THE PEPPERL+FUCHS GROUPWirelessHART Demo & Application Overview
Karsten Fischer - Global Account Manager Invensys
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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
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Elements of WirelessHART
WiredInterface
WirelessHARTNetwork
WH-Gateway-Network Manager-Network Access Point
WH-Adaptor
Field-Device
Wireless Transmission
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Elements of WirelessHART
• 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
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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
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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.
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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
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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
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Elements of WirelessHART
Time
WLAN Channels
10ms 20ms 30ms 40ms 50ms 60ms 70ms
1
2
3
4
15
16
:
Blacklisted
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Elements of WirelessHART
• 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
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Mesh Network: How it Works
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Mesh Network: How it Works
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Mesh Network: How it Works
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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
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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
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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
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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
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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!
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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).
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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
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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.
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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
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New Connectivity to existing Devices
Retrofitting Application for existing infrastructures that do not support HART communication today
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Wireless Devices for Measurement & Control
Adding field devices to a new or existing infrastructures that would require expensive wiring.
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Application Examples
Environmental monitoring: Environmental monitoring: CorrosionCorrosion
CorrTran MV
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Application Examples
Storage: Storage: Continuous Level MeasurementContinuous Level Measurement
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Application Examples
Storage: Storage: Discrete Level MeasurementDiscrete Level Measurement
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Application Examples
Monitoring: Monitoring: Valve Lever PositioningValve Lever Positioning
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Application Examples
Monitoring: Monitoring: TemperatureTemperature
2 channelWirelessHARTTemperatureMultiplexer
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PROTECTING YOUR PROCESS