1. The switch signal of Mitsubishi Plc controls the output point of the Mitsubishi inverter Mitsubishi inverter (MR type or MT type), the COM point directly with the inverter's STF (forward rotation start), RH (high speed), RM (medium speed), Ports such as RL (low speed) and input SG are connected respectively. Mitsubishi PLC can control the start, stop and reset of the inverter through the program; it can also control the different combinations of high-speed, medium-speed and low-speed terminals of the inverter to realize multi-speed operation. However, because it is controlled by the amount of switching, its speed regulation curve is not a continuous smooth curve, nor can it achieve fine speed adjustment. This kind of switching quantity control method can not compare the speed regulation accuracy with the extended memory communication control.
2. Mitsubishi PLC analog signal control inverter hardware: FX1N type, FX2N type PLC host, configure 1 simple FX1N-1DA-BD extended analog output board; or analog input and output hybrid module FX0N-3A; or Two-output FX2N-2DA; or four-output FX2N-4DA module.
Advantages: PLC programming is simple and convenient, the speed regulation curve is smooth and continuous, and the work is stable.
Disadvantages: In large-scale production lines, the control cable is long, especially when the DA module uses voltage signal output, the line has a large voltage drop, which affects the stability and reliability of the system. In addition, from an economic point of view, if you control 8 inverters, you need 2 Mitsubishi plc-FX2N-4DA modules, and the cost is 5 to 7 times that of extended memory communication control.
3. PLC uses RS-485 non-protocol communication method to control Mitsubishi inverter. This is the most commonly used method. PLC adopts RS serial communication command programming.
Advantages: The hardware is simple, the cost is the lowest, and 32 inverters can be controlled.
4. PLC adopts RS-485 Modbus-RTU communication method to control the inverter. The new Mitsubishi F700 series inverter uses RS-485 terminal to communicate with PLC by Modbus-RTU protocol.
Advantages: The plc programming of Modbus communication mode is simpler and more convenient than the RS-485 non-protocol method.
Disadvantages: PLC programming workload is still large.
5. Mitsubishi PLC uses fieldbus mode to control the inverter. Mitsubishi inverter can be equipped with various types of communication options, such as FR-A5NC option for CC-Link fieldbus; FR-A5AP for Profibus DP fieldbus ( A) Option; FR-A5ND option for DeviceNet fieldbus, etc. The FX series Mitsubishi PLC has a corresponding communication interface module to interface with it.
Advantages: Fast speed, long distance, high efficiency, stable operation, simple programming, and a large number of connected inverters.
Disadvantages: The cost is higher, much higher than the cost of using extended memory communication control.
In summary, Mitsubishi PLC's method of using extended memory communication to control the inverter does have the advantages of low cost, easy to learn and use, and reliable performance. If the man-machine interface is configured, the inverter parameter setting and monitoring will become more convenient.
An AC variable frequency drive system consisting of one Mitsubishi PLC and no more than eight Mitsubishi inverters is a common small industrial automation system, which is widely used in small paper production lines, single-face corrugated board machinery, plastic film production lines, printing and dyeing and bleaching machinery, Various industrial fields such as loop type metal wire drawing machines. The simple control method can make the engineering scheme have many advantages of communication control, and can save many complicated calculations in RS-485 data communication, so that the engineering quality and work efficiency are greatly improved. However, this simple method also has its drawbacks: it can only control the frequency converter and cannot control other devices; in addition, the number of control inverters is also limited.
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