Integrated PLC enables inverter to control machine and other drives
Designed for unparalleled drive precision, speed control, simple start-up, and versatility, Mitsubishi Electric’s FR-A800 inverter drive series is equipped with a high-speed processor designed to control an entire machine, not only the drive’s operation.
The PLC function provides improved control and response levels across a range of applications, offering the control sequence best suited for the machine specifications. It is programmed using Mitsubishi’s standard PLC software, available in FR Configurator2. It is also possible to combine the PLC program with the real-time clock of the drives’ operation panel.
Local or decentralised control
Inverter operation sequence can be customised for the machine. A set of operations (operation at different signal inputs, signal and monitor outputs at different inverter status, etc.) can be programmed in accordance with the machine specifications. For example, a shutter opening/closing can be performed based on a signal from a sensor, or based on the opening/closing times.
In decentralised control, the control of the whole system is decentralised to inverters that mange their subordinating devices individually. A group of dedicated sequence programs is created and saved in each inverter. The master controller no longer has to process all the sequence programs, and the decentralized system accepts program changes more flexibly.
Up to 50 user parameters linked with the data registers, can be saved. The variables used in the PLC function can be saved as inverter parameters. If required, the parameter settings can be saved in the EEPROM of inverter. When results of calculation using the PLC function are saved in the parameters, the data can be retained after the power is turned OFF.
FR-A800 offers machine builders many other useful functions, including:
|– PID operation||– Two different loops of PID inverter operations can be pre-set, and those can be controlled using sequence programs.|
|– User initiated fault||– Inverter output can be shut off under conditions other than those of the existing protective functions.|
|– Inverter operation lock||– The inverter operation can be restricted to the PLC. Changes to settings caused by operator error can be avoided.|
|– Monitored item for the user||– Desired data is displayable on the operation panel.|
Typical machine control applications include:
The travelled distance (total number of travel pulses) of each wheel is directly read from the encoder installed at the wheel. The pulses from the two wheels are then compared, and their speed is adjusted to synchronize the wheel positions. There is no need to use an external controller to offset speed, allowing high accuracy control.
The workpiece positions detected by sensors are directly reported to the inverter, and the inverter sends out the operation commands to the conveyor robot and to the extruding machine. Whole control can be performed by an inverter, in accordance with the movement of its peripheral equipment.
Signals sent via the enclosure (relay panel, etc.) such as input magnetic contactor signals, watt hour meter signals, and sensor signals can be read directly into the inverter and controlled. A fan can be controlled in accordance with the conditions without using relays.
By using an external 24 VDC power source for the control power supply, input machine signals can be turned ON and OFF regardless of whether there is an input power source. And by employing an external 24 VDC power supply for the control power, input machine signals can be turned ON and OFF, regardless of the existence of a main circuit power supply.
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