Introduction The purpose of this tutorial is to demonstrate the Modbus Master communication functions of the i . Modbus has been an industry standard for many years with more and more devices being Modbus enabled. Thus almost any device from Pressure transducers, to remote I/O and inverter drives can be controlled by an i In this tutorial we will demonstrate the i as a Modbus master, controlling a network...
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The Modbus master protocol utilises the Modbus function codes 03 to read single and multiple registers, 10 to write to multiple registers and 06 to write to single registers. Most Modbus slave devices only use the function codes 03 to read and 06 to write. Therefore the i can communicate with any Modbus enabled device.
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Select the Modbus device register address and the length of the data The data in the device address will be stored in the i locally where specified in a particular register The type command and update type are define here. Whether the data is read or write and polled always or triggered on a bit.
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Next we have to enter the logic to control the fan for the reading of the temperature controller. If the Present Value is greater than the Set Point then we need the fan to switch on. Select the Greater than icon from the Compare functions menu and insert it in a rung with a N/O contact assigned to “always on”.
Screen 3 The third and last screen will display the communication status of the two devices as set up in the protocol config. Place two numeric data functions on the screen and one screen jump function two go back to the first screen. Assign one numeric function to the temperature controller status and the second to the drive status, both will be none editable.
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