Do you want to control multiple inverter drives at the same time?
Traditionally, you would assign an analogue output from the PLC to control the speed of each drive and then use digital relays to start and stop them.
The problem with this method is that using a 0-10v analogue signal over long distances will cause voltage drop and the amount of I/O points used will quickly add up, especially if you want real time feedback from the drive.
This could potentially be a wiring nightmare, but using the Unitornics PLC and inverter drives we can make life a lot easier.
However, using Modbus and some very simple function blocks in your ladder logic, all you need is one Modbus cable and you can daisy chain the drives together. This will give you control and feedback with no IO required.
In UniLogic, you specify the drive you’re using, set the modbus ID and then set configuration parameters such as acceleration and deceleration.
Then you can add some functions to start the drive at the direction and speed required as well as stopping the drive or jogging the drive momentarily. This set up will also give you fault readings as they occur for fast diagnostics giving you access to all the drive parameters. You’re then able to link these ladder functions to variables on the screen or other functions in your code and there you have it! You can control multiple VFDs simultaneously, starting the drives, changing the configurations, controlling the speed and all with real time data fed back to the PLC for useful parameters such as current speed, voltage, amperage and fault codes.