Connecting Modbus and LonWorks Networks - FieldServer ...

Connecting Modbus andLonWorks NetworksPresented by:Gordon MacLachlan (Mac)

Presentation Highlights‣Properties of a Modbus Network• Data Types and formats• Data Transfer methodologies‣Properties of a LonWorks Network• Data Types and formats• Data Transfer methodologies‣Matching up the networks: Dealing with the challenges• Data Resolution• Engineering Units• Simple vs Structured variables• Single vs Block Data Transfer• Master/Slave vs Peer/Peer communications• Multiple vs single node representation• LonMark vs Modbus-IDA‣Resources‣Questions and Answers

The Modbus Standard‣ A truly open standard.‣ Based on Master/Slave poll and responsetopology.‣ An integer protocol, i.e: : floating point is notsupported by the protocol‣ Supports 4 basic data types:‣ Analog Inputs‣ Analog Outputs (Registers)‣ Digital Inputs‣ Digital Outputs (Coils/Flags)‣ Supports 65535 addresses per data type‣ Builds NO intelligence into what it is sending, i.e:it does not care what the data in the registersrepresent.‣ Worldwide use as the most supported protocol.

AddressFormat 1(Modicon style)000 001065 536100 001165 536Modbus Memory MapData TypeFlags (Read/Write)Digital Inputs (Read Only)Offsets in each data type:0-65535Read: Function Code 1,AddressFormat 2(PDU Addressing)Write Single: Use Function Code 5Write Multiple: Use function Code 15Read: Function Code 2,Write Single: N/AWrite Multiple: N/A300 001365 536400 001465 536Analog Inputs (Read Only)Registers (Read/Write)Read: Function Code 4Write Single: N/AWrite Multiple: N/ARead: Function Code 3Write Single: Use Function Code 6Write Multiple: Use function Code 16

0000165536Modbus Memory MapAddressFormat 3ADU AddressingData TypeFlags (Read/Write)New in 2004 modbusspec.AddressFormat 2(PDU Addressing)Read: Function Code 1, Offsets 0-9998Write Single: Use Function Code 5Write Multiple: Use function Code 1500001655360000165536Digital Inputs (Read Only)Analog Inputs (Read Only)Read: Function Code 2, Offsets 0-9998Write Single: N/AWrite Multiple: N/ARead: Function Code 4, Offsets 0-9998Write Single: N/AWrite Multiple: N/A0000165536Specify Data type& address forcomplete address.Registers (Read/Write)Read: Function Code 3, Offsets 0-9998Write Single: Use Function Code 6Write Multiple: Use function Code 16

Modbus VariationsVariations due to difference in connectionmedium:‣ Modbus RTU: : Most common Modbus variation.Communication medium is RS-232 or RS-485. Datatransferred in hexadecimal format. Only one masterallowed.‣ Modbus ASCII: : Uses RS-232 or RS-485. Data istransferred in ASCII format. Only one masterallowed.‣ Modbus TCP: : Ethernet. Data transferred inhexadecimal format using the TCP/IP transportprotocol. Allows multiple masters‣ Modbus Plus: : Uses a proprietary medium. Specialhardware needed. Allows multiple masters.‣ All of the above protocols support Modbus in its trueformat.

Modbus VariationsVariations resulting from protocol restrictions:The following FieldServer drivers are Modbus variants:Modbus TekairModbus DanielsModbus OmniFlowThe manufacturer compensated for Modbus being a16 bit integer protocol by providing a method forsending 32 bit values. Many other vendors do thistoo.Additionally, FieldServer has a special move functionthat can assist in decoding these 32 bit variants foruse by other protocols.

Modbus VariationsVariations resulting from protocol restrictions(JBus):‣ JBus is no different from extended Modbus, withlegal data type addressing from 1-655351

Modbus TCPDealing with Ethernet and Modbus TCP:‣ User needs to understand subnetting and IPaddressing‣ Using Modbus TCP across subnets requires theuse of IP gateways. . Gateway address setting inIP configuration becomes important‣ Modbus TCP uses port 502 to communicate.Important if punching a hole in any firewall forcommunications.‣ Modbus TCP uses TCP/IP connectionmanagement to allow multiple communicationsconnections making multiple masters on aModbus TCP Network possible.

Modbus TCP –Troubleshooting onEthernet‣ Use a good Ethernet capture tool such as Ethereal(free at www.ethereal.com)‣ For testing, , Modscan32 or similar is recommended(www.win-tech.com). Use to emulate a Client on thenetwork and test communications.‣ Know the network layout, , including all subnets,Modbus TCP devices, routers, and firewalls whichcan influence communications. A detailed networklayout diagram is essential.‣ IP Addressing – does your device‣ Support IP addressing in conjunction with variable Unitidentifier (Node_ID(Node_ID)?‣ Fix the unit identifier and work with IP addressing only?‣ Know which variant involved - FieldServer will need to fix itsNode_ID to the correct address if the latter is in use.

LonWorks OverviewLonWorks Addressing‣ DSN – Domain, Subnet, Node‣ Typically, the Network Manager assigns the domainaddress for a network, following which the required subnetsfor a domain are determined by routers needed in thesystem. Node addresses on each subnet are then allocatedby the Network Manager.‣ The LNS report utility prints out all DSN addresses for aDomain.

LonWorks OverviewNetwork Managers‣ LonMaker, LonWatcher, , and others…‣ Traditional LonWorks setup requires a network manager‣ Network manager “binds” data points together, and canthen be removed.

LonWorks OverviewNetwork Managers‣ Network Managers allocate addressing on the network‣ A LonWorks network can be commissioned without aNetwork Manager, but this requires more advancedtechniques.

LonWorks OverviewNetwork Variable Types‣ SNVT – Standard Network VariableType‣ UNVT – User Network Variable Type‣ SCPT – Standard ConfigurationParameter Type‣ UCPT – User ConfigurationParameter Type

LonWorks OverviewData Transfer – Update vs Polled‣ Update variables send datato a remote device using anevent driven mechanism‣ Event driven mechanismsinclude: Continuous update,Update on change, andThrottling mode‣ Polled variables wait to bequeried for data, and thenrespond when queried.‣ Typically, polled variablesoperate on a continuousupdate methodology

LonWorks OverviewXIF filesFile generated by TAC Menta version 4.0, XIF Version 3Copyright (c) 2002 by TAC ABAll Rights Reserved.Run on 2004-06-08 15:4980:00:13:52:00:06:04:6E2 15 1 31 2 5 2 0 0 2 6 11 13 13 11 3 0 1611 5 9 13 28 0 0 15 5 3 1131 7 1 0 4 4 4 15 200 078125 0 0 0 0 0 0 0 0 0 0 090 0 240 0 0 0 40 40 0 5 8 5 12 14 15*"&3.0@0,5VAR SNVT_ObjReq 0 0 0 00 1 63 0 0 0 0 0 0 0 0 0 0"@0|192 * 22 0 0 0 01 0 0 1 0VAR SNVT_ObjState 1 0 0 00 1 63 1 0 0 0 0 0 0 0 0 0"@0|293 * 262 0 0 0 03 0 1 0 0Program_IDSNVT_IDSNVT_Type‣ XIF (externalinterface) files containinformation about thevariables on a device,and all the necessaryvariable properties.‣ XIF files go a long wayto providing all theinformation neededfor FieldServerconfiguration, but donot contain DSNinformation.

LonWorks OverviewNeuron ID’s vs Program ID’s‣ Neuron ID - Uniquely defines the Neuron chip onthe network. No two Neuron chips in the worldhave the same ID.‣ Program ID - defines an application on ahardware platform, and is possible for twohardware platforms to have the same Program IDbecause they are running the same application.‣ If an application changes, then its Program ID mustchange too. This means when Lon variables are modifiedin the FieldServer configuration, the Program ID mustchange.‣ If the Program ID changes for a device, then that deviceneeds to be removed from a network, and thenrecommissioned.‣ The Lesson to be learned: Plan your variable listcarefully before commencing with binding.

Sustainability 40/40 20/21SUSTAINABLE THINKINGENERGY EFFICIENCY IS BUILT INTOTHE FABRIC OF 10–4 PENTONVILLEROAD. INNOVATIVE LIGHTINGAND HEATING SYSTEMS PROMISECONTROLLED ENERGY USE, FEWERCARBON EMISSIONS AND REDUCEDRUNNING COSTS.HEAT RECOVERYThe building is equipped with a variable refrigerant flow (VRF)simultaneous heating and cooling system for a high level ofenergy efficiency. For comparison, the carbon emissions of aconventional chiller and boiler combination would typicallybe 10-20% higher.Each internal AC unit can be operated individually via a dedicatedcontroller or temperature sensor, enabling the system to recover and reuseexcess heat. For example, the AC unit in a densely-occupied meetingroom will be in cooling mode even if units elsewhere are heating, sothe system ensures the residual heat from the first unit is recovered toprovide free heat for the others. The same principle applies betweenunits on the building’s north- and south-facing façades.In a similar way, the fresh air ventilation systemuses energy efficient heat recuperators to recoverthe residual heat from extracted air to heat theincoming fresh air.INTELLIGENT LIGHTING10–4 Pentonville Road incorporates an intelligent lightingcontrol system able to adapt to changing levels of occupancyand daylight to maximise energy savings. Each floor of thebuilding has its own control unit so that tenants can modifythe lighting settings to meet their individual requirements.The whole system is PC-based for easyreconfiguration, and all lights have beencarefully chosen to ensure overall lampefficacy exceeds 45 lumens per circuit watt.ADDITIONAL SUSTAINABLE FEATURES—Targeting BREEAM Very Good—High-performance solar-control glazing to minimiseheat gains, and thus reduce cooling load—Upgraded thermal insulation to reduce heat loss—Low water-use sanitary fittings—Solar hot water heating

LonWorks ConfigurationBasic Configuration File (Connection Information):Define Connection and Node://================================================================================// LonWorks ConnectionConnectionsAdapterLonworksProtocolLonworks//================================================================================// LonWorks NodeNodesNode_NameEC001ProtocolLonworks

LonWorks ConfigurationBasic Configuration File (Mapping):Define SNVT’s s (Map them to the Data Array)://================================================================================// LonWorks Map DescriptorsMap_DescriptorsMap_Descriptor_NameData_Array_NameData_Array_Offset Lon_Function FunctionNode_NameSNVT_TypenviSpaceTmp DA_Temps 0 NVUI Server EC001 SNVT_temp_pnvoSpaceTmp DA_Temps 1 NVUOIMX wrbx EC001 SNVT_temp_p

Lonworks ConfigurationXIF for Basic Configuration File :fserver.xif:File: fserver-2.xif generated by LonDriver Revision 1.20(g), XIF Version 4.0Copyright (c) 2000-2004 by FieldServer TechnologiesAll Rights Reserved. Run on Tue Jul 26 07:58:26 200580:00:95:47:1E:02:04:362 15 1 2 0 14 11 3 3 12 14 11 11 11 11 3 0 16 63 0 1 11 20 5 7 13 28 0 0 15 5 3 109 631 7 1 0 4 4 4 15 200 078125 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 1 5 8 5 12 14 15*"EC001 FieldServer v1.00aVAR nviSpaceTmp 0 0 0 00 1 63 0 0 0 0 0 0 0 0 0 0*105 * 12 0 0 1 0VAR nvoSpaceTmp 1 0 0 00 1 63 1 0 0 0 0 0 0 0 0 0*105 * 12 0 0 1 0

Lonworks ConfigurationCommissioning EC001 into LonMaker :Step 1: Load config into FieldServer and reboot FieldServerStep 2: Open a project in LonMakerStep 3: Drag device into Visio drawing.Step 4: Complete the device commissioning wizard.

Lonworks ConfigurationCommissioning EC001 into LonMaker :Step 5: Press the Service Pin on the FieldServer, wait for EC001 tocommission.Step 6: Drag a Function Block into Visio

Lonworks ConfigurationCommissioning EC001 into LonMaker :The end result: You are now ready to bind to other devices using the“Connector” Tool.

Translation ChallengesData ResolutionTHE CHALLENGE‣ LonWorks‣ Supports data types from 8-bit 8through to 64-bit and allowsfor corresponding resolutions in the different SNVT’s‣ LonWorks has two common SNVT’s s to manage binary datatransfer: SNVT_switch and SNVT_state. . Both are 16-bitSNVT’s.SNVT_switch is more popular.‣ Modbus‣ Supports two basic data types: 1-bit 1and 16-bit.‣ All Modbus variations that support 32-bit are applicationlayer enhancements that combine two registers at the lowerlevel‣ The challenge is matching the different resolutions in thetwo protocols to achieve the desired resolution for theapplication.

Translation ChallengesData ResolutionTHE SOLUTIONS‣ Use FieldServer’s s Scaling functions to scalevalues if this provides enough resolution‣ Use FieldServer’s s 16 to 32 bit move functions tocreate 32 bit values for perfect 32 bit resolution‣ Use FieldServer’s SNVT_Option feature inLonWorks to match a binary modbus value withthe state portion of SNVT_switch

Data ResolutionSNVT_Option Feature//================================================================================// Temperature Mapping in Deg_FMap_DescriptorsMap_Descriptor_NameData_Array_NameData_Array_OffsetLon_FunctionFunctionNode_Name SNVT_Type SNVT_UnitsnviSpaceTmp DA_Temps 0 NVUI Server EC001 SNVT_temp_p Deg_FnvoSpaceTmp DA_Temps 1 NVUOIMX wrbx EC001 SNVT_temp_p Deg_FScale Fahrenheit to Celsiusby telling the driver that theData Array value is Deg_F‣ All SNVT’s s include required scaling in their definition.‣ The FieldServer automatically scales the raw data according tothe SNVT scaling rules. Value in Data Array is the scaled value.‣ Note that LonWorks is inherently METRIC. Thus, non-metricapplications still require extra parameters in the configuration(SNVT_Unitsfield)

Data ResolutionTypecastingModbus and Typecasting (FieldServer does this bydefault)‣ Each protocol variable type is allocated a default Data type‣ Moves between dissimilar data types result in type-casting‣ To avoid type-casting, use matching data array types or specialfunctions such as Floating point moves or Packed Bit Data ArraysExample variable typesModbus 3xxxxDefault Type = Uint16Modbus 1xxxxDefault Type = BitPollChange valueto a floatingpoint valueFloat DataArrayChange value to aunsigned integervalueUint16 DataArrayChange valueto a bit valueBit DataArray

Data ResolutionScalingManaging Floating point values with Integers -ScalingMap_DescriptorsNode_Name ,Address ,Length ,Data_Array_Low_Scale ,Data_Array _High_Scale ,Node_Low_Scale,Node_High_ScaleMBP_Srv_1 ,30001 ,200 , 0 ,10 ,0 ,100Data Array-------------------------Offset 0: 26.4-------------------------Offset 1: 32.5-------------------------X10Remote Device-------------------------Offset 0: 264-------------------------Offset 1: 325-------------------------

Data ResolutionFloating Point MovesSupporting 32 bit values with Modbus‣ FieldServer concept for manipulating “modbusfloating point”(Concept is the same for 32 bit integers):MovesSource_Data_Array ,Source_Offset ,Target_Data_Array ,Target_Offset ,Length ,FunctionSource_DA ,0 ,Target_DA ,40 ,10 ,2.i16-1.float-swModbusDeviceTwo 16 bitintegers polled:e.g: 40001,length 2Together, theycombine toform a 32 bitIEEE Floatingpoint number.Modbus PollSource DataArray-------------------------Offset 0: 40001-------------------------Offset 1: 40002-------------------------SpecialMoveUnreadablecontentFloat DataArray-------------------------Offset 40: Float value-------------------------Sensible data.Map toSNVT_count_for similar

Data ResolutionBit Packing//================================================================================//// Data Arrays// Packed_Bit is enabled merely by declaring the data array to be// of type: Packed_BitData_ArraysData_Array_Name ,Data_Format ,Data_Array_LengthPacker ,Packed_Bit ,200Packed Bit Data ArrayModbus 3xxxxDefault Type = Uint16PollNo typecastingoccurs. Data Arrayis treated as typeUint16 to Matchvariable typeOffset 030001Offset 0DI 1….DI16------------------------------Offset 130002Offset 16DI17…DI32No typecastingoccurs. Data Array istreated as type Bit tomatch variable typeMove each bit to a bitdata type

Translation ChallengesEngineering UnitsTHE CHALLENGE‣ Modbus is a simple protocol that transfers raw data andapplies no significance to any of the values transferred.‣ Significance is achieved through documentation of theModbus registers in the vendor documentation‣ LonWorks is obsessive about applying significance tovalues transferred. All SNVT Types inherently possess anEngineering unit, data resolution and data range.‣ All Engineering units in LonWorks are SI (Metric). This isnot obvious to most LonWorks users as applications suchas LonMaker will automatically scale the values to Imperialformat in the USA.‣ The challenge is matching up the values’ Engineering unitsused in Modbus with the SI Engineering Unit specified inLonWorks

Translation ChallengesEngineering UnitsTHE SOLUTIONS‣ Use FieldServer’s s Scaling functions to scalevalues where data ranges differ.‣ Use FieldServer’s SNVT_Units feature inLonWorks to tell the LonWorks driver whetherthe data array value is represented as Imperialor SI.

Translation ChallengesSimple vs Structured VariablesTHE CHALLENGE‣ All Modbus variable types possess a simple structure.‣ This essentially means that one Modbus variablerepresents one value. The exception is when vendorsuse a register to represent 16 binary states.‣ LonWorks consists of a combination of SNVT’s s thathave both simple structures and “Structuredvariables”.‣ Structured variable consists of a variable thatrepresents multiple values, i.e. SNVT_Switch consistsof two values, the state portion representing a binaryvalue, and the value portion representing a percentage.Both are transferred as part of one variable.‣ The challenge is to group data from Modbus thatneeds to be sent as a structured variable inLonWorks, or to split structured variables fromLonWorks into simple Modbus variables.

Translation ChallengesSimple vs Structured VariablesTHE SOLUTIONS‣ Use FieldServer’s Packed_Bit arrays to split modbusregisters representing 16 binary values into 16separate separate variables OR‣ Represent the Modbus registers representing 16binary values as SNVT_state in LonWorks. It is aperfect match.‣ Use FieldServer’s SNVT_Option feature in LonWorksto match parts of a structured variable up withindividual values from Modbus‣ Use FieldServer’s s move function to group data thathas to be represented as a structured SNVT.

Simple vs Structured VariablesStructured Variables//Structured SNVTMap_DescriptorsMap_Descriptor_NameData_Array_NameData_Array_OffsetFunctionNode_NameLon_FunctionSNVT_IndexSNVT_TypenvoRhEnableDA_AO_01 1 rdbcLon_01NMFETCHC 9 SNVT_switchnvoUnOccRhDA_AO_01 3 rdbcLon_01NMFETCHC 10 SNVT_lev_percentAllow for 2 pointsin the Data Array‣ Structured Variable Types pack more than one variableinto the variable type‣ SNVT_switch, , for example, has two variables associatedwith it: Value (0-100) and state (0/1).‣ The FieldServer can extract all variables from a structuredtype. Some are easy to work with, others are not.‣ Note: while extracting ASCII characters out of a structuredSNVT is possible, it does not make much sense in the“Gateway” model due to limitations of other protocols likeModbus.

Simple vs Structured VariablesSelective transfer of Structured Variables//================================================================================// Temperature Mapping in Deg_FMap_DescriptorsMap_Descriptor_NameData_Array_NameData_Array_Offset Lon_Function Function Node_Name SNVT_Type SNVT_OptionnviAlarm_1 DA_Binary_State 0 NVUI Server EC001 SNVT_switch StatenvoAck_1 DA_Binary_State 1 NVUOIMX wrbx EC001 SNVT_switch StateLoad only thevalue needed‣ When working with a Structured Variable, FieldServerallows you to fetch just the portion of the structuredvariable needed by declaring the SNVT_Option field.

Translation ChallengesSingle vs Block Data TransferTHE CHALLENGE‣ LonWorks sends and receives data one variable at atime.‣ Modbus works most efficiently when data istransferred in blocks. That is: each poll for datareturns many values.‣ The challenge is to keep both networks efficient bygrouping data together for block transfer on theModbus side.

Translation ChallengesSingle vs Block Data TransferTHE SOLUTIONS‣ Use FieldServer’s s move functions to group dataneeded for a block transfer into one data array.‣ Plan the data blocks so that one poll contains nomore than one object/device. Thus, the absence ofone device does not prevent the transfer of datafrom a working device from going through.‣ Don’t t be scared of “empty” data array offsets if ithelps to structure a block for simple Modbusmapping.‣ Serve the block up to Modbus using one mapdescriptor only.

Single vs Block Data TransferModbus as a slave – Keep data map “large”contiguous‣ Why? Because you don’t t know how a client will structure itspoll, and if it polls for undefined points, the poll will fail.Lon Variable 1Lon Variable 2Lon Variable 3Lon Variable 4MovesServer SideData Array1 ServerData Arraymeans 1Server mapdescriptor ispossibleRemoteClient cannow poll theFieldServerusing largepoll lengthswithout fearof hittingundefinedregisters.

Single vs Block Data TransferHelp! I’m I m getting “could not create cacheblock”‣ This error occurs frequently when the FieldServer is configuredas a modbus slave‣ It means that the FieldServer has received a poll for addressesthat do not exist in the FieldServer under any one Server mapdescriptor.‣ The content of the error message will tell what poll wasreceived. The message can be interpreted as follows:T02> MODBUS_TCP : Could not create cache blockT02> Node:1 Addr:40001 Len:100Server Nodebeing polledModbusAddressbeing polledLength of poll

Single vs Block Data TransferConfiguring Data Moves//================================================================================//// Data Arrays//// Declare Data Arrays for the data to be moved. In the real world example,// the Data Arrays may already be declared.//Data_ArraysData_Array_Name ,Data_Format ,Data_Array_LengthSource_DA ,Float ,200Target_DA ,Float ,200//================================================================================//// Set up the moves to move the data.//MovesSource_Data_Array ,Source_Offset ,Target_Data_Array ,Target_Offset ,Length ,FunctionSource_DA ,0 ,Target_DA ,40 ,20 ,Move_Only

Translation ChallengesMaster/Slave vs Peer/Peer CommunicationsTHE CHALLENGE‣ Modbus uses Master/Slave Communication model.‣ Master on the network will request data from all the slaves, andwrite values to the slaves. Slaves merely respond tocommunications from the master and do not initiatecommunications at any time.‣ LonWorks (traditional implicit update messaging) uses a peerto peer model where the outputs in one device will write tothe inputs of another device.‣ The communications is initiated by the outputs and the inputsare essentially passive.‣ The challenge is to match the LonWorks peer to peer modelwith either a Master or a Slave on the Modbus side in such away that the communications behavior is as expected.

Translation ChallengesMaster/Slave vs Peer/Peer CommunicationsTHE SOLUTIONS‣ When the LonWorks interface behaves as a Modbus Slave onthe Modbus side‣ Then LonWorks inputs are treated as Modbus read variables,and LonWorks outputs are treated as Modbus write variables.‣ LonWorks outputs can be set to send when a Modbus writeoccurs (using the NVUOIMX/wrbxcombination), or they can beset to send continuously at a predefined interval(NVUOIMC/wrbccombination)

Translation ChallengesMaster/Slave vs Peer/Peer CommunicationsTHE SOLUTIONS‣ When the LonWorks interface behaves as a Modbus Masteron the Modbus side,‣ Then LonWorks inputs are treated as Modbus write variables,and LonWorks outputs are treated as Modbus read variables.‣ LonWorks outputs can be set to send when a Modbus readoccurs (using the NVUOIMX/wrbxcombination), or they can beset to send continuously at a predefined interval(NVUOIMC/wrbccombination).‣ To achieve the read/write functionality that Modbus provideswith it’s s writes, it will be necessary to provide an out put foreach input on the LonWorks side so that write values can beread back.

Master/Slave vs Peer/Peer CommunicationsData Flow Model – FieldServer is ModbusMasterLonWorksCommandsInputArrayOutputArrayLonWorksStatusModbus ArrayModbus isMaster and pollsthe Modbusnetwork forstatusModbus Poll

Master/Slave vs Peer/Peer CommunicationsData Flow Model – FieldServer is ModbusSlaveModbus PollModbus is Slaveand is polled bythe Modbusnetwork forstatusModbus ArrayInputOutputLonWorksStatusArrayArrayLonWorksCommands

Translation ChallengesMultiple vs Single Node RepresentationTHE CHALLENGE‣ When bringing data from many LonWorks nodes into oneFieldServer, it is possible to represent the FieldServer as asingle slave, OR as multiple slaves in the Modbus network.‣ When bringing data from many Modbus devices into oneFieldServer, it is only possible to represent the FieldServeras one device in LonWorks due to only one neuron beingpresent.‣ Modbus can connect up to 255 devices on a network,depending on physical hardware constraints.‣ LonWorks will only allow one device to bind to up to 15other devices due to address table constraints‣ The challenge is to represent the devices in one network assecurely as possible in the other network, and to allow formore than 15 LonWorks devices to be connected to aFieldServer.

Translation ChallengesMultiple vs Single Node RepresentationTHE SOLUTIONS‣ When multiple Modbus nodes are represented as oneLonWorks node, it is important that the status of theseModbus nodes is known.‣ Use the FieldServer Node Status function for this andtransfer these as a SNVT_States to the network.‣ To bring more than 15 LonWorks nodes into Modbuswith one FieldServer, use the Network Managementfunction in the LonWorks driver (NMFETCHC).‣ The limit for this communication method is restricted onlyby hardware.‣ To bring multiple LonWorks nodes into Modbus, useone Modbus slave address per LonWorks node.‣ A cleaner design prevents offline LonWorks devices frominterfering with working LonWorks devices in the Modbusnetwork.

Multiple vs Single Node RepresentationMonitoring the status of Client side nodes (Servers) – Node Status//======================================================================================//// Notes : All that is needed to enable node status is the node status data array// declaration. Note, though, that Node ID's in the config need to be// unique, otherwise the FieldServer will incorrectly report the status of// duplicate Node ID's////======================================================================================//================================================================================,//// Data Arrays//Data_ArraysData_Array_Name ,Data_Format ,Data_Array_Length ,Data_Array_FunctionDA_Comm_Status ,Bit ,256 ,Node_Status//================================================================================,//// Modbus TCP Server Map Descriptor Turns 10001 into Nde 1 Status, 10002=Node 2, etc.//Map_DescriptorsMap_Descriptor_Name, Data_Array_Name, Data_Array_Offset, Function, Node_Name , Address, Length,Node_Status_Map , DA_Comm_Status , 1 , Server , MBP_Srv_11, 10001 , 200 ,

Multiple vs Single Node RepresentationNetwork Management Messaging‣ A special function intendedfor host systems thatneed to monitor the statusof variables on a network(e.g:: Network Managers)‣ This function uses explicitpolling to obtain theneeded variables.‣ It is possible to write datausing this function too.‣ This function has somevery useful applicationswhen integrating theFieldServer into largernetworks.

Multiple vs Single Node representationNetwork Management Configuration example//=============================================// Common InformationBridgeTitle“:D48:S01:NMManager” 11System_AddressForce FieldServer addressto Domain 48 (hex), Subnet1.Node Address ofthe FieldServer//================================================================================//// Remote NodesNodesNode_name Subnet_ID Node_ID Adapter ProtocolLon_01 1 1 Lonworks LonworksSubnet onwhich theremote deviceresidesNode Address ofthe remotedevice

Multiple vs Single Node RepresentationNetwork Management Configuration Example//================================================================================// NMFETCHC MappingMap_DescriptorsMap_Descriptor_NameData_Array_NameData_Array_Offset Function Node_Name Lon_FunctionSNVT_Index SNVT_Type Scan_IntervalnviClgSP DA_AI_01 0 rdbc Lon_01 NMFETCHC 2 SNVT_temp_p 1.0snviHtgSP DA_AI_01 4 rdbc Lon_01 NMFETCHC 3 SNVT_temp_p 1.0snviRhSP_4 DA_AI_01 13 rdbc Lon_01 NMFETCHC 4 SNVT_lev_percent 1.0sNode_Namerefers to theremote NodeSpecify SNVTIndex of thevariable in theremote device.Scan Interval isspecified withNMFETCHCoperations

Translation ChallengesLonMark vs Modbus-IDATHE CHALLENGE‣ LonMark.org is the organization responsible formaintaining LonWorks standards‣ Modbus-IDA is the organization responsible formaintaining Modbus standards‣ There is no challenge here really, except tounderstand the differences between theobjectives of these organizations

Translation ChallengesLonMark vs Modbus-IDATHE SOLUTIONS‣ LonMark maintains the standards for LonWorks,including such tasks as declaring the official SNVTlist and requirements for Device profiles.‣ LonMark offers testing for device profiles to ensurethat the profiles match the requirements‣ Modbus-IDA maintains the modbus specification.‣ Modbus-IDA offers testing for protocol conformance.‣ ALL open standards organizations like LonMark,Modbus-IDA, ASHRAE etc should be fully supportedby the technical community. It’s s our only way toensure that these protocols remain open.

Resources‣ FieldServer website (www.fieldserver.com(www.fieldserver.com)‣ Modbus-IDA (www.modbus.org(www.modbus.org)‣ LonMark Website (www.LonMark.org(www.LonMark.org)‣ Echelon Website (www.echelon.com(www.echelon.com)‣ Vendor sites (Mapping for Modbus devices)‣ Ethernet packet capture utility (www.ethereal.com(www.ethereal.com)‣ Modscan32 (www.win(www.win-tech.com)

Questions?Marketing and Sales:Steve Ferree: sferree@fieldserver.comTechnical:Mac: mac@sfintegration.com

THANK YOU!…..for taking the time to attendthis presentation.