To simulate the system without VFD: To simulate the system you will need two computers with different IP address. One to act as server for monitoring & other to act as pressure sender.

1. Hookup the Ethernet shield to the Arduino. Don't forget to short the INT jumper on bottom side of the official Arduino ethernet shield, as we are using interrupt based communication for ethernet stuff.
2. Connect Arduino to the USB port. Add ArduinoPID library in library folder of Arduino, compile & then upload the sketch provided here. Close Arduino IDE. Connect ethernet wire to the ethernet shield. It should get in the network. Try to ping 192.168.23.200...
3. Open MODBUS Simulator GUI & connect it to the serial port of the Arduino.
4. Open Pressure sender GUI in the same computer(This computer IP should be: 192.168.23.210).Run the GUI and Enter IP address as 192.168.23.200 & port as 1937. Press "Start Sending" button and it will start sending the pressure to 192.168.23.200 that is Arduino VFD controller.
5. Open VFD Controller GUI in another computer(This computer IP should be: 192.168.23.211). Change the IP addres in settings tab to 192.168.23.200 & Port to 1937. Restart the GUI. Now, you can see the frequncy of both motors.
6. Now if you close MODBUS Simulator GUI, the background of the VFD dials in the VFD Controller GUI will turn red indicating that the communication link is broken. If you again start the MODBUS Simulator GUI, the background color of the dials will turn green.

Testing the system with VFD:

1. Hookup the Ethernet shield to the Arduino. Don't forget to short the INT jumper on bottom side of the official Arduino ethernet shield, as we are using interrupt based communication.
2. Connect Arduino to the USB port. Add ArduinoPID library in library folder of Arduino, compile & then upload the sketch. Close Arduino IDE. Connect ethernet wire to the ethernet shield. It should get in the network. Try to ping 192.168.23.200...
3. For RS485 link,any RS485 shield can be used. Code uses standard hardware arduino serial pins (0 & 1) for communicating over RS485 with pin 8 as direction control of RS485 as it is half duplex system.
4. Power up VFD using 3phase supply & connect its RS485 output to the arduino RS485 output (A+ goes to A+ & B- goes to B-). (BE CAREFUL WITH THE THREE PHASE SUPPLY. CONNECT UNDER SUPERVSION OF EXPERIENCED ELECTRICIAN)
5. Also power up the pressure sender and have it in the network. (I have implemented pressure sender using another arduino+ ethernet shield + analog pressure sensor)
6. If everything is OK, it will start rotating the motor according to the pressure input.

Default IPs:

Arduino VFD Controller: 192.168.23.200...

Pressure Sender: 192.168.23.210...

Server IP(VFD Controller GUI): 192.168.23.211...

Default UDP Port: 1937...