KPA EtherCAT Master Stack Architecture

EtherCAT master stack has a modular structure to respond to a challenge of each particular implementation. It makes the master scalable to fit the size of application, portable to different operating systems, adaptable to various hardware platforms and allows developing or customizing each module separately while keeping the functionality of the others intact.

Master’s modules are grouped in the following layers, thereby all functions are clearly separated:

Application layer

Application layer is responsible for interaction with various programming or/and configuration environments and other applications or devices. It encapsulates and

• ensures access to master’s functions from the side of applications or process tasks
• allows interaction with the master by means of Remote Procedure Calls service and provides TCP/IP or/and UDP connections, for example, for mailbox communication with slaves via UDP

KPA EtherCAT Master Stack Core

Mailbox module

KPA Master Core mailbox module deploys protocols to handle service data objects (SDP), data transfer and data exchange. The following protocols – according to the EtherCAT standard – are already supported:

• CAN application protocol over EtherCAT (CoE)
• Ethernet over EtherCAT (EoE)
• Servo Profile over EtherCAT (SoE)
• File Access over EtherCAT (FoE)
• Vendor specific Profile over EtherCAT (VoE)
• ADS over EtherCAT (AoE)

Process Image Module

Process Image addresses are provided by EtherCAT network information (ENI) file, generated by a configuration tool. Access to the process image from control/process tasks is carried out through the master interface.

Distributed Clocks Module

Frame Scheduler Module – Different Scan Rates for PDO

In the configuration tool the user defines scan rates for each slave individually. Frame Scheduler module manages velocity of EtherCAT frames by forwarding them to EtherCAT network driver.

KPA EtherCAT Master Stack OSAL

Operating System abstraction layer (OSAL)

Master Stack OSAL allows making the master portable to any operating system with less effort.

The layer consists of two modules:

• OS functions module contains wrappers for OS-dependent functions that deal with threads, timers, mutexes, etc.
• Network adapter driver module that abstracts the master stack core from the underlying network implementation.

KPA EtherCAT Master Operating Systems

Notes: Some OSes like Windows XP, CE6/7, OnTime RTOS-32, PikeOS, RTAI are ported, but not actively supported. Any other OS can be supported on request.

KPA EtherCAT Master Stack Benchmark

Config “Simple”:
64Bytes Frame, 1 LRD / 1 LWR, No DC, No Mailbox (EK1100 – EL1004 – EL2004)

Config “Complex”:
1 Full frame (1514Bytes frame for PDO), LRD / LWR commands, DC, Mailbox via EVENT (EK1100-EL1004-EL2004-EL1252-EL3102-EL4102-EL6751-EL6751)

Test Platform:
CPU: Intel® Core i7-3770 CPU 3.40 GHz 3.39GHz
NIC: Intel® Gigabit CT desktop adapter
RAM: 8GB

1. Comparing Master performance results running on different RTOSes but on the same target Intel Core i7 (Single CPU core for all Master threads)

Master cycle time, µs	100	100	100	100	100
Jitter, ±µs	5	2	7	10	1
Slave response time (avg), µs	43	32	43	33	22
CPU load (avg), %	16	21	21	21	13,3

Config “Complex”:

Master cycle time, µs	200	200	200	200	200
Jitter, ±µs	4	2	3	4	1
Slave response time (avg), µs	170	150	171	166	154
CPU load (avg), %	10	12	13	13	3,8

2. Best Master performance results running on different RTOSes but on the same target (Single CPU core for all Master threads)

Config “Simple”:

Master cycle time, µs	50	50	100	100	50
Jitter, ±µs	10	3	7	10	1
Slave response time (avg), µs	43	32	43	33	22
CPU load (avg), %	31	41	21	21	27,5

Master cycle time, µs	200	200	200	200	200
Jitter, ±µs	4	2	3	4	1
Slave response time (avg), µs	170	150	171	166	154
CPU load (avg), %	10	12	13	13	3,8

KPA EtherCAT Master Stack Packages

Master Classes

KPA EtherCAT Master can be delivered as a standard or customized feature package subject to customer’s demands. Two standard packages are available in accordance with ETG.1500 requirements: Class A (Standard package) and Class B (Basic package). Besides, koenig-pa offers additional type package for the most demanding customers – Premium, with several advanced features already included.

To compare the features and options included in Basic (Class B) and Standard (Class A) packages, refer to the following document.

  KPA EtherCAT Master Classes Flyer (361.7 KiB, 1,568 hits)

Extensions

Extensions are advanced functional options (Feature Packs in terms of ETG) that can be purchased separately and added to any Class of KPA EtherCAT Master. Currently, the following extensions are available:

• Cable Redundancy (available in Premium by default)
• Hot Connect (available in Premium by default)
• TCP/UDP Mailbox Gateway (available in Premium by default)
• External DC Synchronization
• Multi-Master
• CAN DBC driver
• Online configuration
• Process Image logger
• Master Redundancy
• VCOM driver

Online Configuration

KPA EtherCAT Master can detect network topology changes and automatically configure slave devices using a library of user-defined slave configuration files (uESI).

Master Redundancy

Several EtherCAT Masters can co-exist in a network segment, providing backup for seamless EtherCAT operation during possible Master failures. It significantly increases reliability and fault tolerance while reducing downtime.

WebSocket / OPC UA support

Master configuration and variables are available for external applications and services via several well-known protocols including WebSocket and OPC UA.

Process Image Logging + MATLAB / LabView integration

Process Image can be logged for further analysis. MATLAB integration and LabView-compatible (TDMS format) data logging are already implemented, with more applications and formats to come. This feature is extremely useful for throughput-sensitive data acquiring applications.

Operating Systems

We offer EtherCAT Master packages for the following general-purpose and real-time operating systems:

• Windows 7
• INtime
• Linux RT Preemt
• Xenomai
• QNX
• RTX/RTX64
• VxWorks
• Integrity
• FreeRTOS
• Nucleus

Any other operating system can be supported upon customer’s request. Additionally, we have ported KPA EtherCAT Master to Windows XP, CE6/7, OnTime RTOS-32, PikeOS, RTAI, etc. but are not actively support these operating systems.