Plant Floor
Troubleshooting Guide

PUB00147R0
MARCH 2006
PUB00026R4

The ODVA Automotive Special Interest Group (SIG) is pleased to offer this document as atool for troubleshooting devices that have been implemented into a DeviceNet network as wellas the DeviceNet network itself.
The following individuals have been invaluable in putting this document together:Training Committee Members:
Matt Kuzel
Borisa Begic
James O’Laughlin
Erick Rudaitis
Michael Giroux

Huron Networks
InterlinkBT
SICK, Incorporated
SMC Corporation of America
WAGO Corporation

Automotive SIG Members:
Erick Rudaitis, Chairperson
Marie Sandor, Administration

SMC Corporation of America
SMC Corporation of America

Thomas Dwyer
Greg Irwin
Gil Jones
Frank Latino
Matt Kuzel
Borisa Begic
Gary Workman
Enrico DeCarolis
Anton Suarez
Dave VanGompel
James O’Laughlin
Ed Ingraham
Mike Johnson
Michael Giroux
Chuck Sammut

Bosch Rexroth
DaimlerChrysler
EATON Corporation
Festo
Huron Networks
InterlinkBT LLC
General Motors
Numatics, Inc.
OMRON Corporation
Rockwell Automation
SICK, Incorporated
Siemens
SOLA / Hevi Duty
WAGO Corporation
Woodhead

For more information regarding the ODVA, including the Automotive SIG, please refer to the
ODVA website at:www.odva.org

Plant Floor Troubleshooting Guide

DeviceNet Plant Floor Troubleshooting
Flowchart

See
Page 1(Suspected Network Error / Multi-Node Problem)

DeviceNet Plant Floor Troubleshooting
Flowchart

See
Page 11(Intermittent Failures)

DeviceNet Plant Floor Troubleshooting
Flowchart

See
Page 15(Single Node Problem)

Walking the Network

See
Page 19

Segmenting the Network to TroubleshootSee
Page 20

DeviceNet Network Checklist

See
Page 21

Start 1: DeviceNet Plant Floor Troubleshooting Flowchart(Suspected Network Error / Multi-Node Problem)

Are the DeviceNetscanner LEDs red(Bus off)?

Note any
diagnostic
information on
DeviceNet scanner
if available.

No

Yes

Turn Auxiliary and DeviceNet PowerOFF, Wait 10 seconds, Turn back ON.
Examine scanner LEDs

Are the DeviceNetscanner LEDs red(Bus off)?

No

Yes

Cycle System, Auxiliary andDeviceNet Power, Wait 10 seconds
Examine scanner LEDs

Are the DeviceNetscanner LEDs red(Bus off)?

No

Yes
See
Page 19

Review Walk the Network

Attach DeviceNet Diagnostic Tool

Go to
B

Go to
O

See
Page 2

See
Page 11

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 1

B
Was problem
found during the
network walk?

Yes

Done

No

Is there only one nodewith red Module (MS)or Network Status(NS) LEDs?

Yes

Go to
E

No

See
Page 4

Disconnect DeviceNet trunk cable from thecabinet with scanner module.
Attach terminating resistor. Turn off
DeviceNet power, wait 10 seconds, turnDeviceNet power back on.

Are the DeviceNetscanner LEDs red(Bus off)?

The bus off indication
should be gone anddiagnostics formissing nodes should
be displayed.
Yes

Check nodes and cabling insidecabinet.

No

Reconnect network.

Problem fixed?
Are there multiple
DeviceNet network
power supplies?

Yes

No

No
Yes

Disconnect supplemental power
supplies.

Go to
C
See
Page 3
DeviceNet Plant Floor Troubleshooting Guide

Go to
F

Go to
D

See
Page 5

See
Page 3
PUB00147R0

Done

Page 2C

Is V- of the power
supplies tied to V- ofDeviceNet?

Yes

Is V+ of the power
supplies wired
separately?

No

Yes

No

Wire V- of all power supplies together.
Reconnect trunk cable.

Wire V+ of all power supplies
separately.
Reconnect trunk cable.

Go to
F
See
Page 5Start

D

Are the nodes andcables okay?

Yes

No

Replace cable or node.

Replace scanner.

Reconnect network.

Reconnect network.

Go To
Start 1

Go to
Start 1

See
Page 1

See
Page 1

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 3

E
Disconnect node from network.
Turn Auxiliary and DeviceNet PowerOFF, Wait 10 seconds, Turn back ON.

Are the DeviceNetscanner LEDs red(Bus off)?

Note: Other nodes cancause a node to go offline.

No

Yes

Replace node.
Verify Baud Rate, Node Address and.EDS file information.

Replace drop cable.

Are the DeviceNetscanner LEDs red(Bus off)?

No

Done

Yes

Go to
F
See
Page 5

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 4

F
Note:
Changes such as cabling,
tools, firmware, nodes, etc.
Have any changes
been made to network
since last time worked
consistently?

Yes

Investigate changes
No

See
Page 23

Check Voltages
See Items 12, 13 & 14 in
DeviceNet Network Checklist

Go toStart 1
See
Page 1

Are DeviceNet
voltages correct?

Yes

Go to
K

No

See
Page 8Change power supply

Go to
G
See
Page 6

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 5G

Bus off condition
fixed?

Yes

Done

No

See
Page 21

Complete
DeviceNet Network
Checklist

Errors found andfixed?

Note: This will now takesome time. Check
1. Cables, 2. Node,
3. Segment, 4. Grounding
5. CAN transceiver shorted
6. Not 60Ω etc.

Yes

Done

No

See
Page 23

Check Voltages
See Items 12, 13 & 14 in
DeviceNet Network Checklist

Voltages OK?

Yes

Go to
I

No

See
Page 7Go To
H
SeePage 7

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 6

H

All cable
connections OK?

No

Fix cable connection
Yes

I
Go to
Start 1
See
Page 1

Attach DeviceNet diagnostic tool andmeasure CAN errors> 20
errors/second?

No

Go to
K

Yes

See
Page 21

See
Page 8Recheck for ground loops
using
DeviceNet Network Checklist

Problem found andfixed?

Yes

Done

No

Go to
J
See
Page 8DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 7

J
Replace power supply again in thecase that current power supply is alsobad.

Errors found andfixed?

Yes

Done

No

K
Divide network into two sections.
Connect section 1 and moveterminating resistor.

Network up?

No

Yes

Disconnect Section 1. Connect
Section 2 and move terminating
resistor.

Network up?

Troubleshoot other½ of the network

No

Isolate problem

Go to
M

Yes

Go to
L

See
Page 9See Page 9
DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 8

L
Checking forpotential network
load issues.

Replace scanner. Reconnect entire
network.

Bus off condition
fixed?

Yes

Done

No

Check for wiringand other nodes
within the scannercabinet.

Isolate problem
Check for issues in cabinet

Problem
SolvedYes

No

M
Rewalk network looking for stressedcables (e.g. bend radius too tight, tiewrapped where it causes failure)

Any shorts oropens?

No

Go to
N
See Page 10
DeviceNet Plant Floor Troubleshooting Guide

Yes

Fix problem

Go toStart 1
See
Page 1
PUB00147R0

Page 9

N
Disconnect all nodes, add one node ata time until network communication
fails. Determine node that causes bus
off and replace

Still bus off?

No

Done

Yes

GET HELP

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 10

Start 2: DeviceNet Plant Floor Troubleshooting Flowchart(Intermittent Failures)

Do you have a
DeviceNetdiagnostic tool?

No

Yes

O

Connect tool to diagnose bus.
(Monitor voltages, CAN frame errors,etc.)

Problemdiagnosed?

No

Yes

Fix problem indicatedProblem fixed?

No

Yes

Go to
P

Done

See
Page 12

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 11

P

Does problem
occur with noise(from external
device or event)?

VFD load dumps, Servos
enabled, Welding, Other
Maintenance in the Area
(External to Network), etc.

No

Yes

Go to
R

Check noisy device’s grounding

See
Page 14Is the device’s
grounding correct?

Yes

No
Grounding problem

Fix grounding

Problem fixed?

No

Yes

Done

Go to
Q
See
Page 13

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 12Q

Is there a noisy
device on
DeviceNet?

Go to
R

Yes

See
Page 14

Replace DeviceNet interface card onthat device

Problem fixed?

e.g. VFD, Welding,
Robot, Motor etc.

No

No

Yes

Done

DeviceNet Plant Floor Troubleshooting Guide

Call Manufacturer

PUB00147R0

Page 13

R
Check DeviceNet grounds(missing grounds or ground loops).

Grounds OK?

Yes

No

Fix grounds.

Problem fixed?

No

Yes

Done

Go to
F
See
Page 5

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 14

Start 3: DeviceNet Plant Floor Troubleshooting Flowchart(Node Problem)
If this is your third time through this process, consider the possibility that this is a network issue rather than a node issue.

Turn Auxiliary and DeviceNet PowerOFF, Wait 10 seconds, Turn back ON.
Verify scanner is functioning.

Is the Device’s
Network Status LED
flashing or solid green?

Is the Device’s
Network Status
LED solid green?

Yes

No

Go to
V
See
Page 17

No

Yes

Unplug device and check DeviceNet
power and Auxiliary power at the node

Voltages OK?

Done

No

Find and fix voltage problem
Yes

Is the device’s
Network Status
LED on solid red?

No

Go to
Start 3
See
Above

Yes

Go to
S

Go to
V

See
Page 16

See
Page 17

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 15

S
Verify node address and data rate. If nochanges required, replace node. Be surethat node address, data rate and .EDS
revision are correct.

Is the device’s Net
Status LED on
solid red?

No

Go to
Start 3

Yes

See
Page 15

Unplug nodeConnect DeviceNet diagnostic tool

Can you see othernodes on the
network?

Possible cable, teeor other node thatis causing the
problemNo

Replace drop cable or tee
Yes

Disconnect DeviceNet diagnostic tool
reconnect node. Disconnect adjacentnodes. Turn Auxiliary and DeviceNet
Power OFF, Wait 10 seconds, Turnback ON.

Go toStart 3
See
Page 15Is the device’s
Network Status LED
on solid green?

No

Yes

Go to
T

Go to
U

See
Page 17

See
Page 17

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 16

TU

One of the adjacent nodes may becausing the problem. Replace badnode. Reconnect nodes one at a time
to confirm which node is causing the
problem.

Disconnect nodes until the device’s
Net Status LED is on solid green.

Reset power after removal of eachnode to determine if problem has
been corrected.

Go toStart 3
See
Page 15

Reconnect nodes one at a time toconfirm which node is causing the
problem.

Replace offending node.

If the node’s Net
Status LED is
flashing green, it isready to establish
communication.

V

Go to
Start 3
See
Page 15

Check HMI or scanner for diagnostic
information for corrective action.

Was corrective
action successful?

Yes

Done

No

Walk the network and checkconnections.

Go to
W
See Page 18

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 17

W

Problem found andfixed?

Yes

No

Replace node

Node online?

Yes

No

Replace drop cable or tee

Node online?

Yes

Done

No

Go to
U
See
Page 17

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 18

“Walking” the Network
Here are the things to keep in mind and look for when walking a network.
First try to look at a drawing or layout of the network so you know where the cables go and if thelengths are correct. Sometimes this is not possible but look around in the controller cabinet forthis information. Also remember that Auxiliary Power topology and implementation is just as
important as DeviceNet topology and implementation. Check both when walking the network (I.e.
for additional information, see Auxiliary Power – Section 14 in the DeviceNet Network Checklist).
•••

Loose connections are the number one cause of failures.
-

Make sure all connections are undamaged.

-

Connections may look good but not be tight. Check them.

Cable stress is the second thing to look for.
-

Cable radii might be too tight or stressed with tie wraps. There is a lot of vibration in aplant and if the cables are stressed it will create a failure point.

-

Some cable trays are mounted on long fence post and the cables brought down fromthem. At the point where they leave the cable tray and bend down could be a potential
spot for failure.

Grounds are very important!
- Visually inspect grounding to assure that grounding location is clean and connection istight. Make sure that all components are properly grounded.

•

Separate high voltage cables from DeviceNet cables!
-

Power, welding or servo cables are sometimes put on top of the DeviceNet cables or put
in the same cable trays. DeviceNet cables must have the proper distance between thesecables.

-To clean up the wiring power, servo, or welding cables are tie wrapped together.
DeviceNet cables must have the proper distance between these cables.

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 19

Segmenting a network to troubleshoot a problem.
Finding a network cable problem is sometimes not the easiest thing to detect. The following
step-by-step process will assist in locating cabling issues:•

Divide the network into two halves to determine which half is causing the trouble byphysically disconnecting the trunk cable and placing the terminating resistor at the break
point

•

Once you determine the half causing the trouble you can approach the problem two ways.
− Continue to divide the defective portion of the network in half to further isolate thetrouble; or− Re-walk the network making sure that all connections are still “OK” .If everything looks“OK” then start at the controller and go to the first drop. Break the trunk cable andinsert a terminator. Walk the terminator down the trunk until the network fails.

Once the problem location has been determined, consider the following cable connection /details as possible causes of the problem:−−−−

Tee Connection
Drop Connection
Node Connection
Loading problem with a node or insufficient bus power. (A volt-amp-meter should be
used to determine if the problem is related to bus loading).

If the network has been running and then fails, it is often due to a bad cable or “Tee” connection.

Remember: There could be one or more causes for a specific problem. Take your time andcheck thoroughly to minimize the possibility of missing something.

DeviceNet Plant Floor Troubleshooting Guide

PUB00147R0

Page 20

Cell Number :Tool Number :Percent Complete:Station Number :DeviceNet Network Checklist
The following items should be completed during the implementation of DeviceNet networks commissioning. This will act as a record of the values
attained after installation of a working network and can be used for comparison for any future network / device troubleshooting.

ID

Item Description

Checked

Date

Comments

Physical Inspection

1

Are all DeviceNet devices approved for use on the project?
Make sure that DeviceNet taps are of the proper type.

___/___/___

2

Are 24VDC Power Supply calculations supplied? If the
network uses more than one supply, is the network connected
as designed?

___/___/___

Are all the trunk and drop cables separated from high voltage
and potential noise sources in accordance with the ODVA
DeviceNet Planning and Installation Guide?

___/___/___

Are all DeviceNet Drop & Trunk line cables routed withoutstrain on the connection points due to bending or tension?
Are all connections tight?

___/___/___

3
4
5a

Are the drop cables less than or equal to 20 feet (6 meters)?

___/___/___

5b

Is the sum of all drop lines less than the maximum allowed forthe network data rate DeviceNet specification?

___/___/___

6a

Is the trunk line less than the maximum length allowed for the
network data rate in the DeviceNet specification?

___/___/___

6b

Are both terminating resistors in place at the ends of the trunkline?

___/___/___

7

Are all selectable DIP switch / rotary switch settings (nodeaddress & baud rate) correct?

___/___/___

8

Is the DeviceNet 24VDC power supply (V-) bonded directly to
the ground buss bar (#12 wire) at one location only?

___/___/___

9

Are there any frayed or exposed wires on open styleconnectors creating a possible shorted condition?

___/___/___

10

If the DeviceNet network uses more than one power supply,
are the V- connections of all power supplies tied together andV- only bonded to the ground buss at one location?

___/___/___

Note regarding all Electrical Tests that follow:
Always keep the same reference point when making measurements. This allows you to trace wiring problems and find grounding problems. If you put
the black lead on the Earth ground point, make sure you always use the same point and the same lead. When performing any resistance check, you
cannot have less than “0” Ohms. A negative resistance value indicates you may have voltage on the ground, or on the wire you are checking. Remove
the source of any voltage to get an accurate measurement.

Design Source ___________________________________

Controls Engineer______________________________

Design Engineer _________________________________

Date______________________________

DeviceNet Plant Floor Troubleshooting Guide – DeviceNet Check List

PUB00147R0

Page 21

Cell Number :Tool Number :ID

11Percent Complete:Station Number :Item Description

Checked

Date

Comments

Network Termination Test
1.
2.
3.
4.

Follow shutdown procedures (if any)
Stop all network communication.
Turn all network and auxiliary power supplies off.
Measure and record the DC resistance between CANH
and CANL at the middle and ends of the network.

If the measured value is <50 ohms
Check for short circuit between CANH and CANL
wiringCheck for more than two terminating resistors
Check nodes for faulty transceivers
If the measured value is 50-70 ohms
Normal (Do nothing)___/___/___

If the measured value is 71-125 ohms
Check for open circuits in CANH or CANL wiring
Check for one missing terminating resistor
If the measured value is > 125 ohms
Add terminating resistor
Check for open circuits in CANH and CANL wiring

Design Source ___________________________________

Controls Engineer______________________________

Design Engineer _________________________________

Date______________________________

DeviceNet Plant Floor Troubleshooting Guide – DeviceNet Check List

PUB00147R0

Page 22

Cell Number :Tool Number :ID

Percent Complete:Station Number :Item Description

12

Checked

Date

Comments

Network Power Supply Ground Test
1.

Turn all network power supplies off. Disconnect the Vand Shield wires from ground and from each other.

2.

Using a Digital Voltmeter, measure DC voltage fromshield to ground at all power supplies. Is there less1than 1VDC?

3.

Remove all sources of voltage before continuing.

4.

Measure and record the DC resistance between Vand earth ground.
Measured value should show infinite resistance. If
other value is measured, look for swapped V- andshield wires at termination points.

5.

Measure and record the DC resistance between Shieldand earth ground.
Measured values greater than 20kΩ are considered
Normal. For measured values that are greater than
1 kΩ and less than 20 kΩ:-

Disconnect both DeviceNet connectors on the topof the main control panel and repeat the above
procedure. If the problem remains, checkconnections in the main control panel. Look forswapped V- and shield wires at termination
points.

-If the problem went away, segment the network
and isolate the location of the problem, andcheck for grounded V- or Shield wires.
Sometimes the V- and Shield connections aretransposed, which would cause ground loops.

6.

Reconnect the V- and Shield wires to ground.

7.

Go to each end of the network and remove terminator.
Check resistance between V- and Shield to verify that
there is not a broken shield wire. DC Resistance1
should be < 20Ω.

___/___/___For measured values greater than 20Ω, check for
broken shield

1

Does not apply to applications in which flat cable is utilized for DeviceNet Communication.

Design Source ___________________________________

Controls Engineer______________________________

Design Engineer _________________________________

Date______________________________

DeviceNet Plant Floor Troubleshooting Guide – DeviceNet Check List

PUB00147R0

Page 23

Cell Number :Tool Number :ID

13Percent Complete:Station Number :Item Description

Checked

Date

Comments

Network Power Supply Common Mode Voltage Test
1.

Turn all network power supplies on.

2.

Configure all nodes for their maximum current draw
from network power. Turn on outputs that use network
power.

3.

Measure and record the DC voltage between V+ and
V- where each power supply connects to the trunk.

4.

Measure and record the DC voltage between V+ and
V- at the ends of the network.
Measured values between 11.0 VDC and 25.0 VDC
are consistent with the DeviceNet Specification forproper DeviceNet communication.
However, input devices that may rely V+ and V- forpower may not operate properly at voltages less than
20 VDC. Check input device (e.g. proximity sensors,
photoelectric sensors, etc.) to verify device is within
voltage specifications.

5.

Measure between V- and Shield. Measured values
less than 4.6 VDC are considered normal.

___/___/___

If measured value from:
Item 4. Is < 11.0 VDC; or
Item 5. Is > 4.6 VDC,
The network may not operate properly.
Possible solutions are :- Shorten the overall length of the network cable.
- Move the power supply in the direction of theoverloaded section.
- Move nodes from the overload section to less loaded
section.
- Move high current loads close to the power supply.
- Break the network into two separate networks.
- Add power supply.

Design Source ___________________________________

Controls Engineer______________________________

Design Engineer _________________________________

Date______________________________

DeviceNet Plant Floor Troubleshooting Guide – DeviceNet Check List

PUB00147R0

Page 24

Cell Number :Tool Number :ID

14Percent Complete:Station Number :Item Description

Checked

Date

Comments

Auxiliary Power Measurements
1.

Monitor the voltage present at both ends of theauxiliary power trunk cable under normal operating
conditions and record the high and low values
observed. The use of an oscilloscope may benecessary.

2.

Check all manufacturers’ specifications to verify thatthe auxiliary power observed falls within the
manufacturers’ specifications.

___/___/___

If problems are observed, consider the following- Add an additional power supply- Shorten auxiliary power trunk line cabling- Check for influence of noise- Assure that the grounding requirements outlinedin the manufacturers’ specifications have beenmet.

Design Source ___________________________________

Controls Engineer______________________________

Design Engineer _________________________________

Date______________________________

DeviceNet Plant Floor Troubleshooting Guide – DeviceNet Check List

PUB00147R0

Page 25