What are the steps to interface a VFD with a PLC?
To connect a VFD to a PLC, you typically follow these steps:
Step-1: Wire the power connections: Screw the 3-phase AC supply cable on to the VFD and the motor supply terminals of the VFD.
Step-2: Connect the control signals: Plug in other input signals which include start/stop, forward/reverse for the use of the VFD through the digital inputs of the PLC. Analog signals can also be employed in speed regulation or contain certain speed information.
Step-3: Set up communication: If possible integrate, the VFD with the PLC through the serial communication port of the VFD (for instance RS-485, Modbus, Profibus etc). Set up the Communication parameters of both the devices.
Step-4: Program the PLC: A program in the PLC has to be developed in order to control the VFD. Choose the proper instructions and the data types with respect to the communication technique. Co-ordinate the control and status data of PLC to VFD.
Step-5: Configure the VFD: Once again, set various parameters in the VFD including the motor rating and control mode, interaction between VFD and the PLC as well as any other requirement in the application.
Step-6: Test the integration: Check the proper functioning of the VFD-PLC system by controlling different options connected with the motor, as well as the statuses describing its condition.
The step-by-step details of the wiring, programming, and configuration may differ according to the type of the PLC and VFD involved, but typically they are not greatly dissimilar. For specific connection procedures of your existing PLC and VFD brands, kindly consult the enclosed users manuals.