karsten fischer - p+f wirelesshart demo & applications i · • wirelesshart is downward...

THE PEPPERL+FUCHS GROUPWirelessHART Demo & Application Overview

Karsten Fischer - Global Account Manager Invensys

Topics

• Elements of WirelessHART– Network Components– Mesh network– Network Manager– Frequency Hopping– Time Division Multiple Access (TDMA)

• Mesh Network - How it works• WirelessHART Network

– Network ID– How to form a Network

• WirelessHART & Safety• Field Device Functionality• Questions & Answers• Application Examples

Elements of WirelessHART

WiredInterface

WirelessHARTNetwork

WH-Gateway-Network Manager-Network Access Point

WH-Adaptor

Field-Device

Wireless Transmission


• Identified disadvantages of WirelessHART in an industrial plant application were overcome by an intelligent communication management…

• The solutions for WirelessHART are:– Mesh Network– Network Management– Frequency Hopping– Time Division Multiple Access (TDMA)

• A reliable network solution in result then requires special capabilities in the WirelessHART Gateway

Elements of WirelessHART - Mesh Network

• Mesh Network– Each participant is working as a “repeater”

• increased communication area• max. distance (best case!) between 2 participants 200 m / Line of

Sight • The more participants the more stable is the network• Best practice is that each gateway has at least 5 neighbors and

that each field device has at least three neighbors in closer distance

– Broken paths are detoured which increases transmission reliability• The network is a self healing network

– New participants will be integrated automatically

Elements of WirelessHART - Network Management

• Network Management– The Network is organized and controlled by a central component, the

Network Manager– The Network Manager

• forms the Network• determines the communication paths between all participants• as well as alternative paths and timings

– Newly added participants are added to the network automatically• the network manager will organize itself after initial startup and

will get more and more reliable after a short while when it has identified all neighbors and participants in the closer range of the network.

Elements of WirelessHART - Frequency Hopping

• Frequency Hopping– IEEE 802.15.4 allows 16 Channels (known from WLAN)– WirelessHART switches through these 16 Channels– Already occupied channels (e.g. from a WLAN) are blacklisted

automatically by the network manager and will be avoided

Elements of WirelessHART - TDMA

• Time Division Multiple Access (TDMA)– All WirelessHART participants are highly accurate synchronized – The synchronization of all participants is managed by the network

manager in a master frame– They start to communicate within a 10ms time frame– Between the communications, the participants go into sleep mode to

save Battery Power. The adaptor though is always transmitting connected to the wireless network…the adaptor works as a repeater


Time

WLAN Channels

10ms 20ms 30ms 40ms 50ms 60ms 70ms

1

2

3

4

15

16

:

Blacklisted


• Results in terms of throughput, covered area as well as reliability– Reliability is increased through redundant paths– Range and Area is increased through routing

≤ 200m between two access points (best case)– Throughput is maximized with 16 Channels x 100 slots = 1600

Communications per second within the whole Network– Usable net throughput: 30% (480 signals per second), rest is for

resending messages and overhead

Mesh Network: How it Works

Wireless Network

Before the actual operation, several other issues must be addressedfirst to add a new device to an existing network and/or to create andinstall a new devices to a new network• Identifying Networks and the associated devices• Forming Networks • Secure the Network

Elements of WirelessHART – Network ID

Network Identification• Each Network is identified by a unique Network ID• Each Device in this Network must carry this Network ID for

identification• This enables also to run a second WirelessHART Network in

parallel with another Network ID

How to form a Network

To form a Network, following steps must be taken• Set Network ID and Join Key in the Network Manager (NM) • Set same Network ID and Join Key in the field device that shall

be added to the network• For security reasons, both Network ID and security ID must be

set in the devices with a wired interface (either HART FSK or RS485)

• When switching the field device on, it will ask the NM to join the network

• If Network ID and Join Key are OK, it will be added to the network, otherwise joining will be refused

Network ID / Join Key: How it Works

Set NW IDSet Join Key

Want to Join withNW ID and Join Key

NW ID and Join Key OK,new device accepted

WirelessHART and Safety

• To make communication safe, all messages are encrypted with a 128Bit encryption key

• The encryption keys are distributed and changed in certain intervals by the Network Manager

• This makes it very hard to break into a WirelessHART Network. The “hacker” would need to…

– find out Network ID– find out Join Key– find out encryption key

• The only way for a “hacker” to find this information would be during the join-up phase!

• For security reasons, both Network ID and security ID must be set in the devices with a wired interface (either HART FSK or RS485)

• Therefore the WirelessHART infrastructure is very safe!

HART Field Device Functionalities – Part I of II

• Field devices could be– Externally powered (via 4to20 mA signal)– Solar powered– Battery powered

• At the moment the expected battery life time is approx. up to 5 years– Depending on Duty cycle

• WirelessHART is downward compatible with existing HART devices and applications– e.g., control systems, PLCs, maintenance tools, and asset management

applications can utilize WirelessHART with minor software upgrades (new DLL, new DDs, new DTMs).

HART Field Device Functionalities – Part II of II

• Field devices can be configured by means of– Notebook using FDT compliant PACTware, DTM and a HART

modem– Handheld Terminal 375/475. Ensure the DD-files for the WH

Adaptor are loaded

Questions and Answers

• Is the antenna of a WirelessHART device always transmitting– Yes, the antenna is always transmitting as long as the battery is

installed. Therefore it is very important to remove the battery when the unit is not in use and stored or transported

– The adaptor also works as a repeater, therefore the battery must be installed and the unit must be on

• Will the adaptor affect the Ex-values if connected to a field-device?– The adaptor does not influence the Ex values of the field device since

both units are energetically decoupled and treated independently, similar to the fact if you add the Handheld terminal to the field device. The adaptor just “picks up” the HART communication. This is why the adaptor always comes with a battery

• What about loop powered adaptors – Loop powered adaptors w/o batteries will be available in the future. The

design is more complex, since this might interfere with Ex related values of the field device.

Questions and Answers

• Can a WirelessHART adaptor HART enable a pure 4 to 20 mA device– No, the WirelessHART adaptor is just like a HART modem or a Handheld.

The adapter only accesses the data from the conventional field device via HART. The adaptor therefore can only “pick up” the HART information from the field device, but cannot convert an analog PV into HART

• How many IOs does a WirelessHART gateway and adaptor support?– The WirelessHART gateway can support up to 1,000 IOs. The

WirelessHART adaptor can connect up to 4 IOs• Where can I achieve savings from WirelessHART?

– Mainly for incremental and temporary measurements e.g. for condition monitoring

– Field Devices can be added without the need for installation of cable ducts or field-wiring

– Retrofit of HART communication to existing conventional installations without replacing the communication module (FBM) installation

– A gateway supporting up to 1000 IOs needs to be seen as a replacement to communication modules

New Connectivity to existing Devices

Retrofitting Application for existing infrastructures that do not support HART communication today

Wireless Devices for Measurement & Control

Adding field devices to a new or existing infrastructures that would require expensive wiring.

Application Examples

Environmental monitoring: Environmental monitoring: CorrosionCorrosion

CorrTran MV


Storage: Storage: Continuous Level MeasurementContinuous Level Measurement


Storage: Storage: Discrete Level MeasurementDiscrete Level Measurement


Monitoring: Monitoring: Valve Lever PositioningValve Lever Positioning


Monitoring: Monitoring: TemperatureTemperature

2 channelWirelessHARTTemperatureMultiplexer

PROTECTING YOUR PROCESS

karsten fischer - p+f wirelesshart demo & applications i · • wirelesshart is downward...

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