ESD CAN-PCI/200 User manual

CAN-PCI/200
PCI-CAN-Interface
Hardware Manual
to Product C.2021.xx
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 1 of 23
esd electronic system design gmbh
Vahrenwalder Str. 207 • 30165 Hannover • ermany
http://www.esd.eu
Phone: [phone] • Fax: [phone]
esd electronic system design gmbh
Vahrenwalder Str. 207 • 30165 Hannover • ermany
http://www.esd.eu
Phone: [phone] • Fax: [phone]

N O T E
The information in this document has been carefully checked and is believed to be entirely reliable.
esd makes no warranty of any kind with re ard to the material in this document, and assumes no
responsibility for any errors that may appear in this document. In particular descriptions and
technical data specified in this document may not be constituted to be uaranteed product features
in any le al sense.
esd reserves the ri ht to make chan es without notice to this, or any of its products, to improve
reliability, performance or desi n.
All ri hts to this documentation are reserved by esd. Distribution to third parties, and reproduction
of this document in any form, whole or in part, are subject to esd's written approval.
© 2012 esd electronic system desi n mbh, Hannover
esd electronic system desi n mbh
Vahrenwalder Str. 207
30165 Hannover
Germany
Phone: [phone]
Fax: [phone]
E-Mail: [email protected]
Internet: www.esd.eu
Trademark Notices
QNX® and Neutrino® are trademarks of QNX Software Systems Limited, and are re istered trademarks and/or used in
certain jurisdictions.
VxWorks® is a re istered trademark of Wind River Systems, Inc.
CANopen® and CiA® are re istered community trademarks of CAN in Automation e.V.
Linux® is the re istered trademark of Linus Torvalds in the United States and/or other countries.
Windows is a re istered trademark of Microsoft Corporation in the United States and other countries.
All other trademarks, product names, company names or company lo os used in this manual are reserved by their
respective owners.
Pa e 2 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200

Document file: I:\Texte\Doku\MANUALS\CAN\PCI\200\En lisch\CAN-PCI200_Hardware_en_11.odt
Date of print: 2012-07-20
Document t pe
number: DOC0800
Hardware version: CAN-PCI/200 Rev. 1.0
Document Histor
The chan es in the document listed below affect chan es in the hardware as well as chan es in
the description of the facts, only.
Revision Chapter Changes versus previous version Date
1.1 - Added new trademarks 2012-04-13
1.1 - New safety instructions 2012-03-01
1.1 1.2 New picture of the top layer 2012-03-01
1.1 2 Update chapter “Hardware Installation” 2012-03-01
1.1 5 Update chapter “Correctly Wirin Electrically Isolated CAN Networks” 2012-03-01
1.1 6 Added new chapter “CAN Troubleshootin Guide” 2012-03-01
1.1 8 Update chapter “Order Information” 2012-03-01
Technical details are subject to chan e without further notice.
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 3 of 23

Safet Instructions
!When workin with CAN-PCI/200 follow the instructions below and read the manual carefully to protect yourself from
injury and the CAN-PCI/200 from dama e.
!The device is a built-in component. It is essential to ensure that the device is mounted in a way that cannot lead to
endan erin or injury of persons or dama e to objects.
!The device has to be securely installed in the control cabinet before commissionin .
!Protect the CAN-PCI/200 from dust, moisture and steam.
!Protect the CAN-PCI/200 from shocks and vibrations.
!The CAN-PCI/200 may become warm durin normal use. Always allow adequate ventilation around the CAN-PCI/200
and use care when handlin .
!Do not operate the CAN-PCI/200 adjacent to heat sources and do not expose it to unnecessary thermal radiation.
Ensure an ambient temperature as specified in the technical data.
!Do not use dama ed or defective cables to connect the CAN-PCI/200 and follow the CAN wirin hints in chapter:
"Correctly Wirin Electrically Isolated CAN Networks".
!In case of dama es to the device, which mi ht affect safety, appropriate and immediate measures must be taken, that
exclude an endan erment of persons and objects.
!Current circuits which are connected to the device have to be sufficiently protected a ainst hazardous volta e (SELV
accordin to EN 60950-1).
!The CAN-PCI/200 may only be driven by power supply current circuits, that are contact protected.
A power supply, that provides a safety extra-low volta e (SELV or PELV) accordin to EN 60950-1, complies with this
conditions.
Attention !
Electrostatic discharges ma cause damage to electronic components.
To avoid this, please perform the steps described on pa e 8 before you touch the CAN-PCI/200,
in order to dischar e the static electricity from your body.
Qualified Personal
This documentation is directed exclusively towards personal qualified in control and automation en ineerin .
The installation and commissionin of the product may only be carried out by qualified personal, which is
authorized to put devices, systems and electric circuits into operation accordin to the applicable national
standards of safety en ineerin .
Conformit
The CAN-PCI/200 is an industrial product and meets the demands of the EU re ulations and EMC standards
printed in the conformity declaration at the end of this manual for the use in industrial environment.
Intended Use
The intended use of the CAN-PCI/200 is the operation as a PCI-CAN interface.
The uarantee iven by esd does not cover dama es which result from improper use, usa e not in
accordance with re ulations or disre ard of safety instructions and warnin s.
!The CAN-PCI/200 is intended for installation in PCI systems only.
!The operation of the CAN-PCI/200 in hazardous areas, or areas exposed to potentially explosive
materials is not permitted.
!The operation of the CAN-PCI/200 for medical purposes is prohibited.
Service Note
The CAN-PCI/200 does not contain any parts that require maintenance by the user. The CAN-PCI/200 does
not require any manual confi uration of the hardware.
Disposal
Devices which have become defective in the lon run have to be disposed in an appropriate way or have to
be returned to the manufacturer for proper disposal. Please, make a contribution to environmental protection.
Pa e 4 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200

Table of contents
1. Overview...................................................................................................................................... 6
1.1 Description of the Module......................................................................................................6
1.2 PCB View with Connectors....................................................................................................7
2. Hardware Installation....................................................................................................................8
3. Technical Data..............................................................................................................................9
3.1 General Technical Data..........................................................................................................9
3.2 PCI-Bus.................................................................................................................................9
3.3 CAN Interface......................................................................................................................10
3.4 Software Support.................................................................................................................10
4. Connector Assi nments..............................................................................................................11
4.1 CAN.....................................................................................................................................11
5. Correct Wirin of Electrically Isolated CAN Networks.................................................................12
5.1 Heavy Industrial Environment (Double Twisted Pair Cable).................................................12
5.1.1 General Rules.............................................................................................................12
5.1.2 Device Cablin ............................................................................................................13
5.1.3 Termination..................................................................................................................13
5.2 Li ht Industrial Environment (Sin le Twisted Pair Cable).....................................................14
5.2.1 General Rules.............................................................................................................14
5.2.2 Cablin ........................................................................................................................15
5.2.3 Termination..................................................................................................................15
5.3 Electrical Groundin .............................................................................................................16
5.4 Bus Len th...........................................................................................................................16
5.5 Examples for CAN Cables...................................................................................................17
5.5.1 Cable for Li ht Industrial Environment Applications (Two-Wire)..................................17
5.5.2 Cable for Heavy Industrial Environment Applications (Four-Wire)...............................17
6. CAN Troubleshootin Guide.......................................................................................................18
6.1 Termination..........................................................................................................................18
6.2 Electrical Groundin .............................................................................................................19
6.3 Short Circuit in CAN Wirin ..................................................................................................19
6.4 CAN_H/CAN_L-Volta e ......................................................................................................19
6.5 CAN Transceiver Resistance Test .......................................................................................20
7. Declaration of Conformity...........................................................................................................21
8. Order Information.......................................................................................................................22
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 5 of 23

Overview
1. Overview
1.1 Description of the Module
Figure 1: Block circuit dia ram of CAN-PCI/200
The CAN-PCI/200 is a PC board desi ned for the PCI bus. It is available with one or optional two
CAN interfaces.
The ISO 11898 compliant CAN interfaces allow a data transfer rate of 1 Mbit/s. Amon many other
features, the bit rate can be set by software. The CAN interface is electrically isolated from the
other potentials by optocouplers and DC/DC-converters.
Pa e 6 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200
+5 V=
+5 V=
+5 V=
+5 V=
C
A
N
B
U
S
CAN
CAN
IRQ A
Physical
CAN
Layer
C
A
N
B
U
S
electrical isolation
DC/DC
Converter
DSUB
CiA pinning
CAN Controller
SJA1000
PCI Bridge
PLX PCI 052
electrical isolation
DC/DC
Converter PCI Card Edge Connector
CAN Controller
SJA1000
Physical
CAN
Layer
DSUB
CiA pinning
2nd CAN Interface
only at
CAN-PCI/200-2

1.2 PCB View with Connectors
Figure 2: Top layer view of the module with 2x CAN
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 7 of 23

Hardware Installation
2. Hardware Installation
Read the safet instructions at the beginning of this document carefull ,
before ou start with the hardware installation!
Danger!
Electric shock risk. Never carry out work while power supply volta e is switched on!
Attention !
Electrostatic dischar es may cause dama e to electronic components. To avoid
this, please dischar e the static electricity from your body by touchin the metal
case of the PC before you touch the CAN-PCI/200.
Procedure:
1. Switch off your computer and all connected peripheral devices (monitor, printer, etc.). Switch
off the connected CAN devices.
2. Dischar e your body as described above.
3. Disconnect the power supply of the PC from the mains.
If the computer does not have a flexible mains cable, but is directly connected to mains,
disconnect the power supply via the safety fuse and make sure that the fuse cannot switch
on a ain unintentionally (i.e. with caution label).
Danger!
Never carry out work while power supply volta e is switched on!
4. Open the case.
5. Select an open PCI slot and remove the slot cover at the back of the PC. Unfasten the screw
which fixes the slot cover and retain it for fixin the module afterwards.
The CAN module can be inserted into every PCI slot.
6. Insert the CAN-PCI/200 board into the selected PCI slot. Carefully push the board down until
it snaps into place.
7. Attach the board.
Use the screw you removed from the slot cover in step 5.
8. Close the computer case a ain.
9. Connect the CAN cable. Please note the wirin hints in chapter 5.
The first CAN interface (CAN net 0) has to be connected via the lower DSUB connector (X1)
and the second CAN interface (CAN net 1) has to be connected via the upper DSUB
connector (X3).
10. Connect the computer to mains a ain (mains connector or safety fuse).
11. Switch on the computer and the peripheral devices.
12. End of hardware installation.
Continue with the software installation.
Pa e 8 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200

3. Technical Data
3.1 General Technical Data
Ambient temperature 0...50 °C
Humidity 90 %, non-condensin
Supply volta e
via PCI-bus,
Nominal volta e / current (typ., at 20 °C):
5 V ±5% 0.18 A (1x CAN)
0.24 A (2x CAN)
Connectors
X1 (DSUB9/male ) - CAN
X3 (DSUB9/male) - optional CAN-Net 0
X100 (Card Ed e) - PCI-Bus
Dimensions 106,68 mm x 119,91 mm (PCB only)
Wei ht 85 (1 x CAN)
100 (2 x CAN)
Table 1: General technical data of the module
3.2 PCI-Bus
Host-Bus PCI bus accordin to PCI Local Bus Specification 2.1
PCI bus width 32 bit
Controller PLX 9052
Interrupt Interrupt-si nal A
Slot position no restrictions for the slot position, PCI brid es are tolerated
Board dimensions compatible with all 'short' PCI-card slots
Connector PCI-card ed e connector
Table 2: PCI bus data
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 9 of 23

Technical Data
3.3 CAN Interface
Number of CAN
interfaces
1,
optional 2 CAN interfaces
CAN controller SJA1000
CAN protocol Basic CAN 2.0A ISO 11898-1
Physical Layer physical layer accordin to ISO 11898-2, transmission rate is
pro rammable from 10 kbit/s to 1 Mbit/s
Bus termination terminatin resistor has to be set externally
Electrical separation of
CAN interfaces from
other units and from
each other
separation by means of optocouplers and DC/DC-converters
DeviceNet-Option
adapter board with DeviceNet connector in Phoenix Combicon style,
optocouplers and CAN driver accordin to DeviceNet specification
'DeviceNet Communication Model and Protocol, Rel. 2.0'
Table 3: Data of the CAN interface
3.4 Software Support
Software drivers are available for Windows® and Linux®. Drivers for other operatin systems are
available as well. For detailed information about the driver availability of your special operatin
system, please see chapter '8. Order Information' at pa e 24 or contact our sales team:
[email protected].
Pa e 10 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200

4. Connector Assignments
4.1 CAN
The si nal assi nments of CAN-net 0 (X1) and of the optional CAN-net 1 (X3) are identical.
Device connector: 9-pin DSUB connector, male
Pin Position:
Pin Assignment:
Signal Pin Signal
1
reserved
(CAN_GND)
6
2
CAN_L
CAN_H
7
3
CAN_GND
reserved
8
4
reserved
reserved
9
5
reserved
Signal Description:
CAN_L, CAN_H ... CAN si nal lines
CAN_GND ... reference potential of the local CAN physical layer
(CAN_GND)... optional reference potential of the local CAN physical layer
reserved ... reserved for future applications, do not connect!
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 11 of 23
12345
6 7 8

Correct Wiring of Electricall Isolated CAN Networks
5. Correct Wiring of Electricall Isolated CAN Networks
For the CAN wirin all applicable rules and re ulations (EC, DIN), e. . re ardin electroma netic
compatibility, security distances, cable cross-section or material, have to be met.
5.1 Heav Industrial Environment (Double Twisted Pair Cable)
5.1.1 General Rules
Note:
esd only rants the compliance with directive 2004/108/EC, if the CAN wirin is carried
out with sin le shielded double twisted pair cables that match the requirements of ISO
118982-2 (table 9).
The followin general rules for the CAN wirin with sin le shielded double twisted pair cable must
be followed:
1A cable type with a wave impedance of about 120 Ω ±10% with an adequate wire cross-section
(0.22 mm²) has to be used. The volta e drop over the wire has to be considered!
2For heavy industrial environment use a four-wire CAN cable. Connect
•
•
•
two twisted wires to the data si nals (CAN_H, CAN_L) and
the other two twisted wires to the reference potential (CAN_GND) and
the cable shield to functional earth (FE) at least at one point!
3The reference potential CAN_GND has to be connected to the functional earth (FE) at exactly one
point.
4A CAN bus line must not branch (exception: short cable stubs) and has to be terminated with the
characteristic impedance of the line ( enerally 120 Ω ±10%) at both ends (between the si nals
CAN_L and CAN_H and not at GND)!
5Keep cable stubs as short as possible (l < 0.3 m)!
6Select a workin combination of bit rate and cable len th.
7Keep away CAN cables from disturbin sources. If this can not be avoided, double shielded cables
are recommended.
Figure. 3: CAN wirin for heavy industrial environment
Pa e 12 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200
CAN GND
CAN_L
CAN_H
CAN_GND
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
CAN_L
CAN_H CAN_GND
Shield
CAN_GND
twisted twisted
5
6
7
9
8
1
4
3
2
9
1
4
5
6
7
3
8
2
Single shielded
double twisted pair cable
(four wire cable,
2x 2x 0.22mm²)
wire shield
earth (FE)
Wire Layout
(Example)
Signal assignment of single shielded double twisted pair cable
with earth and termination
n.c. = not connected
DSUB9 connector
(female or male)
pin desi nation
connector case
DSUB9 connector
(female or male)
pin desi nation
CAN cable with connectors
connector case

5.1.2 Device Cabling
●To connect CAN devices which are equipped with one CAN connector per net, use
T-connectors and cable stubs (shorter than 0.3 m).
Attention:
If sin le shielded double twisted pair cables are used, realize the T-connections by
means of connectors that support connection of two CAN cables at one connector
where the cable’s shield is looped throu h e. . DSUB9 connector from ERNI
(ERBIC CAN BUS MAX, order no.:154039).
The usa e of esd’s T-connector type C.1311.03 is not recommended for sin le
shielded double twisted pair cables because the shield potential of the conductive
DSUB housin is not looped throu h this T-connector type.
Furthermore, mixed use of sin le twisted and double twisted cables should be
avoided!
Figure. 4: Example for proper wirin with sin le shielded double twisted pair cables
5.1.3 Termination
●Use external termination plu s, because they can later be rediscovered more easily than
internal terminations within the CAN devices!
●A 9-pin DSUB-connector with inte rated switchable termination resistor can be ordered e. .
from ERNI (ERBIC CAN BUS MAX, female contacts, order no.:154039).
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 13 of 23
CAN_L
CAN_GND
CAN_H
FE
esd
CAN Modul
Shield (Abschirmung)
esd
CAN Modul
esd
CAN Modul
CAN_GND connected
to functional earth (FE)
at exactly one point
Net 2
Net 1
e.g. CPCI/405,
PMC-CAN/331,
EPPC-405, etc.
CAN Board
termination
switched OFF
CAN T-Connector
(DSUB connector, female),
with switchable
termination
CAN
T-Connector
connected to earth (FE)
via computer housing
termination
switched OFF
CAN
T-Connector
CAN
T-Connector
termination
switched ON
termination
switched ON
Attention:
Watch for the correct position of the
termination switches at the connectors!
CAN
T-Connector

Correct Wiring of Electricall Isolated CAN Networks
5.2 Light Industrial Environment (Single Twisted Pair Cable)
5.2.1 General Rules
Note:
esd only rants the compliance with directive 2004/108/EC, if the CAN wirin is carried
out with sin le shielded double twisted pair cables that match the requirements of ISO
118982-2 (table 9).
The followin general rules for CAN wirin with sin le shielded single twisted pair cable must be
followed:
1A cable type with a wave impedance of about 120 Ω ±10% with an adequate wire cross-section
(0.22 mm²) has to be used. The volta e drop over the wire has to be considered!
2For li ht industrial environment use at least a two-wire CAN cable. Connect
•
•
the two twisted wires to the data si nals (CAN_H, CAN_L) and
the cable shield to the reference potential (CAN_GND)!
3The reference potential CAN_GND has to be connected to the functional earth (FE) at exactly one
point.
4A CAN net must not branch (exception: short cable stubs) and has to be terminated with the
characteristic impedance of the line ( enerally 120 Ω ±10%) at both ends (between the si nals
CAN_L and CAN_H and not at GND)!
5Keep cable stubs as short as possible (l < 0.3 m)!
6Select a workin combination of bit rate and cable len th.
7Keep away cables from disturbin sources. If this cannot be avoided, double shielded wires are
recommended.
Figure. 5: CAN wirin for li ht industrial environment
Pa e 14 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200
CAN GND
CAN_H
CAN_GND
n.c.
n.c.
n.c.
n.c.
CAN_L 1
4
5
6
7
9
2
3
8
9
1
4
5
6
7
3
8
2
earth (FE)
CAN_L
CAN_H
CAN_GND
Single shielded
twisted pair cable
(two wire cable,
1x 2x 0.22mm²)
CAN_GND
(at wire shield)
Wire Layout
Signal assignment of single shielded twisted pair cable
with earth and termination
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c.
n.c. = not connected
DSUB9 connector
(female or male)
pin desi nation
connector case connector case
DSUB9 connector
(female or male)
pin desi nation
CAN wire with connectors

5.2.2 Cabling
●for devices which have only one CAN connector per net use T-connector and stub (shorter
than 0.3 m) (available as accessory)
Figure. 6: Example for proper wirin with sin le shielded sin le twisted pair wires
5.2.3 Termination
●Use external termination plu s, because they can be rediscovered more easily than internal
terminations within the CAN devices!
●9-pin DSUB-termination connectors with male and female contacts and earth terminal are
available as accessories
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 15 of 23

Correct Wiring of Electricall Isolated CAN Networks
5.3 Electrical Grounding
●CAN_GND has to be connected between the CAN devices, because esd CAN devices are
electrically isolated from each other!
●CAN_GND has to be connected to the earth potential (FE) at exactl one point of the
network!
●Each CAN interface without electrically isolated interface acts as an earthin point. For this
reason do not connect more than one CAN device without electrically isolated CAN
interface!
●Earthin can e. . be made at a connector/T-connector.
5.4 Bus Length
●Optical couplers are delayin the CAN si nals. esd modules typically reach a wire len th of
37 m at 1 Mbit/s within a closed net without impedance disturbances like e. . cable stubs
>> 0.3 m.
Bit rate
[Kbits/s]
Typical values of reachable
wire len th with esd
interface lmax [m]
CiA recommendations
(07/95) for reachable wire
len ths lmin [m]
1000
800
666.6
500
333.3
250
166
125
100
66.6
50
33.3
20
12.5
10
37
59
80
130
180
270
420
570
710
1000
1400
2000
3600
5400
7300
25
50
-
100
-
250
-
500
650
-
1000
-
2500
-
5000
Table 4: Recommended cable len ths at typical bit rates (with esd-CAN interfaces)
Note:
Please note the recommendations accordin to ISO 11898 for the selection of the cross
section of the wire dependin of the wire len th.
Pa e 16 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200

5.5 Examples for CAN Cables
5.5.1 Cable for Light Industrial Environment Applications (Two-Wire)
Manufacturer Cable T pe
U.I. LAPP GmbH
Schulze-Delitzsch-Straße 25
70565 Stutt art
Germany
www.lappkabel.com
e. .
UNITRONIC ®-BUS CAN UL/CSA (1x 2x 0.22)
(UL/CSA approved) Part
No.: 2170260
UNITRONIC ®-BUS-FD P CAN UL/CSA (1x 2x 0.25)
(UL/CSA approved) Part
No.: 2170272
ConCab GmbH
Äußerer Eichwald
74535 Mainhardt
Germany
www.concab.de
e. .
BUS-PVC-C (1x 2x 0.22 mm²) Order No.: 93 022 016
(UL appr.)
BUS-Schleppflex-PUR-C (1x 2x 0.25 mm²) Order No.: 94 025 016 (UL appr.)
5.5.2 Cable for Heav Industrial Environment Applications (Four-Wire)
Manufacturer Cable T pe
U.I. LAPP GmbH
Schulze-Delitzsch-Straße 25
70565 Stutt art
Germany
www.lappkabel.com
e. .
UNITRONIC ®-BUS CAN UL/CSA (2x 2x 0.22)
(UL/CSA approved) Part
No.: 2170261
UNITRONIC ®-BUS-FD P CAN UL/CSA (2x 2x 0.25)
(UL/CSA approved) Part
No.: 2170273
ConCab GmbH
Äußerer Eichwald
74535 Mainhardt
Germany
www.concab.de
e. .
BUS-PVC-C (2x 2x 0.22 mm²) Order No.: 93 022 026
(UL appr.)
BUS-Schleppflex-PUR-C (2x 2x 0.25 mm²) Order No.: 94 025 026 (UL appr.)
Note:
Confi ured CAN cables can be ordered from esd.
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 17 of 23

CAN Troubleshooting Guide
6. CAN Troubleshooting Guide
The CAN Troubleshootin Guide is a uide to find and eliminate the most frequent hardware-error
causes in the wirin of CAN-networks.
Figure. 7: Simplified dia ram of a CAN network
6.1 Termination
The termination is used to match impedance of a node to the impedance of the transmission line
bein used. When impedance is mismatched, the transmitted si nal is not completely absorbed by
the load and a portion is reflected back into the transmission line. If the source, transmission line
and load impedance are equal these reflections are eliminated. This test measures the series
resistance of the CAN data pair conductors and the attached terminatin resistors.
To test it, please
1. Turn off all power supplies of the attached CAN nodes.
2. Measure the DC resistance between CAN_H and CAN_L at the ends of
the network (see fi ure above) and at the centre of the network (if the network cable
consists of more than one line section).
The measured value should be between 50 Ω and 70 Ω. The measured value should be nearly the
same at each point of the network.
If the value is below 50 Ω, please make sure that:
- there is no short circuit between CAN_H and CAN_L wirin
- there are not more than two terminatin resistors
- the nodes do not have faulty transceivers.
If the value is hi her than 70 Ω, please make sure that:
- there are no open circuits in CAN_H or CAN_L wirin
- your bus system has two terminatin resistors (one at each end) and that they are 120 Ω
each.
Pa e 18 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200
1
120

CAN_H
CAN_GND
CAN_L
CAN_L
CAN_H
CAN_GND
V
120 
23
1
V
1


6.2 Electrical Grounding
The CAN_GND of the CAN network has to be connected to the functional earth potential (FE) at
only one point. This test will indicate if the CAN_GND is rounded in several places.
To test it, please
1.
2.
3.
Disconnect the CAN_GND from the
earth potential (FE).
Measure the DC resistance
between CAN_GND and earth
potential (see fi ure on the ri ht).
Connect CAN_GND to earth potential.
Figure. 8: Simplified schematic dia ram of round test measurement
The resistance should be hi her than 1 MΩ. If it is lower, please search for additional roundin of
the CAN_GND wires.
6.3 Short Circuit in CAN Wiring
A CAN bus mi ht possibly still be able to transmit data if there is a short circuit between CAN_GND
and CAN_L, but the error rate will increase stron ly. Make sure that there is no short circuit
between CAN_GND and CAN_L!
6.4 CAN_H/CAN_L-Voltage
Each node contains a CAN transceiver that outputs differential si nals. When the network
communication is idle the CAN_H and CAN_L volta es are approximately 2.5 volts. Faulty
transceivers can cause the idle volta es to vary and disrupt network communication.
To test for faulty transceivers, please
1. Turn on all supplies.
2. Stop all network communication.
3. Measure the DC volta e between CAN_H and GND
(see fi ure above).
4. Measure the DC volta e between CAN_L and GND
(see fi ure above).
CAN-PCI/200 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 Pa e 19 of 23
2
3
>1M 
CAN_H
CAN_GND
CAN_L

functional earth
(FE)

CAN Troubleshooting Guide
Normally the volta e should be between 2.0 V and 4.0 V.
If it is lower than 2.0 V or hi her than 4.0 V, it is possible that one or more nodes have faulty
transceivers. For a volta e lower than 2.0 V please check CAN_H and CAN_L conductors for
continuity. For a volta e hi her than 4.0 V, please check for excessive volta e.
To find the node with a faulty transceiver please test the CAN transceiver resistance (see below).
6.5 CAN Transceiver Resistance Test
CAN transceivers have one circuit that controls CAN_H and another circuit that controls CAN_L.
Experience has shown that electrical dama e to one or both of the circuits may increase the
leaka e current in these circuits.
To measure the current leaka e throu h the CAN circuits, please use an resistance measurin
device and:
1. Switch off the node and disconnect it from the network
(see fi ure below).
2. Measure the DC resistance between CAN_H and CAN_GND
(see fi ure below).
3. Measure the DC resistance between CAN_L and CAN_GND
(see fi ure below).
The measured resistance has to be about 500 kΩ for each si nal. If it is much lower, the CAN
transceiver it is probably faulty.
Another si n for a faulty transceiver is a very hi h deviation between the two measured input
resistance (>> 200%).
Figure. 9: Measurin the internal resistance of CAN transceivers
Pa e 20 of 23 Hardware Manual • Doc. No.: C.2021.21 / Rev. 1.1 CAN-PCI/200
4
5
6
CAN_H
CAN_GND
CAN_L

5 6
4

4
Power
CAN
Transceiver
Disconnect
Power !
Disconnect
CAN !
CAN node