Connecting UniOP to Modbus/TCP

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Tech-noteFigure 1 - Controller Setup dialog boxThe IP address identifies the Modbus/TCP device on the network. The Unit Identifier is rarely usedand in most cases can be left zero. The value of the Unit Identifier is simply copied into the UnitIdentifier field of the Modbus/TCP communication frame. Usually it is used when communicatingover Ethernet-to-Serial bridges and is then representing the Slave ID.The “Disable Modicon Mode” checkbox allows specifying whenever the addressing mode shouldfollow the original Modicon standard, or a more general approach where the address for the variablesstarts from index zero.If Modicon Mode is enabled, the legal range for each data type is: 1...65536.If Modicon Mode is disabled, the legal range for each data type is: 0...65535.Please note that the permissible addressing range does not mean that the controller connected to thepanel is actually containing that amount of variables.One of two PLC models can be chosen. Selecting the “Generic ModbusTCP” PLC model will indicateto UniOP that it is allowed to access multiple data items at once resulting in greater display refreshratio. Selecting the “Generic ModbusTCP - no data blocks” will force the UniOP to access single dataitem only per communication session. This will, of course, slow down the display refresh ratio, butcan be useful when communicating to devices that have only basic Modbus functionalityimplemented. Check appendix B for more details.The “Time-out” parameter defines the time inserted by the protocol between two retries of the samemessage. It is expressed in milliseconds.The “Port” parameter allows to change the default port number used by the Modbus TCP driver; itcould be useful whenever the communication passes through Routers or Internet gateways where thedefault port number is already in use.Two radio buttons are available to specify what Modbus Function will be used for write operations tothe Holding Registers data type. The user can select between the function 06 (preset single register)and function 16 (preset multiple registers).If the Modbus function 06 is selected, the protocol will always use function 06 to write to thecontroller, even to write multiple consecutive registers.tn165-5.doc - 8.06.2005Connecting UniOP to Modbus/TCP 4
Tech-noteIf the Modbus function 16 is selected, the protocol will always use function 16 to write to thecontroller, even for a single register write request and the “Byte Count” parameter of the query is setto two. Using function 16 may result in higher communication performanceBy default the Modbus Function 16 is used and should be disabled only for those controller that to dotsupport it.The protocol allows the connection to multiple Modbus/TCP devices connected to one UniOP panel.In that case, the “Access Multiple Drives” option has to be used. The dialog box will change and willappear as shown below in Figure 2.Figure 2 - Controller Setup Dialog Box for multiple controllersBy Pressing down the “Add” button you may add new Modbus/TCP devices to the network and entertheir IP address. UniOP can communicate with several Modbus/TCP devices.3.2 Panel SetupThe operator panel must have an IP address to connect to Ethernet.The IP address of the panel must be entered in Panel Setup dialog box in the tab “External Devices”.Enter the IP address in the “Ethernet board” field as shown in Figure 3 below.tn165-5.doc - 8.06.2005Connecting UniOP to Modbus/TCP 5
Page 3: Tech-note1 IntroductionThe Modbus/T
Page 7 and 8: Tech-note2. Convert the project to
Page 9 and 10: Tech-noteAppendix B. Implementation

Connecting UniOP to Modbus/TCP

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