To control multiple inverters using arbitrary signals (4 to 20 mA) simultaneously, it is recommended to connect the signals (4 to 20 mA) in series. (This does not require other devices and connection is made simple.) However, this method allows for simultaneous control of the speed command only.

You can also input the signals (for example, 4 to 20 mA) to the programmable controller and then use the programmable controller to control the inverters.
This method has the following variations:
　1. Use the analog output from the D/A card of the programmable controller.
　2. Use the dedicated option (FR-A5NC) to connect the inverter and programmable controller and control the inverters via the network.
(The method 2. requires less control cables for the inverters and operation monitoring is easier.)

You can also control the inverters directly from the personal computer.
　A personal computer usually has a serial port. It conforms to the RS-232C standard in many cases. Convert it into RS422 (RS485) and connect it to the port PU of the FR-A500 to enable inverter control. (The port PU of the FR-A500 conforms to the RS485 communication specifications.)