
7 Bus Errors (Switch Position 2)
The N2KMeter tracks network data transmission errors in real-time, and lets you know if the
error rate is acceptable , marginal , or unacceptable . Any error rate greater than zero is
undesirable (although your network may still function since CAN automatically retransmits after
errors). An error rate greater than 10/s indicates a problem that should be investigated.
The N2KMeter uses unique technology to accurately determine which node was attempting to
transmit when a bus error occurs.
Display What it means
NOTE: Node error measurements only include errors known to have occurred when the node is
transmitting. Frames with corrupt ID fields, andframes that cannot be attributed to specific nodes
are not included in node measurements. It is common for the sum of per-node results to be less
than the overall network values.
Thresholds
Error Rate High Fault 15 /s
Error Rate High Warn 1 /s
Maximum bus error rate on the whole
network since N2KMeter was
connected or reset.
Minimum bus error rate on whole
network since N2KMeter was
connected to the network or reset.
Incremental error count on the entire
network since the N2KMeter was
connected or reset.
Real-time error rate of 14
errors/second

Page 8 Revision 1.3
What to do when you see or :
Press or to identify the device(s) with higher error rates than other nodes.
calculate the ratio of error rate to frame rate of suspect nodes and check for above
average ratios. Devices with above average error ratios should be investigated
further.
Check the other measurements and investigate the suspect device(s) for faults
consistent with the observed symptoms.
Some techniques you can use are:
oReplace the device and/or cabling.
oTemporarily remove the device from the network to see if the errors cease.
If you suspect an intermittent cable or connector, shake, bend or twist the suspected
cable and/or connector while watching the error rate for changes (up or down).
Excessive cable lengths and faulty nodes can cause errors in the transmissions of some/all other
nodes. Do not assume that the node(s) with the highest error rate is faulty.
Bus Errors
deal with
these two
wires (NET-L
(blue)& NET-H
(white))