I am trying to control the speed of a three phase motor with an arduino. I have purchased the variable frequncy drive that connects the motor and can adjust the speed. However, I need way to read the speed and ultimately control the motor with the arduino. The arduino will also control other peripherals as well. Anyways, I know this is possible but am not sure how to do it. The variable frequency drive has an RJ12 port, and also digital inputs and relay outputs. My guess is you would have to connect something to the RJ12 port. But how does that connect to the arduino?
Which one did you buy? Does it have any datasheet or manual? Have you read the manual?
If it has Ethernet then you may need an Ethernet shield on your Arduino. I say "may" because it might be better to control it from your laptop over Ethernet without that Arduino.
Not all VFDs can be electronically controlled, some just use the knob on the front - did you check
whether your VFD was remotely controlable before buying?
I purchased the GS2 drive from automation direct. There are analog inputs and outputs on the drive, which I am wondering if it can be connected to the arduino. Theoretically it makes sense, the analog output of the drive will be an analog input to the arduino telling the arduino what speed the motor is running at. Similarly the analog input on the drive can be used to control speed from the arduino. I am just curious if this direct connection is possible.
There is also a RJ12 port on the drive, that uses MODBUS RTU protocol.
When asked which device you bought, its helpful to post the actual link to the data for the drive, rather
that force everyone to google around for it themselves.
Well I can only tell you want the manual says - you can use MODBUS to configure it, but you will need
to find more documentation. I couldn't figure out if the analog input is simply the pot on the front or
whether there's another 10V analog input for speed control. The 6 digital signals have factory default
behaviour useful for stop/start reverse.
I've used these drives before but never used an arduino to control one. My thought would be to setup the drive to use the analog input for speed and then find or build a circuit that would buffer and amplify the signal as the arduino PWM outputs at 5V and the drive analog input was designed to work with a 0 to 10V range.
Hope this helps.
I would love to know more about your application too.
I use an Uno to control frequency drives in an application. Used relays to switch the digital I/O on the VFD's and used digital potentiometers to control motor speed. The drives I used were GS1's and a GS2 from automation direct.
From the manual
Available via Mod bus.
Motor RPM h2107
Status location for the present estimated speed of the motor.
Modbus is serial and the documentation is thorough.
The RJ 12 connector is either rs232 or rs422 not ethernet