Ethernet POWERLINKHigh Availability
EPSG DS 302-A V1.1.1

EPSG Draft Standard 302-A

Ethernet POWERLINKPart A: High Availability

Version 1.1.1© B&R(B&R Industrial Automation GmbH)
2023

EPSG DS 302-A V1.1.1-2-

B&R Industrial Automation GmbH

POWERLINK-Office
B&R Straße 15142 Eggelsberg
Austria

powerlink.office@br-automation.com
www.br-automation.com/en/technologies/powerlink/

The EPSG Draft Standard 302-A “Ethernet Powerlink, Part A: High Availability” has been provided by
Ethernet POWERLINK Standardisation Group (hereinafter referred to as “EPSG”). As a consequenceof the EPSG being dissolved from March 31st, 2023, B&R Industrial Automation GmbH will – as theformal successor of EPSG regarding the rights and content – make the Ethernet Powerlink Part A:
High Availability available as open source on it’s own website subject to the conditions mentioned in
the disclaimer under clause Pre. 1 of this document. B&R Industrial Automation GmbH especiallydisclaims liability for any personal injury, property or other damage, of any nature whatsoever, whether
special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication,use of, or reliance upon this, or any other EPSG Standard document.

EPSG DS 302-A V1.1.1

Pre. 1-3-Disclaimer

Use of this EPSG Standard is wholly voluntary. The EPSG disclaims liability for any personal injury,
property or other damage, of any nature whatsoever, whether special, indirect, consequential, orcompensatory, directly or indirectly resulting from the publication, use of, or reliance upon this, or any
other EPSG Standard document.
The EPSG does not warrant or represent the accuracy or content of the material contained herein,and expressly disclaims any express or implied warranty, including any implied warranty ofmerchantability or fitness for a specific purpose, or that the use of the material contained herein is freefrom patent infringement. EPSG Standards documents are supplied “AS IS”.
The existence of an EPSG Standard does not imply that there are no other ways to produce, test,
measure, purchase, market, or provide other goods and services related to the scope of the EPSG
Standard. Furthermore, the viewpoint expressed at the time a standard is approved and issued issubject to change brought about through developments in the state of the art and comments received
from users of the standard. Users are cautioned to check to determine that they have the latest editionof any EPSG Standard.
In publishing and making this document available, the EPSG is not suggesting or rendering
professional or other services for, or on behalf of, any person or entity. Nor is the EPSG undertaking toperform any duty owed by any other person or entity to another. Any person utilizing this, and anyother EPSG Standards document, should rely upon the advice of a competent professional indetermining the exercise of reasonable care in any given circumstances.
Interpretations: Occasionally questions may arise regarding the meaning of portions of standards as
they relate to specific applications. When the need for interpretations is brought to the attention of the
EPSG, the group will initiate action to prepare appropriate responses. Since EPSG Standards
represent a consensus of concerned interests, it is important to ensure that any interpretation has also
received the concurrence of a balance of interests. For this reason, the EPSG and its members are
not able to provide an instant response to interpretation requests except in those cases where thematter has previously received formal consideration.
Comments for revision of EPSG Standards are welcome from any interested party, regardless ofmembership affiliation with the EPSG. Suggestions for changes in documents should be in the form ofa proposed change of text, together with appropriate supporting comments. Comments on standards
and requests for interpretations should be sent to the address given on the page before.

Pre. 1.1

Patent noticeAttention is called to the possibility that implementation of this standard may require use of subject
matter covered by patent rights. By publication of this standard, no position is taken with respect to theexistence or validity of any patent rights in connection therewith. B&R shall not be responsible for
identifying patents for which a license may be required by an EPSG standard or for conducting
inquiries into the legal validity or scope of those patents that are brought to its attention.

EPSG DS 302-A V1.1.1

Pre. 2-4-

History

Vers.
0.0.1
0.0.2

Date
Author / Company
2006-06-06 S. Potier
Alstom
2006-06-09 S. Potier
Alstom

0.1.0

ZHW

0.1.1

2006-07-12 H. Doran/
C. Glattfelder
S. KrausA. Lange
S. Potier
2006-08-10 S. Potier

0.1.2

2006-09-06 S. Potier

Alstom

0.1.3

2007-03-05 S. Potier

Alstom

1.0.0

2008-02-21 S. Kirchmayer B&R

1.0.1

2007-12-17 S. Potier

1.0.2

2008-04-18 S. Kirchmayer B&R

Ring Redundancy

1.0.3

2008-10-03 S. Kirchmayer B&R

1.0.4

2008-10-13 S. Kirchmayer B&R

1.0.5

2009-02-19 S. Kirchmayer B&R

Medium status bits managed in PollRequest
optional
DLL_MNRingRedundancy_REC:
1C40h
instead of 1C20h
Conference call from February 10th 2009

1.0.6

2011-02-17 S. Kirchmayer B&R

1.0.7

2011-11-29 S. Kirchmayer B&R

1.1.0

2013-03-29 S. Kirchmayer B&R

1.1.0a2021-09-22 S. Kirchmayer B&R

1.1.1

2023-05-23 S. Kirchmayer B&R

Ixxat
B&R
AlstomAlstomAlstomshort description
Creation
Updated after High Availability TWG in Essen
on June 08th 2006
The document has been reworked into a
specification style

The document has been updated after review
of version 0.1.0 on August 09th 2006.
The document has been updated after lastcomments from ZHW (AMNI message
definition added…)
The document has been updated after EPSGTWG review
Minor layout changes.
Version changes to DS 1.0.0
Medium status bits managed in PollRequest

Some rewording,
additional sub-indices in 1F89h conditional,
normative device description entries added.
State changes to Draft Standard Proposal
Changes from TWG meeting 10/2011
Renaming of “must” to “shall” whereappropriate
Minor layout changes.
Version changes to DS 1.1.0
Typos and other corrections
Office address updated© B&R due to dissolution of EPSGEPSG DS 302-A V1.1.1

Pre. 3Pre. 1Pre. 1.1
Pre. 2Pre. 3Pre. 4Pre. 5Pre. 6Pre. 1.2
Pre. 1.3
Pre. 7
1
2
2.1
2.2
2.2.1
2.2.2
3
3.1
3.2
3.3
3.3.1
3.3.2
3.4
3.4.1
3.4.2
3.4.3
3.4.4
3.4.5
3.5
3.5.1
3.5.2
3.5.3
3.5.4
3.5.5
3.5.6
3.6
3.7
3.8
4
4.1
4.2
4.3
4.3.1
4.3.2
4.3.3
App. 1-5-

Content
Disclaimer
Patent noticeHistory
Content
TablesFiguresDefinitions and Abbreviations
Definitions
Abbreviations
References
Introduction
Medium redundancy
Topology
Link Selector
Functional description
Medium status
Managing Node Redundancy
Principles
Managing Node addresses
Configuration Manager
Device Configuration Data
Distribution of Configuration DataManaging Node NMT
Common Initialisation NMT State Machine
RMN NMT State Machine
NMT RMS ACTIVE State
NMT_RMS_STANDBY State
Transitions
Election mechanism
Boot-up time
Switch-over time
ActiveManagingNodeIndication (AMNI) frame
Example with default values
Example with configured values
Example with large configured values
Switch-over required by the application
POWERLINK Cycle Timing
Flag in SoA frame
Ring Redundancy
Topology and Functional Description
Ring Redundancy Status
Additional Object Description
Object 1F82h: NMT_FeatureFlags_U32
Object 1C40h: DLL_MNRingRedundancy_REC
Object 043Bh: DLL_MNRingRedundancy_TYPE
Device Description Entries (normative)

3
3
4
5
6
7
8
8
8
9
10
11
11
11
12
12
16
16
17
18
19
20
23
23
25
26
27
29
29
30
30
31
32
33
34
35
35
37
38
38
39
40
40
40
41
42

EPSG DS 302-A V1.1.1

Pre. 4
Tab. 1
Tab. 2
Tab. 3
Tab. 4
Tab. 5
Tab. 6
Tab. 7
Tab. 8
Tab. 9Tab. 10
Tab. 11
Tab. 12
Tab. 13
Tab. 14
Tab. 15-6-

TablesPOWERLINK SoA frame structure
POWERLINK frame structure
POWERLINK message flow showing MAC and POWERLINK addresses
Standby State Transitions
AMNI frame structure
AMNI frame data fields
Assigned multicast address
Additional plain NMT state command
Addtional NMT Command ID
NMTCommandData structure of NMTGoToStandby
NMTCommand data fields of NMTGoToStandby
POWERLINK SoA frame structure
Additional flags in SoA
POWERLINK SoA frame structure
Ring Redundancy NMT_FeatureFlags_U32 additional bit interpretation

13
14
18
29
32
32
32
35
35
35
35
37
37
40
40

EPSG DS 302-A V1.1.1

Pre. 5
Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.
Fig. 7.
Fig. 8.
Fig. 9.
Fig. 10.
Fig. 11.
Fig. 12.
Fig. 13.
Fig. 14.
Fig. 15.
Fig. 16.
Fig. 17.
Fig. 18.
Fig. 19.
Fig. 20.
Fig. 21.
Fig. 22.
Fig. 23.
Fig. 24.

-7-

Figures
Redundant medium network topology
Link Selector functional block
Example of medium failure
Example of medium failure
MN redundancy
Flying "240" Node-Id on failure of Active MN
Multiple Configuration Managers
Redundant Managing Node Device Configuration File
Setup of the network configuration data
Download of configuration data
Example Configuration for RMN 241
Download of local configuration Data
Update of the network configuration data on RMN 242
Common Initialisation of NMT State Machine
NMT State Diagram of a RMN
Detail state NMT_RMS_ACTIVE_EPL_MODE
Detail state NMT_RMS_STANDBY_EPL_MODE
Example of switch-over with default priorities
Example of switch-over with configured priorities
Example of switch-over with configured large priorities
POWERLINK Network timing constraints
POWERLINK switch-over timing in isochronous phase
Redundant ring topology“Open” Ring

11
12
14
15
16
17
19
19
20
21
22
22
23
25
26
27
28
33
34
35
36
36
38
39

EPSG DS 302-A V1.1.1-8-Pre. 6

Definitions and Abbreviations

Pre. 6.1

Definitions

Active Managing Node (AMN)An Active Managing Node is a Redundant Managing Nodewhich is in Active state (managing the POWERLINK network).
At a given time there is only one Active Managing Node in the
POWERLINK network, other Redundant Managing Node being
Standby Managing Node.

Link Selector (LS)A Link Selector allows a node to be connected on two different
physical networks.

Redundant Managing Node (RMN)A Redundant Managing Node is a device that is able to takeover the management of an POWERLINK network if the Active
Managing Node fails. A Redundant Managing Node can either
be in active state (AMN) or in standby state (SMN).

Single Point of Failure

A hardware or software component whose loss results in theloss of service

Standby Managing Node (SMN)

A Standby Managing Node is a Redundant Managing Nodewhich is in Standby State. It behaves as a Controlled Node, but
can switch to Active state in case of Active Managing Nodefailure.

Pre. 6.2

Abbreviations

AMN

Active Managing Node

AMNI

Active Managing Node Indication

cDCF

concise Device Configuration File

CFM

Configuration Manager

CN

Controlled Node

DCF

Device Configuration File

EPL

Ethernet POWERLINKFLSFirst Link Status

LS

Link Selector

MN

Managing Node

RMN

Redundant Managing Node

SLS

Second Link Status

SMN

Standby Managing NodeEPSG DS 302-A V1.1.1

Pre. 7[1]-9-References

EPSG Draft Standard 301 (EPSG DS 301), Ethernet POWERLINK, Communication Profile
SpecificationEPSG DS 302-A V1.1.1

1

-10-

Introduction

With increased deployment of Industrial Ethernet, it is widely used in motion control, machinery andplant control systems. Industrial Ethernet may find its use in a large variety of applications, including
mission critical applications that are usually not tolerant to system failures and the resulting loss ofservice. In such applications, a high level of availability is essential. Besides, most of the industries
now give heed to the cost of loss of productivity induced by lack of availability of the system.
With POWERLINK High Availability, the availability of the system is ensured in the event of acomponent failure. Both the nodes and medium redundancy prevent having a single point of failure in
the system1.
•
The Managing Node redundancy ensures the POWERLINK cycle production continuance,
keeping synchronicity and very low jitter in case of Managing Node failure.
•The use of two media carrying the same information at the same time ensures to be robust to
any network component (cable, media convertor, hub…) failure.
With POWERLINK High Availability, the switch-over time (recovery time) of the system is in the rangeof the POWERLINK cycle time. That ensures a very fast restoring of normal operation without any
downtime for the system.
The POWERLINK High Availability specification is an add-on of the Ethernet POWERLINK
Communication Profile Specification. It has been written in a way to ensure the full compatibility withstandard Ethernet POWERLINK devices.

1 The occurrence of one failure (e.g. one cable broken in a chain) is compensated by the system and does not lead to a system

failure. If a second failure occurs, there is no guarantee that the system works correctly any more. However the system will berobust to one failure of media added to one Managing Node failure.

EPSG DS 302-A V1.1.1

-11-

2

Medium redundancy

2.1

Topology

The medium redundancy is achieved thanks to two different physical networks. Each node shall belinked to both physical networks via a Link Selector (this functional block is described in 2.2.1).
All combinations of line and star (or tree) topology are allowed. The line topology will require externalhubs or internal hubs with 4 ports.

Hub

Managing Node

Hub

Hub

Controlled Node

Hub

Controlled Node

First
Link

Controlled Node
SecondLink

Fig. 1.

Redundant medium network topology

As far as possible, the topology of both physical networks should be identical (same number of hubs,same cable length…). It will ensure that a frame will reach a node on both links at the same time.
Anyway, the difference of path delay between both links shall not exceed 5.2 µs (transmission time forthe smallest Ethernet frame at 100Mbit/s). Thus the first bits of a frame will be received on one link
before the last bits of the frame will be transmitted on the second link. It will ensure that each node will
be able to detect that a frame is present on both links or not.

2.2

Link Selector

In a redundant POWERLINK network, all nodes shall be connected to two different physical networks.
Both physical networks shall convey the same redundant information.
Each node has to transmit on both links and to select one link for reception. This function is done by
the Link Selector functional block.

EPSG DS 302-A V1.1.1-12-

Protected Link
(to the node)

Link Selector

Fig. 2.

Frame
selection

Frame
duplication

First
Link

SecondLink

Link Selector functional block

The Link Selector could be implemented within the POWERLINK node itself (Internal Link Selector), or
within an external device connected to each POWERLINK node (External Link Selector).

2.2.1

Functional description

For each frame received from the node (on the Protected Link), the Link Selector shall simultaneouslytransmit this frame on the First and on the Second Link.
For each frame received from the redundant network (on the First Link, or on the Second Link, or onboth), the Link Selector shall do a frame selection and transmit this frame to the node on the Protected
Link.
The selection mechanism could be as simple as selecting the first received frame. But more
information could be taken into account for the selection (percentage of frames received with a bad
CRC on each Link…). As the Link Selector should be designed in the way to minimize the path delay
and jitter increase, it should avoid having a store and forward mechanism.
Note: When sending a frame in response to another one, special attention has to be paid to the
maximum path delay (5.2 µs). Otherwise collisions may occure.

2.2.2

Medium status

The Link Selector shall provide information about medium status to the POWERLINK nodes, in order
to inform the application of a medium failure. The medium status information will be introduced inside
POWERLINK SoA frames, response frames (PollResponse, StatusResponse, IdentResponse) andrequest frame (PollRequest).
In order to allow the detection of a cable issue in both directions (TX and RX)2 for each node, and toeasily locate the medium failure, the Link Selector should set the medium status bits in the following
way:•
If the Link Selector is in front of (or inside) an AMN (SoC, SoA and PollRequest received fromthe protected port) :o
For each response frame that is received from the redundant links, the medium status
bits shall be set according to the medium state at reception of this response frame.

2 The failure of a medium in only one direction is transient (time for hardware to detect the loss of link), usually a medium failure

in one direction leads to a medium not available in both directions. This depends on PHY’s implementation.

EPSG DS 302-A V1.1.1

-13-

o

For each SoA frame that is received from the protected link, die cable redundancy (CR)flag shall be set.
If the Link Selector is in front of (or inside) a SMN or a CN (SoC, SoA and PollRequest received
from the redundant ports)o
For each response frame (PollResponse, StatusResponse, IdentResponse) that isreceived from the protected link (and so shall be sent to both redundant links), themedium status bits shall be set according to the medium state at reception of the request
frame (PollRequest, StatusRequest, IdentRequest) on the redundant links.
o
For each request frame (PollRequest) that is received from the redundant links, themedium status bits shall be set according to the medium state at reception of this request
frame.
A Link Selector shall never reset a status bit which has been set by another Link Selector.

••

The bit 1 of byte 9 shall be used in the following message to show that cable redundancy is present in
the network:•

SoA

A Link Selector shall include information inside SoA if it is placed in front (or inside) an AMN.
Bit 1 = Cable Redundancy (CR) (0 = No cable redundancy, 1 = Cable redundancy)
Note: The byte 9 of this POWERLINK frame is the 23th byte in the Ethernet frame (not including 8
bytes of preamble)
Bit Offset
Octet Offset

7

0

Res

6

5

3

Destination2source3

NMTStatus

4

res

res

5

res

res

res

res

res

1

0

xx/resxx/res

res

res

res

6

RequestedServiceID

7

RequestedServiceTarget

8

EPLVersion
res2

Message Type

1

9

res

res

10-45
Tab. 1

4

res

xx

xx

CR

xx

reserved
POWERLINK SoA frame structure

The bits 7 and 6 of byte 5 should be used in the following messages:•
PollRequest•
PollResponse•
StatusResponse (ASnd)•
IdentResponse (ASnd)
A Link Selector shall include medium status information inside PollResponse. It may include medium
status information inside the PollRequest, StatusResponse and IdentResponse frames.
Bit 7 = First Link Status (FLS)
Bit 6 = Second Link Status (SLS)(0 = Link OK, 1 = Link not OK).
(0 = Link OK, 1 = Link not OK)EPSG DS 302-A V1.1.1-14-

Note: The byte 5 of these POWERLINK frames is the 19th byte in the Ethernet frame (not including 8
bytes of preamble)
Bit Offset
Octet Offset

7

0

Res

6

5

4

3

1

0

xx

xx

xx

Message Type1

Destination2source

3

xxx

4

xx

xx

5

FLS

SLS

xx

xx

xx

PR

6-n
Tab. 2

2

RS
xxx

POWERLINK frame structure

Note: The following two examples are only transient cases, a medium failure in one direction usuallyleads to a medium failure in both directions after the hardware has established a loss of link condition.
•

Example 1:

In the following example, the Link Selector in CN2 has only received the request frame on the Second
Link. So the Link Selector inside the CN2 will indicate in the response messages (PollResponse,
StatusResponse,) that First Link is in failure. The Link Selector inside the CN2 will also provide themedium failure information to CN2, setting the FLS bit of the PollRequest frame coming from the MN.
The Link Selector inside the MN will see both links ok, as a matter of fact it will receive the response of
the CN1 and CN2 on both links. But as it will not reset the medium status bits, the application in the
MN is able to detect that there is a medium issue between CN2 and MN.
MN

MN

LS

CN 1

LS

Hub

Hub

CN 1

Cable break inTX
(MN to CN2)

CN 2

LS

Hub

Hub

CN 2

First
Link
SecondLink

Fig. 3.
•

Example of medium failure

Example 2:

In the following example, the Link Selector inside the CN2 will receive valid frames on both links andwill not set the medium status bits of the response messages (PollResponse, StatusResponse) andrequest messages (PollRequest).

EPSG DS 302-A V1.1.1-15-

The Link Selector inside the MN will not see valid frame from CN2 on the First Link, and so will set the
FLS bit on the response message. Then the application in the MN is able to detect that there is amedium issue between CN2 and MN.
MN

MN

LS

SecondLink

Fig. 4.

Example of medium failure

CN 1
CN 2

Hub
First
Link

LS

CN 2

Hub

Cable break in RX(CN2 to MN)

LS

Hub

Hub

CN 1

EPSG DS 302-A V1.1.1

-16-

3

Managing Node Redundancy

3.1

Principles

The redundancy of a Managing Node is achieved with several (at least two) Redundant Managing
Nodes (RMNs) being deployed in the network. The POWERLINK network is monitored from them, anddue to pre-defined specifications one of them can take over the role of a Managing Node (MN) in caseof the AMN fails.
A RMN has two states: active and standby. For this reason, a RMN in an active state is called an“Active Managing Node” (AMN). On the other hand a RMN in a standby state, a “Standby Managing
Node” (SMN). An AMN behaves like a MN, and a SMN normally like a CN. The only difference
between a SMN and a CN is the continuous monitoring of the network traffic. In case of failure of theAMN, a SMN shall be capable of taking over the duty of the failed AMN and to manage the
POWERLINK network.

Fig. 5.

HubControlled
Node

Hub

Redundant Managing
Node in Standby State
(SMN)

Hub

RedundantManaging Node in
Active State (AMN)

Controlled
Node

MN redundancy

Although it is possible to deploy several RMNs at the same time, only one of them can be a MN in an
active state, whereby all of the others are concurrently in a standby state.
During boot up, an election mechanism will ensure that the RMN with the highest priority will become
AMN. The same applies to a failure of the AMN – a specification of the priority of each individual RMN
determines the order in which the SMNs try to take over the duties of the MN. Refer to 3.5 for moredetails about the priorities and the election mechanism.
A very critical phase in the POWERLINK network is the takeover of the AMN function by the SMN.
During this time it shall be guaranteed that all of the CNs remain fully functional. During and after theswitching, they are not allowed to leave their OPERATIONAL state, and de-synchronize themselves.
This can be achieved with the use of an identical network configuration for all RMNs.
Another requirement is that when a RMN takes over the task of an AMN, this shall take place without
going through the boot-up procedure. Therefore, a RMN shall be capable of monitoring the
POWERLINK network during the standby phase (SMN), to gather information about the connected
CNs.
Also the synchronization of the “TIME producer” within the MN shall take place during the standby
phase, as during the switching to an AMN, the SoC time stamp shall be synchronized.

EPSG DS 302-A V1.1.1-17-Beside these special SMN functionalities, the communication between an AMN and a SMN is thesame as between an AMN and a CN.
In order to remain compliant to the POWERLINK specifications, the AMN shall behave exactly as a
MN, communicating asynchronously and isochronously with the network.
The Controlled Nodes have to be configured in a way that they tolerate the loss of at least one cycle.
As a matter of fact, the detection of the AMN failure leads to have a missing SoC or SoA on the
network.
Inside a high available POWERLINK network only RMNs shall be used. The use of a standard MN(that does not have high availability features inside) in combination with RMNs is not allowed inside
the same POWERLINK network.
It is recommended that a RMN is an optional node.

3.2

Managing Node addresses

As all other POWERLINK nodes, each RMN is addressed by a unique POWERLINK node-ID. Two
ranges of POWERLINK node-IDs can be used for a RMN:•
[1..239]•[241..250]
The range [241...250] should be used by default if the configuration tool does not manage the RMNpriorities. As a matter of fact the Node-Id is used by default as priority differentiator. Refer to 3.5 fordetails about RMN priorities.
In order that the redundancy design of the “flying Managing Node” works, the AMN shall use the“flying” Node-Id 240 in addition to its own Node-Id. Above all, the regulation in the POWERLINK
specifications (refer to [1]) are met, that only one MN with Node-Id 240 is allowed to be present in the
network at a time.
The active/standby mechanism of the RMNs remains hidden to standard nodes. Only one active MN isseen in the network at a given time – always with the Node-Id 240. Thus the networking devices do
not see whether this is a standard MN or an AMN.

RedundantManaging Node(Active State ) NodeID = 241 & 240

RedundantManaging Node
(Standby State)
Node ID = 242

RedundantManaging Node
(In Failure)
Node ID = 241

RedundantManaging Node(Active State) NodeID = 242 & 240

Failureof MN
241

Controlled Node
Node ID = 1

Fig. 6.

Controlled Node
Node ID = 1

Flying "240" Node-Id on failure of Active MN

An AMN will use the “flying” Node-Id 240 as POWERLINK source address for messages related to the
management of the POWERLINK cycle (SoC, SoA, PollRequest…). But it will use its own Node-Id(241 for example) as POWERLINK source address for PollResponse.
As it will not produce the POWERLINK cycle, a SMN will only use its own Node-Id (241 for example)
as POWERLINK source address for all sent messages.

EPSG DS 302-A V1.1.1-18-

After a switch-over the AMN should send an NMTFlushArpEntry NMT command to all the nodes inorder to flush all ARP tables. As a matter of fact, the MAC address of the Node-Id 240 (IP address
192.168.100.240) will be changed after the switch-over. However it is not recommended to use the“flying” 240 address in IP communication, the own Node-Id of the RMN should be preferred.
An AMN should answer to requests addressed to both NodeId 240 and its own NodeId (241 forexample).
The following table shows the MAC and POWERLINK addresses of the messages flow before andafter the switch-over described in Fig. 6.
MAC Source

MAC Destination

Message TypePOWERLINK src

POWERLINK dest

MAC-MN1

01:11:1E:00:00:01

SoC

240

255

MAC-MN1

MAC-CN1

PollRequest

240

1

MAC-CN1

01:11:1E:00:00:02

PollResponse

1255

MAC-MN1

MAC-MN2

PollRequest

240

242

PollResponse

2423

255
255

MAC-MN2

01:11:1E:00:00:02

MAC-MN1

01:11:1E:00:00:02

PollResponse

2413

MAC-MN1

01:11:1E:00:00:03

SoA

240

255

Switch-over, MN2 becomes active
MAC-MN2

01:11:1E:00:00:01

SoC

2404

255

MAC-MN2

MAC-CN1

PollRequest

240

1

MAC-CN1

01:11:1E:00:00:02

PollResponse

1255

MAC-MN2

MAC-MN1

PollRequest

240

241

PollResponse

2413

255
255
255

MAC-MN1

01:11:1E:00:00:02

MAC-MN2

01:11:1E:00:00:02

PollResponse

2423

MAC-MN2

01:11:1E:00:00:03

SoA

240

Tab. 3POWERLINK message flow showing MAC and POWERLINK addresses

3.3

Configuration Manager

The Configuration Manager (CFM) functionality is an optional feature of the RMN that shall be
indicated by the device description entry D_CFM_ConfigManager_BOOL. The CFM is responsible forthe correct configuration of all devices belonging to a network. There is only one active CFM in the
network at a time while there can be several other inactive CFMs present on the Standby Managing
Nodes.
Redundant Managing
Node in Active State
CFM inActive state

Redundant Managing
Node in Standby State
CFM inStandby state

Redundant Managing
Node in Standby State
CFM inStandby state

3 The switch-over does not modify the list of Poll Response from RMNs, but the order of sending will be changed because theAMN will send its Poll Response at the end without sending any Poll Request.
4 After the switch-over the SoC is sent by the RMN2, but still with the “flying” POWERLINK node-ID 240.

EPSG DS 302-A V1.1.1

Fig. 7.

-19-

Multiple Configuration Managers

It is possible to have only one RMN with CFM functionality but several RMNs without this function in
the network. In this case, the switchover to a RMN without CFM is only possible after the network was
successfully configured once. Configuration consistency is no more guaranteed if a RMN without CFM
is running the network. Therefore it is recommended that all RMNs of a network have the CFM
functionality.
The priority-based master election algorithm determines the AMN during boot up of the network. It
shall be ensured, that the RMN with the CFM feature enabled (device description entry
D_CFM_ConfigManager_BOOL) are preferably used.

3.3.1

Device Configuration Data

The CFM of the RMN uses the object dictionary entries specified in the Ethernet POWERLINK
Communication Profile Specification. There is no need for further or different objects on the RMN. The
device configuration data itself contain all data to allow a CFM the complete network configuration.
For the network consistency it is important, that all CFMs within a segment have the same network
configuration data. In case of a switch over of RMNs, the new AMN will then be able to configure allnodes of the network. To keep the entire network configuration process as simple as possible for theapplication, the distribution of the device configuration data is performed automatically by the active
CFM as described in section 3.3.2. This mechanism also ensures the configuration consistency
among the CFMs.
The device configuration data are normally provided by a configuration tool and should contain all
configuration data to set up a device. For the configuration of the RMNs with CFM functionality, theconfiguration tool also has to provide the configuration data needed to configure the networking
nodes. This network configuration data are part of the RMN device configuration and are locally stored
on the RMN either as DCF (CFM_StoreDcfList_ADOM) or cDCF file (CFM_ConciseDcfList_ADOM).
Device Configuration File
(DCF or cDCF)
Local
Configuration Data

Network
Configuration Data
CFM_StoreDcfList_ADOM
CFM_ConciseDcfList_ADOM

Fig. 8.

Redundant Managing Node Device Configuration FileIt should be possible for any active CFM in the network to completely configure all the othernetworking nodes, especially the standby CFMs. To do so, the network configuration data inside thedevice configuration file should contain all the local configuration data of the CFMs including himself.

EPSG DS 302-A V1.1.1-20-

Device Configuration File
(DCF or cDCF)

Network
Configuration Data
CN 1 Local Config. Data
CN 2 Local Config. Data...
CN n Local Config. Data...
RMN 1 Local Config. Data
Own Local Config. Data
RMN n Local Config. Data

Fig. 9.

Identical

Local
Configuration Data

Setup of the network configuration data

The local configuration data of the RMNs contain data that may be set up individually to the location of
the RMN in the network. An example for such parameters is the individual PRes timeouts configuredin the RMN object NMT_MNCNPResTimeout_AU32. These values depend on the number of hub
levels and the line length between the RMN and the CNs.
While the local configuration data may be individual to all RMNs, the network configuration data are
identical to all.

3.3.2

Distribution of Configuration Data

To ease up the network configuration for the user, a mechanism shall be provided by the active CFM
that manages the automatic update of all standby CFMs. Based on this mechanism, the user only has
to update the configuration of the first AMN. During boot up, the active CFM distributes all relevant
data to the standby CFMs of the network.
The distribution process of the configuration data is split up into two parts:•
Download of the local configuration data stored in the DCF or cDCF file for a certain node•
Download of network configuration data from the active CFM to the standby CFMs
The download of the local configuration data stored in CFM_StoreDcfList_ADOM or
CFM_ConciseDcfList_ADOM is handled by the CFM processes defined in the Ethernet POWERLINK
Communication Profile Specification. The network configuration data is not part of the local
configuration data that is sent to the standby CFM during the standard update process. The network
data were excluded from there to avoid the recursion of configuration data within the RMN device
configuration files and to decrease the DCF and cDCF file sizes.
Distribution of the network information from the active CFM to the standby CFMs is done in a separate
process. The active CFM can easily determine which RMN needs to be updated with the network
configuration by evaluating NMT_FeatureFlags_U32.Bit8 of a node. During boot up this value istransferred within the IdentResponse of each node.

EPSG DS 302-A V1.1.1-21-

CFM_Update[Node ID]
Download local
configuration
data
NMT_FeatureFlags_U32[Nod ID].Bit8
Configuration Manager
DeactivatedConfiguration Manager
Activated
CFM_StoreDcfList_ADOM or
CFM_ConciseDcfList_ADOM
Download network
configuration
data

CFM_Update[Node ID]
E_OK

Fig. 10.

3.3.2.1

Download of configuration data

Configuration Example

There are three RMNs in the network (Node-Id 241 to 243) and one “normal” CN (Node-Id 1). RMN
241 and 242 both have the CFM feature enabled. RMN 243 has no CFM functionality. The
configuration tool provides a device configuration file (in concise DCF format) for the RMN 241 only.
This device configuration file is locally downloaded to the object dictionary of the RMN 241.

EPSG DS 302-A V1.1.1

-22-

Local
Configuration Data
Network Configuration Data
CFM_ConciseDcfList_ADOM

Identical

Device Configuration File
cDCF for Node ID 241

ID 1 Local Config. Data
ID 241 Local Config. Data
ID 242 Local Config. Data
ID 243 Local Config. Data

Fig. 11.

Example Configuration for RMN 241

At network boot up the RMN 241 becomes the AMN and starts to update the local configuration dataof all nodes in the network (see Fig. 12).
Node241
Object Dictionary
Local
Configuration Data
Network Configuration Data
CFM_ConciseDcfList_DOM

ID 1 Local Config. Data.
ID 241 Local Config. Data
ID 242 Local Config. Data
ID 243 Local Config. Data

Node242
Object Dictionary
Local
Configuration Data

Node243

Node1
Object Dictionary
Local
Configuration Data

Fig. 12.

Object Dictionary
Local
Configuration Data

Download of local configuration Data

After the Download of the local configuration data via the standard CFM functionality, the distribution
process for the network configuration data takes place. The RMN 241 downloads the content of object
CFM_ConciseDcfList_ADOM to the RMN 242 object CFM_ConciseDcfList_ADOM (see Fig. 13). This
download is required, as the node 242 indicated the support of the CFM feature via
NMT_FeatureFlags_U32.Bit8.

EPSG DS 302-A V1.1.1-23-

Node 241
Object Dictionary
Local
Configuration Data
Network Configuration Data
CFM_ConciseDcfList _ADOM

ID 1

Local Config. Data

ID 241 Local Config. Data
ID 242 Local Config. Data
ID 243 Local Config. Data.

Node 242
Object Dictionary
Local
Configuration Data
Network Configuration Data
CFM_ConciseDcfList _ADOM

ID 1 Local Config. Data
ID 241 Local Config. Data
ID 242 Local Config. Data
ID 243 Local Config. Data.

Node 1

Node 243

Object Dictionary

Object Dictionary

Local
Configuration Data

Fig. 13.

Local
Configuration Data

Update of the network configuration data on RMN 242

Now the RMN 242 has exactly the same network configuration data as the currently active CFM. Uponswitch over to RMN 242, the network configuration can be completely restored on every node, evenon the RMN 241 if necessary.
RMN 243 is obviously not capable to do the network configuration as it did not receive the network
configuration data from the RMN 241 during boot up. All this node can do when becoming the AMN isto keep the communication with the currently configured nodes alive.

3.4

Managing Node NMT

3.4.1

Common Initialisation NMT State Machine

The initialisation of the NMT state machine is common to MN, CN and RMN.
The NMT_StartUp_U32 object (index 1F80h), used to configure the boot up behaviour, will indicate if
the node can start as a RMN (bit 14). If the node can start as a RMN, it will enter in NMT_RMS state
to start as an Active MN or as a Standby MN.

EPSG DS 302-A V1.1.1

•
Octet

1

-24-

NMT_StartUp_U32 Value Interpretation
Bit

Value

Description0

The Node-Id shall be used for the boot-up procedure to determine if thenode shall start as MN or CN.
The Node-Id is used while leaving NMT_GS_INITIALISATION to decide
if the node should enter in NMT_CS or NMT_MS state machine.

1

The Node-Id shall not be taken into account for boot-up procedure. The
node shall start as RMN whatever the value of its Node-Id.
The state NMT_RMS will be automatically entered while leaving thestate NMT_GS_INITIALISATION.

14

A RMN should reset the bit 14 of NMT_StartUp_U32 upon reception of NMT_RestoreDefParam_REC.
This bit should be set only after a successful configuration of the RMN. That will prevent a
misconfigured (or not fully configured) RMN from becoming AMN.
If the bit is not set the RMN will not enter the NMT RMN State Machine but the NMT CN State
Machine (see Fig. 14).
A new NMT_RMS state machine is introduced. For details see 3.4.2.

EPSG DS 302-A V1.1.1-25-(NMT_GT1)
PowerOn(NMT_GT2)Reset

NMT_RMS_EPL_MODE

NMT_GS_INITIALISATION(NMT_GT4 …
NMT_GT7)(NMT_CT1)
Auto[(Node Id = 1..239 or
241..250) and (bit 14
of 1F80h is not set)](NMT_MT1)
Auto[NodeID = 240 and
bit 14 of 1F80h is not
set](NMT_RMT1)
Auto[bit 14 of 1F80h is set]

NMT_GS_COMMUNICATING

NMT_CSNMT CN State Machine

NMT_MSNMT MN State Machine

NMT_RMSNMT RMN State Machine(NMT_GT3)
PowerOffFig. 14.

Common Initialisation of NMT State Machine

Note: A node with Node-Id from 241 to 250 shall be capable to be RMN.

3.4.2

RMN NMT State Machine

The RMN NMT state machine should be regarded to be hosted by common initialisation NMT statemachine. In the state NMT_RMS_NOT_ACTIVE, the RMN will monitor the bus activity. If no activity isdetected, the RMN will enter in the state NMT_RMS_ACTIVE_EPL_MODE. If SoC or SoA are
detected on the bus, the RMN will enter in NMT_RMS_STANDBY_EPL_MODE.

EPSG DS 302-A V1.1.1-26-

NMT_GS_INITIALISATION

NMT_RMSNMT RMN State Machine(NMT_RMT1)
Auto[bit 14 of 1F80h is TRUE]

NMT_RMS_NOT_ACTIVE(NMT_RMT2)
Timeout (SoC, SoA)(NMT_RMT3)
Reception of SoC, SoA(NMT_RMT4)
Timeout (SoC, SoA)NMT_RMS_
ACTIVE_EPL_MODE(NMT_RMT5)
Reception of SoC, SoA,AMNI

NMT_RMS_STANDBY_EPL_MODE(NMT_RMT6)
Timeout (SoC)(NMT_RMT7)
Reception of SoC, SoA,
AMNI

Fig. 15.

3.4.3

NMT State Diagram of a RMN

NMT RMS ACTIVE StateThe RMN NMT state machine should be regarded to be hosted by common initialisation NMT statemachine.
The NMT_RMS_ACTIVE_EPL_MODE has the same functionality than the NMT_MS_EPL_MODE
specified in Ethernet POWERLINK Communicatin Profile Specification (check identity, state,configuration and communication of configured CN). Addtionionally it shall manage the transitions
between the active and standby states.
There are two ways to switch from the active to the standby state:•
Upon detection of another RMN communicating on the bus.
•
On reception of the new NMTGoToStandbyState command, in order to force the switch-over.
A RMN in NMT_RMS_ACTIVE_EPL_MODE state is called an AMN, it is in charge of managing the
POWERLINK network and shall produce the POWERLINK cycle.

EPSG DS 302-A V1.1.1

-27-

NMT_
RMT2

NMT_ RMS_ACTIVE_EPL_MODE

NMT_MS_
PRE_OPERATIONAL_1(NMT_MT6)
Error

NMT_
RMT4

(NMT_MT3)
Auto
NMT_MS_
PRE_OPERATIONAL_2

NMT_
RMT5
(NMT_MT4)
Auto
NMT_MS_READY_TO_OPERATE(NMT_MT5)
Auto

NMT_
RMT6

NMT_MS_OPERATIONAL

NMT_
RMT7

Fig. 16.

Detail state NMT_RMS_ACTIVE_EPL_MODE

Recommendation for the transition NMT_MT6: The error threshold for collisions may depend on thepriority of the RMN in order to ensure that the highest priority RMN remains in
NMT_MS_OPERATIONAL
state
while
a
lower
priority
RMN
goes
back
to
NMT_MS_PRE_OPERATIONAL_1 state.

3.4.4

NMT_RMS_STANDBY StateThe RMN NMT state machine should be regarded to be hosted by common initialisation NMT statemachine.
In NMT_RMS_STANDBY_EPL_MODE, the RMN behaves as a CN up to NMT_CS_OPERATIONAL
state. After that it has to prepare itself to be ready to switch-over to NMT_RMS_ACTIVE_EPL_MODE
in case of current AMN failure. The SMN monitors the network to detect the loss of the AMN (no more
SoC or SoA received).
In NMT_CS_OPERATIONAL state, the SMN will get information from the other nodes by listening to
the PollResponse/StatusResponse/IdentResponse. As a matter of fact, the SMN needs to know thelist of CNs that shall be polled after switchover.
The SMN shall get multiplexing information from SoC message, as the multiplexing shall be kept afterswitch-over.
In
state
NMT_CS_PRE_OPERATIONAL_2
the
SoC
will
be
monitored
with
NMT_BootTime_REC.MnWaitNoAct_U32 timer. Upon expiry of this timer, the RMN will enter
NMT_CS_PRE_OPERATIONAL_1 state (error condition, NMT_CT11).

EPSG DS 302-A V1.1.1

-28-

NMT_
RMT3

NMT_RMS_STANDBY_EPL_MODE

NMT_
RMT5

Reception of SoC,
SoA, AMNINMT_CS_
PRE_OPERATIONAL_1

Timeout (SoC, SoA)(NMT_CT4)
SoC
NMT_
RMT4
Timeout (SoC)

NMT_CS_
PRE_OPERATIONAL_2(NMT_CT6)
Auto
NMT_CS_READY_TO_OPERATE

No

NMT_
RMT6

Yes

?

(NMT_CT7)
NMTStartNode
Timeout (SoC)

At least one complete multiplex
Cycle received
NMT_
RMT7

(NMT_CT9)

NMT_CS_OPERATIONAL(NMT_CT8)
NMTStopNode

Reception of SoC,
SoA, AMNI(NMT_CT10)

NMT_CS_STOPPED(NMT_CT11)

Fig. 17.

Detail state NMT_RMS_STANDBY_EPL_MODEEPSG DS 302-A V1.1.1-29-

Transitions

3.4.5
NMT_RMT1

Auto [configuration setup completed, Configuration flag is TRUE / startobserving network traffic to decide whether to boot as AMN or SMN
If NMT_GS_INITIALISATION sub-state NMT_GS_RESET_CONFIGURATION
is completed and configuration flag is TRUE, state NMT_RMS_NOT_ACTIVE
shall be entered autonomously, e.g. the NMT RMN state machine shall beentered.

NMT_RMT2

Timeout SoC, SoA
No SoC or SoA message is received within the time defined by
NMT_BootTime_REC.MnWaitNoAct_U32 (see 3.5.1). No AMN is present in the
network.
Boot
as
an
AMN
i.e.
NMT_RMS_NOT_ACTIVE
to
NMT_RMS_ACTIVE_EPL_MODE

NMT_RMT3

Reception of SoC, SoA
Reception
of
SoC
or
SoA
withinthetimedefinedby
NMT_BootTime_REC.MnWaitNoAct_U32 (see 3.5.1). Start as a SMN i.e.
NMT_RMS_NOT_ACTIVE to NMT_STANDBY_EPL_MODE.

NMT_RMT4

Timeout (SoC, SoA(1))
No SoC or SoA message is received within the time defined by
Treduced_switch_over_MN resp. Tswitch_over_MN.(see 3.5.2) No AMN is present in the
network. The RMN NMT state machine is not in NMT_CS_OPERATIONAL
state or the multiplex cycle has not been fully received yet, so go to
NMT_MS_PRE_OPERATIONAL_1.
(1) SoA are only monitored in NMT_CS_PRE_OPERATIONAL_1

NMT_RMT5

Reception of SoC, SoA or AMNI.
Reception of SoC, SoA or AMNI within the time defined by Treduced_switch_over_MN
resp. Tswitch_over_MN (see 3.5.2), go to standby mode and stop sending messages
immediately. The MN state machine is not in NMT_MS_OPERATIONAL so startfrom NMT_CS_PRE_OPERATIONAL_1.
Application can also trigger this transition on the local node.

NMT_RMT6

Timeout (SoC)
No SoC message is received within the time defined by Tswitch_over_MN. No AMN
is present in the network. The RMS_STANDBY state machine is in
NMT_CS_OPERATIONAL state, so go to NMT_MS_OPERATIONAL

NMT_RMT7

Reception of SoC, SoA or AMNI
Reception of SoC, SoA or AMNI within the time defined by Tswitch_over_MN, go tostandby mode and stop sending messages immediately. The RMS_ACTIVE
statemachineisin
NMT_MS_OPERATIONAL
sogoto
NMT_CS_OPERATIONAL.
Application can also trigger this transition on the local node.

Tab. 4

3.5

Standby State Transitions

Election mechanism

Only one RMN is allowed to become an AMN, assuming the presence of more than one RMN, which
requires a suitable election mechanism.
The election mechanism is based on priorities assigned to each RMN. Each RMN shall have a uniquepriority, thus the election mechanism will ensure that the RMN having the highest priority will become
AMN in case of failure of the current AMN.
There are two options to ensure that each RMN has a different priority:

EPSG DS 302-A V1.1.1

•
•

-30-

The configuration tool provides the priority information to each RMN via the Object
NMT_BootTime_REC.MNSwitchOverPriority_U32 (index 1F89h, subindex 0Ah)
A default priority, based on the unique Node-Id, is given to each RMN. In that case each RMNshall have a unique Node-Id in the range [241...250].

The option 1 should be the preferred option. The option 2, also called the default option, should be
used only in case the configuration tool is not able to define priorities for RMNs.

3.5.1

Boot-up time

During the MN boot process the network is monitored by the MN for a period of time, given by theobject NMT_BootTime_REC.MnWaitNoAct_U32 (index 1F89h, sub index 01h) to determine whether
there is another MN active on the bus. A suitable configuration tool will initialise this object in each MN
across the network to achieve a de facto priority for a managing node to boot the network.

3.5.2

Switch-over time

In the states where the AMN produces a reduced cycle each SMN will start the timer(Treduced_switch_over_MN) on SoA reception. If this timer expires, the SMN with the highest priority will
broadcast an ActiveManagingNodeIndication (AMNI) message (see 3.5.3) and will switch to become
an AMN. Then it will start producing POWERLINK reduced cycles beginning with the next scheduled
cycle.

Treduced_ switch _ over_ MN = MNWaitNotAct_U32
In states where the MN produces SoC’s the SMN will implement a timer (Tswitch_over_MN) to be retriggered on reception of a SoC. Should the timer expire, the SMN with the highest priority shallbroadcast an AMNI message (see 3.5.3) and shall switch to become an AMN. Then it will start
producing SoC’s beginning with the next scheduled cycle.
The POWERLINK cycle is divided in MNSwitchOverCycledivider_U32 slices, the difference ofTswitch_over_MN between two nodes will be at least one slice.
The timer value will be computed by each SMN on the following way:

Tswitch _ over_ MN = Tcycle_ MN +Tcycle_ MN * (MNSwitchOver Pr iority _ U 32 + MNSwitchOverDelay _ U 32)
MNSwitchOverCycleDivider _ U 32

Where: Tcycle_MN is the POWERLINK cycle length (Object NMT_CycleLen_U32)
MNSwitchOverPriority_U32 is the priority of the node at switch-over (the highest priority node shouldtake over the bus when the AMN fails).
MNSwitchOverDelay_U32 is an optional delay added to Tswitch_over_MN to give a lower priority to a node
which is not yet ready to switch-over.
MNSwitchOverCycleDivider_U32 indicate in how many slices the cycle will be divided, the difference
between Tswitch_over_MN for every node will be at least one slice of the cycle time.
The configuration tool shall ensure that all Tswitch_over_MN values for all Nodes are unique.
In addition to the sub-indices of the Object NMT_BootTime_REC defined in the POWERLINK
specification the following sub indices will be implemented in a RMN.

3.5.2.1

Additional(1F89h)sub-indicesin

NMT_BootTime_REC

All these sub-indices shall only be implemented if the MN supports managing node redundancy.

EPSG DS 302-A V1.1.1

•

-31-

Sub-Index 0A: MNSwitchOverPriority_U32
Sub-Index

0A

Name

MNSwitchOverPriority_U32

Data TypeUNSIGNED32

Category

Cond

Value Range

UNSIGNED32

Accessrw, valid on reset

Default Value

NodeID_U8 – 2405

PDO
Mapping

No

This sub-index describes the priority that the RMN will have during switch-over (in case of AMN
failure). Value 1 is the highest priority value for MNSwitchOverPriority_U32. Value of
MNSwitchOverPriority_U32 shall be strictly greater than 0, otherwise no priority should be assigned.
•

Sub-Index 0B: MNSwitchOverDelay_U32
Sub-Index

0B

Name

MNSwitchOverDelay_U32

Data TypeUNSIGNED32

Category

Cond

Value Range

UNSIGNED32

Accessrw, valid on reset

Default Value

10

PDO
Mapping

No

This sub-index lowers the priority of a RMN in the case that the node is not in the state
NMT_CS_OPERATIONAL.
•

Sub-Index 0C: MNSwitchOverCycleDivider _U32
Sub-Index

0C

Name

MNSwitchOverCycleDivider _U32

Data TypeUNSIGNED32

Category

Cond

Value Range

UNSIGNED32

Accessrw, valid on reset

Default Value

10

PDO
Mapping

No

This POWERLINK cycle will be divided in MNSwitchOverCycleDivider_U32 slices. This slice will be
the minimum difference between two Tswitch_over_MN.
By default the POWERLINK cycle is divided in 10 slices (one slice per RMN, which by default have
Node-Id from 241 to 250).

3.5.3

ActiveManagingNodeIndication (AMNI) frame

ActiveManagingNodeIndication (AMNI) is a new POWERLINK frame. It is sent by a RMN to inform allother RMN that there it will be the new AMN on the bus at the next start of cycle. Upon reception ofthis frame, other SMN will have to restart their detection timer as if they received a SoC.
This message can be sent only if no more frames are detected on the POWERLINK network. It shallbe noticed that AMNI is a frame that is not explicitely requested by the AMN as all the other frames but
a frame that is sent out autonomously by a RMN.

5 If the configuration tool does not manage RMN priorities, the RMN shall have their Node-Id from 241 to 250. The Node-Id will

be used as a priority differentiator.

EPSG DS 302-A V1.1.1-32-

Bit Offset
Octet Offset6

7

0

Res

6

5

4

3

2

1

0

res

res

res

Message Type1

Destination2source

3

res

4

res

res

5

res

res

res

res

res

res

res

6

Reserved

7

Reserved

8

Reserved

9

Reserved

Tab. 5AMNI frame structure

Field

Abbr

Description

Message Type

mtyp

POWERLINK
identification

Destination

dest

POWERLINK node ID of the addressed
node(s)

C_ADR_BROADCAST

Sourcesrc

POWERLINK node ID of the transmittingnode

RMN NodeID

Tab. 6AMNI frame data fields

Valuemessage

type

AMNI (07h)

A MAC multicast address is assigned to AMNI, such as described in the following table.

Active Managing Node Indication (AMNI)
Tab. 7

3.5.4

MAC-Multicast address

Value

C_DLL_MULTICAST_AMNI

01.11.1E.00.00.05

Assigned multicast address

Example with default values

In this example, we have 3 RMN (POWERLINK node-ID 241, 242, 243). Node-ID 241 was the AMN, it
fails and we consider that Node-Id 242 is not ready to switch-over (not in state
NMT_CS_OPERATIONAL)

Tswitch _ over _ MN 241 = Tcycle _ MN +Tswitch _ over _ MN 242 = Tcycle _ MN +Tswitch _ over _ MN 243 = Tcycle _ MN +Tcycle _ MN * (1 + 0)

= Tcycle _ MN +10
Tcycle _ MN * (2 + 10)
10
Tcycle _ MN * (3 + 0)

10

Tcycle _ MN *1
10= Tcycle _ MN += Tcycle _ MN +Tcycle _ MN *12
10Tcycle _ MN * 3
106 Octet offset refers to the start of the POWERLINK frame. Offset to the start of the Ethernet frame is 14 octets.

EPSG DS 302-A V1.1.1

SoC
from
241

-33-

No AMNISoC from
243

SoC
from
243

SoC
from
243

Tswitch- over RMN 242
Timer cancelled

Tswitch- over RMN 243

Timeout for
NodeID 243

Fig. 18.

3.5.5

Example of switch-over with default priorities

Example with configured values

In this example, we have 3 RMN (POWERLINK node-ID 241, 242, 2437). RMN241 was the AMN andit failed. Then the election mechanism is run.
Configuration values:
RMN241o
MNSwitchOverPriority_U32 = 1oMNSwitchOverCycleDivider _U32 = 3
RMN242o
MNSwitchOverPriority_U32 = 2oMNSwitchOverCycleDivider _U32 = 3
RMN243o
MNSwitchOverPriority_U32 = 3oMNSwitchOverCycleDivider _U32 = 3

T* (1 + 0)
T*1
Tswitch _ over _ MN 241 = Tcycle _ MN + cycle _ MN
= Tcycle _ MN + cycle _ MN3
3
T
* (2 + 0)
T*2
Tswitch _ over _ MN 242 = Tcycle _ MN + cycle _ MN
= Tcycle _ MN + cycle _ MN3
3
T
* (3 + 0)
T*3
Tswitch _ over _ MN 243 = Tcycle _ MN + cycle _ MN
= Tcycle _ MN + cycle _ MN
3
3

EPSG DS 302-A V1.1.1

SoC
from 241

-34-

No
SoC

AMNI
from 242

SoC
from 242

SoC
from 242

T Switch over RMN243
Timer cancelled

T Switch over RMN242

Timeout for RMN242

Fig. 19.

Example of switch-over with configured priorities

Example with large configured values

3.5.6

In this example, we have 3 RMN (POWERLINK node-ID 241, 242, 243). RMN241 was the AMN and it
failed. Then the election mechanism is run.
In this example there are large timeout values defined.
Configuration values:
RMN1o
MNSwitchOverPriority_U32 = 9oMNSwitchOverCycleDivider _U32 = 4
RMN2o
MNSwitchOverPriority_U32 = 10o
MNSwitchOverCycleDivider _U32 = 4
RMN3o
MNSwitchOverPriority_U32 = 11o
MNSwitchOverCycleDivider _U32 = 4

T* (9 + 0)T*9Tswitch _ over _ MN1 = Tcycle _ MN + cycle _ MN
= Tcycle _ MN + cycle _ MN44T
* (10 + 0)T
*10
Tswitch _ over _ MN 2 = Tcycle _ MN + cycle _ MN
= Tcycle _ MN + cycle _ MN44T
* (11 + 0)T
*11
Tswitch _ over _ MN 3 = Tcycle _ MN + cycle _ MN
= Tcycle _ MN + cycle _ MN
4
4
SoC
from 241

No
SoC

No
SoC

No
SoC

SoC
AMNI
from 242 from 242

T Switch over RMN243
Timer cancelled

T Switch over RMN242

Timeout for RMN242

SoC
from 242

EPSG DS 302-A V1.1.1

Fig. 20.

-35-

Example of switch-over with configured large priorities

Switch-over required by the application

3.6

The application shall be able to require an AMN to switch-over. It shall be possible to ask the local
node or a remote node to go to standby.
The application could force the local node (AMN) to go to standby. In that case the election
mechanism defined in 3.5 will ensure that the most priority node will switch-over to active state.
The application could ask a remote node (AMN) to go to standby. In that case, the application on the
SMN will use the NMT State Command Services to send the NMTGoToStandby NMT state commandto the AMN. The remote node shall be able to reject the remote request NMTGoToStandby. In thatcase the AMN continues acting as an AMN.
NMTCommandID

M/O

Initial state

Destination state

NMTGoToStandbyO

NMT_RMS_ACTIVE_EPL_MODE
Substate
NMT_MS_PRE_OPERATIONAL_1 /NMT_MS_PRE_OPERATIONAL_2 /NMT_MS_READY_TO_OPERATENMT_RMS_ACTIVE_EPL_MODE
Substate
NMT_MS_OPERATIONAL

NMT_RMS_STANDBY_EPL_MODE
Substate
NMT_CS_PRE_OPERATIONAL_1

Tab. 8Additional plain NMT state commandName

ID Value

NMTGoToStandby

2Ch

Tab. 9

NMT_RMS_STANDBY_EPL_MODE
Substate
NMT_CS_OPERATIONAL

Addtional NMT Command ID

The NMTGoToStandby service contains a Delay Flag (DF). If this flag is set the recipient shall include
the optional delay MNSwitchOverDelay_U32 into its switch-over time computation. It will allow a SMN
to put an AMN in standby state, even if its priority is the highest in the network at this time.
Bit offset
Octet offset

7

6

5

0

4

3

2

Reserved

10DFTab. 10

NMTCommandData structure of NMTGoToStandby

Field

Abbr.

Description

Value

Delay Flag

DF

Indicates if the recipient shall include the optional
delay MNSwitchOverDelay_U32 into its switch-overtime computation

TRUE (1) / FALSE (0)Tab. 11

NMTCommand data fields of NMTGoToStandby

3.7

POWERLINK Cycle Timing

In the following example, two RMNs and one Controlled Node are present on the POWERLINK
network. On failure of RMN 241, the RMN 242 becomes AMN.

EPSG DS 302-A V1.1.1-36-

RedundantManaging Node(Active State)
EPL Node ID=
241 & 240

RedundantManaging Node
(In Failure)
EPL Node ID= 241

RedundantManaging Node
(Standby State)
EPL Node ID =242

Fig. 21.

Failure of
MN 241

RedundantManaging Node(Active State)
EPL Node ID=
242 & 240

Controlled
NodeControlled
Node

EPL Node Id = 1

EPL Node Id = 1

POWERLINK Network timing constraints
MN241

CN1

SoC

MN242

Tpropag _241_1

SoC

SoC

Tpropag _241_242

Tcycle _MN

Tcycle_MN

Active MN 241 fails

SoC

SoC

AMNI

SoC

TSwitch- over_MN242

Tpropag _242_1

Tcycle_MN

SoC

AMNI

Tcycle_MN

SoC

JitterFig. 22.

POWERLINK switch-over timing in isochronous phase

EPSG DS 302-A V1.1.1-37-

Note: Jitter: The cycle periodicity will be kept after the switch-over. But the new AMN will potentiallynot be at the same location than the previous one. Then a jitter will be introduced in the SoC of thefirst cycle produced by the new AMN. The CN shall be robust to this jitter. The maximum value of thisjitter can be considered as equal to the maximum propagation time between all nodes.

Flag in SoA frame

3.8

The presence of managing node redundancy shall be signalled by the AMN with a flag in the SoA
frame.
Note: The byte 9 of this POWERLINK frame is the 23 th byte in the Ethernet frame (not including 8
bytes of preamble)
Bit Offset
Octet Offset

7

0

Res

6

5

Destination2source3

NMTStatus

4

res

res

5

res

res

res

res

res

1

0

xx/resxx/res

res

res

res

6

RequestedServiceID

7

RequestedServiceTarget

8

EPLVersion
res2

Message Type

res

res

10-45

res

xx

xx

xx

MR

reserved
POWERLINK SoA frame structure

Field
Managing
Node
Redundancy
Tab. 133

1

9Tab. 12

4

Abbr
MR

Description
Flag: Managing node redundacy is
configured on the MN(s)Additional flags in SoA

Value
0…no MN redundancy
1…MN redundancy activeEPSG DS 302-A V1.1.1

4

-38-

Ring Redundancy

The ring redundancy is able to detect and cope with a single point of medium failure.
The redundancy is just achieved by a special MN interface using two ports. Any CN may be usedwithout additional hardware.

4.1

Topology and Functional Description

The redundant ring topology requires a line topology. However, the end of the line returns to thesecond port of the MN.
Under normal conditions the MN will only transmit and receive data on the first port. On the other port
the MN monitors the frame reception to verify that the ring is “closed”.
Managing NodeFig. 23.

HubControlled Node

Hub1

Controlled Node

Hub2

Controlled Node

Redundant ring topology

In case of medium failure the ring is “opened”. At this time the MN will not receive frames on thesecond port, that have been sent by itself. Then the MN will transmit and receive on both ports. PRes
frames will have to be propagated to the other port to allow CN to CN communication, i.e. the two
ports act as a standard hub.

EPSG DS 302-A V1.1.1-39-Managing Node

Hub1

Controlled Node

Hub2

Controlled Node

Hub

Cable break

Fig. 24.

Controlled Node“Open” Ring

If the ring is closed again, collisions will occur on the network. If such collisions are detected by the
MN it shall stop transmitting frames on the second port immediately.

Ring Redundancy Status

4.2

The Managing Node shall provide information about ring redundancy status to the POWERLINK
nodes, in order to inform the application of a failure. The ring redundancy status information will be
introduced inside POWERLINK SoA frames.
The bits 2 and 3 of byte 9 shall be used in the following message to show that ring redundancy ispresent in the network:•

SoA

A Managing Node that supports ring redundancy shall include the following information inside the SoA
frame.
Bit 2
Bit 3= Ring Redundancy (RR)
= Ring Redundancy status (RRstat)(0 = no ring redundancy, 1 = ring redundancy)(0 = ring ok, 1 = ring broken - failure)Note: The byte 9 of this POWERLINK frame is the 23 th byte in the Ethernet frame (not including 8
bytes of preamble)

EPSG DS 302-A V1.1.1-40-

Bit Offset
Octet Offset

7

0

Res

6

5

4

Destination2source3

NMTStatus

4

res

res

5

res

res

res

res

res

1

0

xx/resxx/res

res

res

res

6

RequestedServiceID

7

RequestedServiceTarget

8

EPLVersion
res2

Message Type

1

9

res

res

res

10-45
Tab. 14

3

RRstatRR

xx

xx

reserved
POWERLINK SoA frame structure

4.3

Additional Object Description

4.3.1

Object 1F82h: NMT_FeatureFlags_U32

The Feature Flags indicate communication profile specific properties of the device given by its design.
The object shall be setup by the device firmware during system initialisation.
Octet Bit
2
17

Name
Ring Redundancy

Tab. 15

Ring Redundancy NMT_FeatureFlags_U32 additional bit interpretation

4.3.2

TRUE
MN
supports
redundancy

FALSE
ring MN does not support ring
redundancy

Object 1C40h: DLL_MNRingRedundancy_REC

This object enables the ring redundancy of the managing node. It shall only be implemented if the
managing node supports the feature.
The object should be set by the system configuration.

EPSG DS 302-A V1.1.1

Index
Name
Data Type•

1C40h
DLL_MNRingRedundancy_REC
DLL_MNRingRedundancy_TYPE

Object CodeRECORD

Category

Cond

AccessPDO Mapping

const
No

Category
AccessPDO Mapping

M
rw
No

Sub-Index 00h: NumberOfEntries
Sub-Index
Name
Value Range
Default Value

•

-41-

00h
NumberOfEntries2
2

Sub-Index 01h: MNRingRedundancyEnable_U8
Sub-Index
Name
Data Type
Value Range
Default Value01h
MNRingRedundancyEnable_U8
UNSIGNED8
0 (FALSE), ≠0 (TRUE)
0 (FALSE)

This sub-index enables the ring redundancy. If the value is FALSE the ports of the managing
node work like a hub. If the value is TRUE the hub is disabled and the second port is able todetect a broken line.
•

Sub-Index 02h: MNRingRedundancyStatus_U8
Sub-Index
Name
Data Type
Value Range
Default Value01h
MNRingRedundancyStatus_U8
UNSIGNED8
0 (ok), ≠0 (error)
0

Category
AccessPDO Mapping

O
ro
No

This sub-index holds information on the medium failure.
If the value is OK the ring is “closed”. The Managing node is just monitoring the incoming
frames on the second port.
If it is not OK the ring is “open”. The ports of the Managing Node work like a hub.

Object 043Bh: DLL_MNRingRedundancy_TYPE

4.3.3
Index
Name

043Bh
DLL_MNRingRedundancy_TYPE

Object TypeDEFSTRUCT

Sub-Index
00h
01h
02h

Component Name
NumberOfEntries
MNRingRedundancyEnable_U8
MNRingRedundancyStatus_U8

Value
02h
0002h
0002h

Data TypeUNSIGNED8UNSIGNED8EPSG DS 302-A V1.1.1

App. 1-42-

Device Description Entries (normative)

Additional device description entries:
Name
D_NMT_MNRedundancy_BOOL
D_DLL_MNRingRedundancy_BOOL

end-of-file

Description
Ability of a MN to perform managing node redundancy functions
Ability of a MN to perform ring redundancy functions

Type
BOOLEANBOOLEAN

Category
MN
CN
M
M
-

Default
MN
N
N

CN-