Ethernet-based Industrial Communication Protocols

8/10/2019 Ethernet-based Industrial Communication Protocols

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Ethernet-based Industrial Communication

Protocols

Christoph WimmerBusiness Development Manager


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Agenda

Why Ethernet-based Protocols

Overview of Ethernet-based Industrial Protocols

Adding Deterministic I/O to NI PACs


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Agenda





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Why Ethernet: Protocols

Modbus TCP/IP

Traditional Industrial

Protocols

PROFInetPROFIBUS

DeviceNet EtherNet/IP

Modbus

Ethernet Physical

Layer

CanOPEN EtherCAT


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Ethernet Adoption in Industrial

Total Market $630M Ethernet Really Means:

Ethernet/IP

PROFInet

Modbus TCP/IP

Expected Trends in Type of Wireline Infrastructure Networksbeing used in Industrial Facilities

Source: VDC 2006


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Agenda





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Industrial Ethernet and OSI Model

7. Application

6. Presentation

5. Session

4. Transport

3. Network

2. Data Link

1. Physical

Modbus TCP/IPEthernet/IP,

PROFInet, andEtherCAT,

TCP & UDPIP

Ethernet


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Ethernet-based Industrial Protocols

Modbus TCP/IP

EtherCAT

Ethernet/IP Profinet


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Similarities

Reuse layer 1 and 2 of OSI model

What about the other 5 layers?

Define master (scanner) and slave (adapter)devices

Address 1 or more target applications

Non Real Time

Real Time

Hard Real Time


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Application Targets

Non Real Time Uses standard TCP/IP or UDP/IP

Application: PLC to HMI or PLC to SCADA

Real Time

Provides added determinism w/ OTS hardware Application: Control data

Hard Real Time Adds specific hardware to deliver determinism

Application: Distributed Motion


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Where Protocols Fit?

Modbus TCP/IP PROFInet (NRT)* Ethernet/IP

PROFInet (RT)** Ethernet/IP

EtherCAT PROFInet (IRT)**Ethernet/IP CIP

Sync

**Also PROFInet IO*Also PROFInet CBA
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Modbus TCP/IP

EtherCAT



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Modbus TCP/IP Overview

First industrial protocol on Ethernet (introduced 1999)

Based on Modbus developed by Modicon in 1979

Widely adopted and open Ethernet standard

Advantages Uses standard Ethernet (hardware and TCP/IP transport layer)

Open and relatively simple

Disadvantages Not a hard real-time protocol Does not deliver determinism
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Modbus Data Items

Data Item Data Type Modbus Modbus Slave Description ExampleRead Write Read Write

000001065535 Boolean value Yes Yes Yes Yes Accesses single-bit coils. 000001 = {000001}

100001165535 Boolean value Yes No Yes Yes Accesses single-bit discrete inputs. 100002 = {100002}

300001.1365535.16 Boolean value Yes No Yes YesAccesses individual bits of input registers and interpretsthem as logical TRUE or FALSE values. The leastsignificant bit is 1. The most significant bit is 16.

300001.1 = {the firstbit of 300001}

30000136553516-bit

unsignedinteger

Yes No Yes YesAccesses 16-bit input registers as unsigned integersranging from 0 to 65,535.

300001 = {300001}

400001.1465535.16 Boolean value Yes Yes Yes YesAccesses individual bits of holding registers andinterprets them as logical TRUE or FALSE values. Theleast significant bit is 1. The most significant bit is 16.

400002.16 = {the16th bit of 400002}

40000146553516-bit

unsignedinteger

Yes Yes Yes YesAccesses 16-bit holding registers as unsigned integersranging from 0 to 65,535.

400002 = {400002}


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Modbus TCP/IP

EtherCAT



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Functional Principle: Ethernet On the Fly

Analogy Fast Train: Train (Ethernet Frame) does not stop

Even when watching the train through a narrow window one sees the entire train

Car (Sub-telegram) has variable length

One can extract or insert single person (bits) or entire groups even multiple

groups per train

Master

Slave Slave Slave Slave


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Ethernet Frames

EtherCAT commands are transported in the data area of an Ethernetframe and can be coded via a special Ether Type Ether Type is limited to an Ethernet subnet (not relayed by routers)


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Modbus TCP/IP

EtherCAT



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EtherNet/IP Overview

Dominant bus for Rockwell Automation Managed by Open Device Vendors Association (ODVA)

Extends DeviceNET concepts to Ethernet

Advantages Uses Ethernet transport layer (TCP and UDP)

Disadvantages

Can overload networks with UDP messages if note correctly

configured, recommend managed switches with IGMP snooping
http://images.google.com/imgres?imgurl=http://www.wrcakron.com/holocon/EtherNet_IP.jpg&imgrefurl=http://www.wrcakron.com/IEC61499.html&h=71&w=200&sz=20&hl=en&start=1&um=1&tbnid=JVH1sixUYjefgM:&tbnh=37&tbnw=104&prev=/images?q=ethernet/ip+logo&um=1&hl=en&rlz=1T4DMUS_enUS259US259&sa=G


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Device Classes

Slave

Only sends data if requested by a scanner Supports explicit and implicit messaging

Adapter Class

Master Initiate implicit and explicit communicationsScanner Class

Used for set-up or on-demand data transfer Allows data transfer to be initiated by either

device.

Messaging Class


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Communication from LabVIEW to

ControlLogix PLCs

EtherNet/IP

Available for download from NI-Labs (ni.com/labs)


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Modbus TCP/IP

EtherCAT

Ethernet/IP PROFInet


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PROFInet Overview

Dominate bus for Siemens Application protocol that extends PROFIBUS to Ethernet

Managed by PROFIBUS&PROFINET International (PI)

Advantages Supports both standard and deterministic Ethernet traffic

Uses IEEE-1588 and QoS to add determinism

Disadvantages For RT/IRT managed switch with QoS is recommended Switch with ERTEC ASIC for most challenging apps.


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Three Levels

Non Real Time (NRT) PROFINET CBA

For the commissioning of a plant

Range of 100ms

RT (Real-Time) PROFINET CBA and PROFINET IO

IO applications

Up to 10 ms cycle times

IRT (Isochronous Real-Time) PROFINET IO

Applications in drive systems

Cycles time of less than 1ms Source Wikipedia


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PROFInet Network cycle

No Start Period message Clock synchronization via IEEE 1588 & asynchronous

Red portion of the cycle (Isochronous)

Green portion of the cycle (Asynchronous) min 125 ms


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Technology: IEEE-1588

Technology to synchronize distributed clocks

Accuracy based on clock jitter


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HRT: Determinism and Performance

Organization Response Time

(for 100 axles)

Jitter Data Rate

EtherCAT ~ 0.1 ms < 0.1 us 100 Mbits/s

Sercos-III < 0.5 ms < 0.1 us 100 Mbits/sProfinet-IRT < 1 ms < 1 us 100 Mbits/s

Ethernet Powerlink < 1 ms < 1 us 100 Mbits/s

Ethernet/IP ~ 1 ms < 1 us 100 Mbits/s

Table 1. Real-time comparison of the various real-time methodsStandards-Based Real Time Ethernet Now Off-the-Shelf, by Klaus Zwerina

Table 1. Real-time comparison of the various real-time methodsStandards-Based Real Time Ethernet Now Off-the-Shelf, by Klaus Zwerina


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Agenda





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Host Computer

(TCP/IP) NI PXI Systemwith Ethernet Interface

NI cRIO-9074

NI 9144

NI System with Deterministic Distributed I/O

(EtherCAT)

(TCP/IP)

(EtherCAT)

NI cRIO-9074

NI PXI Systemwith Ethernet Interface

NI 9144


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NI Master Controllers

Requirements CompactRIO or PXI RT system with 2 Ethernet ports

NI-Industrial Communications for EtherCAT


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NI 9144 Expansion Chassis

2 Ports for

Daisy-Chaining

8 Slots forC Series

Rugged Chassis -40 to 70C 9-30V Input Hazloc Shock/Vibe


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LabVIEW Experience

{

{

CompactRIOChassis

NI 9144

ExpansionChassis


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Deterministic

Distributed I/O

Demo


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C Series I/O Modules

EASY POWERFUL OPEN

Over 30 analog and digital modules supported All single-point measurements

No waveform support (NI 9233/9234)

Module-to-module and chassis-to-chassissynchronization

Compatibility with different NI chassis


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Questions

Ethernet-based Industrial Communication Protocols

Documents

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