Ethernet POWERLINK. Performance Examples EPSG. Version (Ethernet POWERLINK Standardisation Group)

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1 Ethernet POWERLINK Performance Examples Version Ethernet POWERLINK Performance Examples Version EPSG (Ethernet POWERLINK Standardisation Group) 2008

2 Performace Examples V EPSG (Ethernet POWERLINK Standardisation Group) POWERLINK-Office of the EPSG Schaperstrasse 18 D Berlin Germany Phone Fax info@ethernet-powerlink.org

3 Performace Examples V Pre. 1 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, or compensatory, 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 of merchantability or fitness for a specific purpose, or that the use of the material contained herein is free from 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 is subject 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 edition of 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 to perform any duty owed by any other person or entity to another. Any person utilizing this, and any other EPSG Standards document, should rely upon the advice of a competent professional in determining 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 it s members are not able to provide an instant response to interpretation requests except in those cases where the matter has previously received formal consideration. Comments for revision of EPSG Standards are welcome from any interested party, regardless of membership affiliation with the EPSG. Suggestions for changes in documents should be in the form of a proposed change of text, together with appropriate supporting comments. Comments on standards and requests for interpretations should be addressed to: POWERLINK-Office of the EPSG, Schaperstrasse 18, D Berlin, Germany Pre. 1.1 Patent notice Attention 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 the existence or validity of any patent rights in connection therewith. The EPSG 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.

4 Performace Examples V Pre. 2 History Vers. Date Author / Filename Description Schönegger/Kirchmayer B&R Created (extracted from DS301 V1.0.0) EPSG_PerformanceExamples-V doc Kirchmayer B&R Typo in calculation of t AsyncMax corrected. EPSG_PerformanceExamples-V doc Editorial Remarks: notes, examples, hints, etc. are marked by cursive

5 Performace Examples V Pre. 3 Content Pre. 1 Disclaimer 3 Pre. 1.1 Patent notice 3 Pre. 2 History 4 Pre. 3 Content 5 Pre. 4 Figures 6 Pre. 5 Definitions and Abbreviations 7 Pre. 5.1 Definitions 7 Pre. 5.2 Abbreviations 8 1 General Ethernet POWERLINK Network Timing 10 2 Examples Timing values Overview Node Drives Example machine topology The Main Module The machine module Example 1a Calculating the average hub depth Calculation of cycle time Performance Example 1b Average hub depth Calculation of Cycle time Performance Example 2a Large Machine Average hub depth Calculation of cycle time Performance Example 2b Average hub depth Calculation of Cycle time Performance Example 2c Average hub depth Calculation of Cycle time Performance 24

6 Performace Examples V Pre. 4 Figures Fig. 1. Ethernet POWERLINK network timing 10 Fig. 2. The main module 12 Fig. 3. A single machine module 13 Fig. 4. Example machine configuration 1a 14 Fig. 5. Example machine configuration 1b 17 Fig. 6. Example machine configuration 2a 19 Fig. 7. Example machine configuration 2b 21 Fig. 8. Example machine configuration 2c 23

7 Performace Examples V Pre. 5 Definitions and Abbreviations Pre. 5.1 Definitions Asynchronous Data Data in an POWERLINK network which is not time critical. Within the POWERLINK cycle there is a specific period reserved for Asynchronous Data which is shared by all nodes. Each node connected to the network can send asynchronous data by requesting it to the Managing Node. The Managing Node keeps a list of all asynchronous data requests and will subsequently grant the network access to one node after the other. Asynchronous Periode The Asynchronous Period is the second part of the POWERLINK cycle, starting with a Start of Asynchronous (SoA) frame. Asynchronous Scheduling The MN s asynchronous scheduler decides when a requested asynchronous data transfer will happen. Continuous Continuous is an POWERLINK communication class where isochronous communication takes place every cycle (the opposite to multiplexed). Controlled Node (CN) Node in an POWERLINK network without the abilty to manage the SCNM mechanism. Cycle State Machine The Cycle State Machine controls the POWERLINK cycle on the Data Link Layer and is itself controlled by the NMT state machine defining the current operating mode. Cycle Time The time between two consecutive Start of Cyclic (SoC) frames i.e. repeating process. The Cycle Time includes the time for data transmission and some idle time before the beginning of the next cycle. Deterministic Communication POWERLINK Layer POWERLINK Cycle Command Describes a communication process whose timing behaviour can be predicted exactly. I.e. the time when a message reaches the recipient is predictable. The POWERLINK Command Layer defines commands to access parameters of the object dictionary. This layer is on top of the Sequence Layer and distinguishes between an expedited and a block transfer. Data exchange within an POWERLINK network is structured in fix intervals, called cycles. The cycle is subdivided into the isochronous and the asynchronous period and is organized by the MN. POWERLINK Mode The POWERLINK Mode includes all NMT states in which POWERLINK cycles are run. POWERLINK Node ID Each POWERLINK node (MN, CN and Router) is addressed by an 8 bit POWERLINK Node ID on the POWERLINK layer. This ID has only local significance (i.e. it is unique within an POWERLINK segment). Ethernet POWERLINK An extension to Legacy Ethernet on layer 2, to exchange data under (POWERLINK) hard real-time constraints. It was developed for deterministic data exchange, short cycle time and isochronous operation in industrial automation. Idle Period The Idle Period is time interval remaining between the completed asynchronous period and the beginning of the next cycle. Isochronous Pertains to processes that require timing coordination to be successful. Isochronous data transfer ensures that data flows continously and at a steady rate in close timing with the ability of connected devices. Isochronous Data Data in an POWERLINK network which is to be transmitted every cycle (or every nth cycle in case of multiplexed isochronous data).

8 Performace Examples V Isochronous Period Legacy Ethernet Managing Node (MN) Media Access Control (MAC) Multiplexed Multiplexed CN Multiplexed Timeslot Network (NMT) NMT State Machine PollRequest PollResponse Management Process Data Object (PDO) POWERLINK Mode Service Data Object (SDO) Sequence Layer Slot Network (SCNM) Pre. 5.2 ASnd CN EPSG ID IP MAC MN NMT Communication Management The Isochronous Period of an POWERLINK cycle offers deterministic operation, i.e. it is reserved for the exchange of (continuous or multiplexed) isochronous data. Ethernet as standardised in IEEE (non-deterministic operation in non-time-critical environments). A node capable to manage the SCNM mechanism in an POWERLINK network. One of the sub-layers of the Data Link Layer in the POWERLINK reference model that controls who gets access to the medium to send a message. Multiplexed is an POWERLINK communication class where cyclic communication takes place in such a way that m nodes are served in s cycles (the opposite to continuous). A node which is allowed to send isochronous data every n th cycle. A slot destined to carry multiplexed isochronous data, i.e. the timeslot is shared among multiple nodes. Network Management functions and services in the POWERLINK model. It performs initialisation, configuration and error handling in an POWERLINK network. The state machine controlling the overall operating mode and status of an POWERLINK node. A PollRequest is frame, which is used in the isochronous part of the cyclic communication. The MN request with this frame the CN to send its data. A PollResponse is frame, which is used in the isochronous part of the cyclic communication. The CN responses with this frame to a PollRequest frame from a MN. Object for isochronous data exchange between POWERLINK nodes. The POWERLINK Mode provides isochronous communication and asynchronous communication. The nodes are synchronized with a dedicated POWERLINK frame, which has an extremely low jitter. Peer to peer communication with access to the object dictionary of a device. The POWERLINK Sequence Layer provides the service of a reliable bidirectional connection that guarantees that no messages are lost or duplicated and that all messages arrive in the correct order. In an POWERLINK network, the managing node allocates data transfer time for data from each node in a cyclic manner within a guaranteed cycle time. Within each cycle there are slots for Isochronous Data, as well as for Asynchronous Data for ad-hoc communication. The SCNM mechanism ensures that there are no collisions during physical network access of any of the networked nodes thus providing deterministic communication via Legacy Ethernet. Abbreviations Asynchronous Send (POWERLINK frame type) POWERLINK Controlled Node Ethernet POWERLINK Standardisation Group Identifier Internet Protocol Media Access Control POWERLINK Managing Node Network Management

9 Performace Examples V PDO PReq PRes SCNM SDO SoA SoC TCP UDP Process Data Object PollRequest (POWERLINK frame type) PollResponse (POWERLINK frame type) Slot Communication Network Management Service Data Object Start of Asynchronous (POWERLINK frame type) Start of Cyclic (POWERLINK frame type) Transmission Control Protocol User Datagram Protocol

10 Performace Examples V General The content of this chapter is for information only. The calculation of basic network parameters is explained with several examples. 1.1 Ethernet POWERLINK Network Timing For a detailed timing description see Chapter Data Link Layer POWERLINK Mode /Section POWERLINK Cycle Timing. Managing Node (MN) t cycle_mn t PReq_CN1_MN t PResTx_CN1 t PRes-PReq_MN t PRes-PRes_MN t PRes-SoA_MN t PReq_CN2_MN t PResTx_CN2 t PResTx_MN t SoA t SoA-AsndRx_MN o. t SoA-AsndTx_MN SoC PReq PReq PRes SoA * PRes PRes ASnd t SoC t SoC-PReq_MN t PReq-PRes_CN1 tpreq-pres_cn2 t ASndTx o. t ASndRx t AsyncMax Controlled Node (CN) time * t ASndRx-SoC_MN o. t ASndRx-SoC_CNi Fig. 1. Ethernet POWERLINK network timing t AsyncMax is defined as the time which is in worst case needed for asynchronous communication. Because every node needs some time for processing of ASnd Frames t AsyncMax reaches behind the ASnd Frame, this is accounted for by the parameters t ASndRx-SoC_MN and t ASndRx-SoC_CNi. t AsyncMax is calculated using the following formulas. Time without the ASnd Frame, if sent by CN: t AsyncMaxOverhCN t P Re s SoA_ MN t SoA ASndRx _ MN Time without the ASnd Frame, if sent by MN: t AsyncMaxOverhMN Put together: t P Re s SoA _ MN t SoA ASndTx _ MN t max( t AsyncMaxOverh t t SoA SoA max( t AsyncMaxOverhCN max( t, t t t t AsyncMax AsyncMaxOverh ASndRx ASndRx SoC _ MN ASndRx SoC _ MN AsyncMaxOverhMN ) allcn, max( t i allcn, max( t i ASndRx SoC _ CNi ASndRx SoC _ CNi t AsndRx = t AsndTx is the time a asynchronous frame of maximum length (configurable) needs, plus the maximum (worst case) signal propagation between the MN and the CNs. The values used to calculate cycle times are parameters of an POWERLINK implementation. Every POWERLINK MN or CN implementation will provide fixed values for these parameters. )) ))

11 Performace Examples V Examples 2.1 Timing values The following examples show how to calculate achievable cycle times. The timing values used are taken from actual implementations. t Start = t SoC + t SoC-PReq_MN 26µs t AsyncMaxOverht = 32µs t PReq-PRes_CNi 1µs + 2 times the signal propagation time t PRes-PReq_MN 1µs t AsndRx 120µs plus maximum signal propagation Additional parameters for calculating t PRq-PRs t HubDelay ns (460ns + 40ns jitter) The t PReq-PRes_CNi parameters can be calculated using a simplified procedure. Instead of determine this value for every station independently the average hub depth is calculated. For this take the number of hubs on the path from the MN to a certain CN, sum these hub depths and divide by the number of POWERLINK stations. 2.2 Overview We consider a configuration where a machine is built up by using a number of nodes and a number of drives Node An node is considered a modular System which can flexibly expanded with modules to get the amount of digital and analog in- and outputs needed. For this example every IO Node shall provide: analog inputs (INTEGER16) 10 analog outputs (INTEGER16) 10 digital inputs (BOOLEAN) 128 digital outputs (BOOLEAN) 128 For this the necessary POWERLINK frame net data per Node are PollRequest PollResponse Drives 36 bytes 36 bytes 16 byte total for 4, freely configurable, 32 bit PDO values plus 20 bytes for SDO data embedded in PDO, for very fast command interface. Necessary net data per drive station are PollRequest PollResponse 36 bytes 36 bytes

12 Performace Examples V Example machine topology The following examles are based on typical automation network topologies in machine building. A modular concept has been used with a main module and several machine modules each consisting of multiple PLCs, s and drives The Main Module The main module contains drives and s (1-3) for the main shaft and supervisory control. It supports a maximum of three additional shafts plus 4 and 5 for optional Input/Output. The module can be controlled autonomously by its own PLC if necessary. Main Module Main Shaft 3 Shaft 1 Shaft 2 Shaft 3 Fig. 2. The main module Drives Up to 4 nodes Up to 5 data points: analog inputs 50 analog outputs 50 digital inputs 640 digital outputs 640

13 Performace Examples V The machine module Each machine module contain four drives and various s. The module can be controlled autonomously by its own PLC if necessary. Fig. 3. A single machine module Drives Up to 4 nodes 1 data points: analog inputs 10 analog outputs 10 digital inputs 128 digital outputs 128

14 Performace Examples V Example 1a The system consists of a central PLC (e.g. Industrial PC) with visualization. A Main module controlling the main shaft and two additional shafts and two machine modules are connected to one central network hub. Additional remote visualization, s and a webcam to supervise parts of the machine are field connected to the machine modules. Main 1 2 Main Shaft 3 Shaft 1 Shaft 2 Hub Remote Visualisation Webcam Fig. 4. Example machine configuration 1a

15 Performace Examples V Technical Data for this configuration: Overall Number of Nodes 20 Drives 11 IO nodes 6 Number of analog data points (a 2 Byte) 120 (60 IN, 60 OUT) Number of digital data points 1536 (768 IN, 768 OUT) Remote Visualization 1 node (async only mode) Camera 1 node (async only mode) Results: POWERLINK cycle time 465 µs 500µs w/o Mux 316µs 350µs w Mux Isochronous Bandwidth µs µs Asynchronous Bandwidth 3 500µs µs Calculating the average hub depth The Hub depth is the amount of hubs traversed in the way from MN to CN, MN and CN not counted. To get the average hub depth count the stations on every hub depth, multiply the number of stations on a hub depth with the depth number, add this figures up and divide the sum by the number of stations. In example 1a there are 3 stations with hub depth 1, 4 stations with hub depth 2, and so on. The average hub depth is used for calculating the length of synchronous communication, therefore the remote visualization and the webcam, which don t participate in synchronous communication, can be left out for this calculation. hub depth #stations sum 17 Calculating the average hub depth gives: (1*3 + 2*4 + 3*4 + 4*3 + 5*2 + 6*1)/19 = 51/17 = Calculation of cycle time We have 36 net bytes in every PollRequest and PollResponse Frame. Add 28 bytes of Frame- Overhead and 8 bytes for Ethernet Preamble gives =72 bytes per frame. With 100 Mbps signal transmission speed a byte needs 80 ns on the wire. Therefore each of these frames needs 5.76 µs. There are 17 cyclic stations (11 and 6 drives) in this configuration, gives 17*5.76*2 = µs transmission time for the frames. To this add the gaps between the frames (t PReq-PRes_CNi and t PRes- PReq_MN), 17 * 2 = 34 µs. And add the propagation delays of the hubs using the average hub depth and t HubDelay, 17*3.0*( ) = 51 µs. Now add up: = µs, this is the cycle time needed for isochronous communication. Now consider start (SoC frame) and end of the cycle (SoA frame + asynchronous communication). t Start is 26 µs (including the SoC frame).

16 Performace Examples V For asynchronous communication consider the asynchronous overhead time t AsyncMaxOverh = 32 µs and a frame up to 1500 byte length (this frame needs 120 µs). So = 152 µs are needed for asynchronous communication. For the propagation delay of the asynchronous frame we consider the maximum hub depth of 6, which gives 6 µs signal propagation delay. The complete cycle time therefore is given by: = µs With most applications it is not even necessary to transfer data of all networked nodes in every cycle. There are rather few nodes which have to communicate their data every cycle (e.g. master axes) and other nodes which can achieve their tasks with much lower cycle times. With muliplexing POWERLINK time slots, the bandwidth utilisation can be further optimised. Suppose this example with 3 nodes which have to send their data every cylce and reserve 5 time slots for isochronous transfer of data of the remaining 14 nodes, a minimum cylce time of 316,16µs can be achieved Performance The Ethernet POWERLINK cycle time for this machine can be set to 466 µs without multiplexing or to 316 µs in multiplex mode. Rounding these numbers to the next multiple of 50 µs which according to realistic cycle times of control loops in servo amplifiers will give 500 µs and 350 µs respectively. Within this cycle all nodes can receive data from all other nodes and the non-multiplexed nodes can send their isochronous data. The isochronous data bandwidth is 2.45 Mbyte/s in non-multiplexed mode and 1.6 Mbyte/s in multiplexed mode. Without any influence on the isochronous communication or timing precision a remaining bandwidth of 3.0MB per second (= 25.7 Mbps) is available for asynchronous communication in non-multiplexed mode and 4.3 Mbyte/s in multiplexed mode.

17 Performace Examples V Example 1b Same as 1a but daisy chain topology. Main 1 2 Main Shaft 3 Shaft 1 Shaft 2 Webca Fig. 5. Example machine configuration 1b

18 Performace Examples V Technical Data for this configuration: Overall Number of Nodes 20 Drives 11 IO nodes 6 Number of analog data points (a 2 Byte) 120 (60 IN, 60 OUT) Number of digital data points 1536 (768 IN, 768 OUT) Remote Visualization 1 node (async only mode) Camera 1 node (async only mode) Results: POWERLINK cycle time 532,8 µs 550 µs w/o Mux µs 400 µs w Mux Isochronous Bandwidth µs µs Asynchronous Bandwidth µs µs Average hub depth Calculating the average hub depth as in example 1a gives 6,53 µs Calculation of Cycle time The calculation of the cycle time is done in the same way as shown in example 1a. The result is µs for non-multiplexed and µs for multiplexed mode Performance The Ethernet POWERLINK cycle time for this machine can be set to 533 µs without multiplexing or to 352 µs in multiplex mode. Rounding these numbers to the next multiple of 50 µs which according to realistic cycle times of control loops in servo amplifiers will give 550 µs and 400 µs respectively. Within this cycle all nodes can receive data from all other nodes and the non-multiplexed nodes can send their isochronous data. The isochronous data bandwidth is 2.2 Mbyte/s in non-multiplexed mode and 1.4 Mbyte/s in multiplexed mode. Without any influence on the isochronous communication or timing precision a remaining bandwidth of 2.7 MB per second is available for asynchronous communication in non-multiplexed mode and 3.75 Mbyte/s in multiplexed mode.

19 Performace Examples V Example 2a Large Machine The system consists of a central PLC (e.g. Industrial PC) with visualisation, one main module, seven machine modules and a TCP/IP data logger connected to one central network hub. Additional remote visualisation, s and a webcam are field connected to the machine modules Example 2a Large Machine (star topology) Remote Visualisatio Main PLC & Visualisation Hub Main Module 4 5 Remote Visualisatio 1 2 Main Shaft 3 Shaft 1 Shaft 2 Shaft 3 Webcam Sensor with Data Logging Remote Visualisatio Fig. 6. Example machine configuration 2a

20 Performace Examples V Technical Data for this configuration: Overall Number of Ethernet POWERLINK Stations 53 Drives 32 IO nodes 16 Number of analog data points (a 2 Byte) 320 (160 IN, 160 OUT) Number of digital data points 4096 (2048 IN, 2048 OUT) Remote Visualizations 3 (async only mode) Camera 1 (async only mode) Data Logger 1 Results: POWERLINK cycle time Isochronous Bandwidth Asynchronous Bandwidth Average hub depth The average hub depth is Calculation of cycle time 999 µs 1ms non-multiplex mode 400 µs multiplex mode ms µs 1.5 1ms µs The calculation of the cycle time is done in the same way as shown in example 1a. The result is 999 µs for non-multiplexed and 400 µs for multiplexed mode (5 non-multiplexed nodes + 8 multiplexed time-slots) Performance The Ethernet POWERLINK cycle time for this machine can be set to 1 ms without multiplexing or to 400 µs in multiplex mode. Within this cycle all nodes can receive data from all other nodes and the non-multiplexed nodes can send their isochronous data. The isochronous data bandwidth is 3.5 Mbyte/s in non-multiplexed mode and 2.2 Mbyte/s in multiplexed mode. Without any influence on the isochronous communication or timing precision a remaining bandwidth of 1.5 MB per second is available for asynchronous communication in non-multiplexed mode and 3.75 Mbyte/s in multiplexed mode.

21 Performace Examples V Example 2b Same as 2a but daisy chain topology. Example 2b Large Machine (daisy-chain topology) Remote Visualisatio Main PLC & Visualisation Main Module 4 5 Remote Visualisatio 1 2 Main Shaft 3 Shaft 1 Shaft 2 Shaft 3 Webcam Sensor with Data Logging Remote Visualisatio Fig. 7. Example machine configuration 2b

22 Performace Examples V Technical Data for this configuration: Overall Number of Ethernet POWERLINK Stations 53 Drives 32 IO nodes 16 Number of analog data points (a 2 Byte) 320 (160 IN, 160 OUT) Number of digital data points 4096 (2048 IN, 2048 OUT) Remote Visualizations 3 (async only mode) Camera 1 (async only mode) Data Logger 1 Results: POWERLINK cycle time 1967 µs 2ms non-multiplex mode 688 µs 700 µs multiplex mode Isochronous Bandwidth ms µs Asynchronous Bandwidth 2 ms µs Average hub depth Calculating the average hub depth as in example 1a gives Calculation of Cycle time The calculation of the cycle time is done in the same way as shown in example 1a. The result is 1967 µs for non-multiplexed and 688 µs for multiplexed mode (5 non-multiplexed nodes + 8 multiplexed time-slots) Performance The Ethernet POWERLINK cycle time for this machine can be set to 2 ms without multiplexing or to 700 µs in multiplex mode. Within this cycle all nodes can receive data from all other nodes and the non-multiplexed nodes can send their isochronous data. The isochronous data bandwidth is 1.76 Mbyte/s in non-multiplexed mode and 1.3 Mbyte/s in multiplexed mode. Without any influence on the isochronous communication or timing precision a remaining bandwidth of 0.75 MB per second is available for asynchronous communication in non-multiplexed mode and 2.14 Mbyte/s in multiplexed mode.

23 Performace Examples V Example 2c Same as 2a but mixed star-/daisy chain topology. Example 2c Large Machine (mixed star & daisy-chain topology through optimized machine modules) Remote Visualisatio Main PLC & Visualisation Main Module 4 5 Remote Visualisatio 1 2 Main Shaft 3 Shaft 1 Shaft 2 Shaft 3 Webcam Sensor with Data Logging Remote Visualisatio Fig. 8. Example machine configuration 2c

24 Performace Examples V Technical Data for this configuration: Overall Number of Ethernet POWERLINK Stations 53 Drives 32 IO nodes 16 Number of analog data points (a 2 Byte) 320 (160 IN, 160 OUT) Number of digital data points 4096 (2048 IN, 2048 OUT) Remote Visualizations 3 (async only mode) Camera 1 (async only mode) Data Logger 1 Results: POWERLINK cycle time 1368 µs 1.4ms non-multiplex mode 509 µs 550 µs multiplex mode Isochronous Bandwidth ms µs Asynchronous Bandwidth ms µs Average hub depth The average hub depth for this example is Calculation of Cycle time The calculation of the cycle time is done in the same way as shown in example 1a. The result is 1368 µs for non-multiplexed and 509 µs for multiplexed mode (5 non-multiplexed nodes + 8 multiplexed time-slots) Performance The Ethernet POWERLINK cycle time for this machine can be set to 1.4 ms without multiplexing or to 550 µs in multiplex mode. Within this cycle all nodes can receive data from all other nodes and the non-multiplexed nodes can send their isochronous data. The isochronous data bandwidth is 2.5 Mbyte/s in non-multiplexed mode and 1.6 Mbyte/s in multiplexed mode. Without any influence on the isochronous communication or timing precision a remaining bandwidth of 1.1 MB per second is available for asynchronous communication in non-multiplexed mode and 2.7 Mbyte/s in multiplexed mode.